And Nickel(Allyl)

Home , Hydroamination, Hydrosilylation

A Dissertation

entitled

Hydroamination and Hydrosilylation Catalyzed by Cationic Palladium- and Nickel(allyl)

Complexes Supported by 3-Iminophosphine Ligands

Hosein Tafazolian

Submitted to the Graduate Faculty as partial fulfillment of the requirements for the

Doctor of Philosophy Degree in

Chemistry

______Dr. Joseph A. R. Schmidt, Committee Chair

______Dr. Mark R. Mason, Committee Member

______Dr. Steven J. Sucheck, Committee Member

______Dr. John-David T. Smith, Committee Member

______Dr. Amanda Bryant-Friedrich, Dean College of Graduate Studies

The University of Toledo

December 2016

This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of

Hydroamination and Hydrosilylation Catalyzed by Cationic Palladium- and Nickel(allyl) Complexes Supported by 3-Iminophosphine Ligands

Hosein Tafazolian

Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Chemistry

The University of Toledo

December 2016

Chapter 1. A brief introduction to organometallic chemistry and catalysis is presented to explain the basics of the field to the reader. A few examples of catalysis, mainly hydroamination and hydrosilylation, and their mechanisms are presented. The significance of ligands in catalysis is also discussed.

Chapter 2. Six new 3-iminophosphine ligands and their cationic (allyl)palladium complexes were synthesized. These catalytically active palladium complexes were utilized in the hydroamination of cyclohexylallene with secondary amines in order to better understand the mechanism of this hydroamination reaction. The kinetics of the reaction were also studied with the help of time-resolved 1H NMR spectroscopy, as well as deuterium labeling experiments.

Chapter 3. Four new [(3-iminophosphine)nickel(allyl)]OTf complexes were synthesized and characterized by NMR spectroscopy, elemental analysis, and X-ray crystallography. Equimolar reactions of these new complexes with secondary amines provided useful information on the activation of these complexes in the presence of secondary amines. They also catalyzed the hydroamination of terminal allenes with iii secondary amines to produce allylamines in moderate to high yields, which were then characterized by 1H and 13C NMR spectroscopy and high resolution mass spectrometry.

Chapter 4. A previously synthesized [(3-iminophosphine)palladium(allyl)]OTf complex was found to be an efficient catalyst for the hydrosilylation of allenes with a wide range of hydrosilanes. Several new allyl- and vinylsilanes were synthesized catalytically and fully characterized. The observed regioselectivity and a double labeled

H/D experiment resolved the mechanism of the reaction while also explaining its regioselectivity.

Chapter 5. Various cationic palladium and nickel complexes were investigated in the hydrosilylation of imines, ketones, and alkynes. Several new allylamine, silylether and vinylsilane compounds were formed in this study and characterized. Substrate scope and mechanisms of the catalytic reactions are discussed.

Dedicated to

My Family and Friends

Table of Contents

Abstract ...... iii

Dedication ...... v

Table of Contents ...... vi

List of Tables ...... viii

List of Figures ...... ix

List of Schemes ...... x

1 Introduction to Organometallic Chemistry and Catalysis ...... 1

1.1 Organometallic Chemistry ...... 1

1.2 Catalysis ...... 3

1.3 Hydroamination and Hydrosilylation ...... 6

1.4 Significance of Ligands in Catalysis ...... 13

1.5 Hemilabile Ligands ...... 15

1.6 Conclusion ...... 17

2 The Electronic Role of 3-Iminophosphine Ligands in Palladium-Catalyzed

Intermolecular Hydroamination ...... 18

2.1 Introduction ...... 18

2.2 Results and Discussion ...... 21

2.3 Experimental Section ...... 34

2.4 Conclusion ...... 48 vi

3 Synthesis of [(3-Iminophosphine)nickel(allyl)]OTf Complexes and Their

Catalytic Activity for the Hydroamination of Allenes ...... 49

3.1 Introduction ...... 49

3.2 Results and Discussion ...... 51

3.3 Experimental Section ...... 62

3.4: Conclusion ...... 86

4 Efficient Regioselective Allene Hydrosilylation Catalyzed by a [(3-

Iminophosphine)Pd(allyl)]OTf Precatalyst ...... 87

4.1 Introduction ...... 87

4.2 Results and Discussion ...... 89

4.3 Experimental Section ...... 97

4.4 Conclusion ...... 107

5 Catalytic Hydrosilylation of Imines, Ketones, and Alkynes Utilizing Cationic 3-

Iminophosphine Complexes of Palladium and Nickel...... 109

5.1 Introduction ...... 109

5.2 Results and Discussion ...... 111

5.3 Experimental Section ...... 134

5.4 Conclusion ...... 166

References ...... 168

vii

List of Tables

1 Hammett constants and reaction yields of [(3IP)Pd(allyl)]OTf precatalysts ...... 23

2 Cationic [(3IP)Ni(allyl)]+ complexes ...... 52

3 Hydroamination of cyclohexylallene catalyzed by 4b ...... 56

4 Hydroamination of nhexyl-, nbutyl- and benzylallene catalyzed by 4b ...... 58

5 Hydroamination of 1,1-dimethylallene catalyzed by 4b...... 61

6 Optimization of catalytic hydroamination ...... 66

7 Crystallographic data for compound 4b ...... 85

8 Catalytic hydrosilylation of cyclohexylallene ...... 91

9 Catalytic hydrosilylation of dimethylallene ...... 93

10 Effect of reaction temperature ...... 112

11 Pd-catalyzed reduction of allylimines ...... 113

12 Investigation of ketimines ...... 118

13 Hydrosilylation of alkynes with silanes catalyzed by 15a ...... 121

14 Catalytic activity of 15a and 4a in the hydrosilylation ...... 128

15 Hydrosilylation of ketones with diphenylsilane catalyzed by 4a ...... 129

16 Substrate scope of alkyne hydrosilylation catalyzed by 4a ...... 133

17 Crystallographic data for compound 4a ...... 166

viii

List of Figures

1 Square planar Zeise’s salt ...... 1

2 Examples of well-known phosphine and carbene ligands ...... 15

3 Examples of hemilabile ligands ...... 16

4 General structure of 3-iminophosphine ligands ...... 17

5 Plot of ln(initial rate) versus ln([pyrrolidine]) ...... 26

6 Plot of ln(initial rate) versus ln([cyclohexylallene]) ...... 27

7 Rate of hydroamination reactions with catalysts 3a-f...... 28

8 Hammett plot of kobs in hydroamination reactions a, b, and c ...... 29

9 Kinetic isotope effects in the hydroamination of cyclohexylallene ...... 32

10 Crystal structure of 4b ...... 53

11 Time-resolved 1H NMR of reaction between 4b and thiomorpholine ...... 54

12 Products formed in crossover experiment...... 105

13 Proposed catalytic cycle for hydrosilylation of allylimines ...... 120

14 Palladium and nickel complexes (15a and 4a) for hydrosilylation study ...... 121

15 1H NMR spectrum for equimolar reaction of 15a and diphenylsilane ...... 126

16 Time-resolved 31P NMR from reaction of 15a and diphenylsilane ...... 126

17 Crystal structure of complex 4a ...... 127

List of Schemes

1 Ethylene polymerization catalyzed by a titanium catalyst ...... 2

2 Hydroformylation of propene ...... 5

3 Cross metathesis of an internal alkene and ethylene ...... 6

4 Suzuki coupling catalyzed by palladium ...... 6

5 Early transition metal-catalyzed intramolecular hydroamination ...... 8

6 Late transition metal-catalyzed intramolecular hydroamination ...... 8

7 Intermolecular hydroamination by late transition metals ...... 9

8 Intermolecular hydroamination of a conjugated diene ...... 10

9 Chalk-Harrod and modified Chalk-Harrod hydrosilylation mechanisms ...... 11

10 Glaser-Tilley hydrosilylation mechanism ...... 12

11 Hydrosilylation of a ketone catalyzed by a metal-tbutoxide complex ...... 13

12 Rhodium complex with a non-innocent cyclopentadienyl ligand...... 14

13 General synthetic route for [(3IP)Pd(allyl)]OTf complexes ...... 23

14 Catalytic hydroamination of cyclohexylallene ...... 25

15 Coordination of amine followed by intramolecular proton transfer ...... 30

16 Catalytic cycle proposed for palladium-catalyzed hydroamination ...... 33

17 Reaction of 4b with secondary amines ...... 55

18 Activation of the nickel precatalyst in the presence of amine ...... 62

19 Catalytic hydrosilylation of cyclohexylallene to form new allylsilanes ...... 90 x

20 Proposed catalytic cycles for hydrosilylation of allenes ...... 97

21 Palladium-catalyzed hydrosilylation/reduction of allylimines ...... 111

22 Hydrosilylation of 1,3-enynes with diphenylsilane catalyzed by 15a ...... 124

Chapter 1

Introduction to Organometallic Chemistry and Catalysis

1.1 Organometallic Chemistry

Organometallic compounds are a subset of coordination compounds, bearing a metal-carbon bond.1 Coordination compounds attracted a great deal of attention after the discovery of Werner complexes, and chemists have widely studied their unique properties and reactivity.1, 2 One can call the 19th century the time when coordination and organometallic chemistry began, although many organometallic compounds synthesized earlier were correctly characterized later on.1, 2 A good example is Zeise’s salt, discovered in 1827 and assumed to be KCl·PtCl2·EtOH, but with a correct formula that

2 was established later as K[PtCl3(C2H4)] (Figure 1).

Figure 1. Square planar Zeise’s salt.

Experts divide organometallic chemistry into the subfields of main group and organotransition metal chemistry.3 For instance, alkyllithium compounds, Grignard reagents, and alkylaluminum complexes fall into the first category, while d- and f-block elements (groups 3-12) bearing metal-carbon fragments merge into the latter. d-Block elements, due to their vast applications in catalysis, have garnered a great deal of attention. To be precise, they consist of early transition metals and late transition metals.

Early transition metals are on the left side of the transition series and have been utilized in catalysis such as polymerization (Scheme 1).4 Late transition elements are on the right side of the transition series and have also shown catalytic applications in many processes, including hydroformylation, (de)hydrogenation, oligomerization, and many other catalytic reactions.1, 2, 5

Scheme 1. Ethylene polymerization catalyzed by a titanium catalyst.

Considering the history of organometallic chemistry, one can say that the 20th century was the golden age of organometallics given all the discoveries made in this era.

In the early 20th century, Sabatier established the catalytic hydrogenation of olefins using nickel, leading to the Nobel Prize in 1912, shared with Grignard for his work on the reaction of magnesium with organohalides.1 Many processes were discovered before or around the mid 20th century, such as Fischer-Tropsch chemistry, developed in Germany during WWII, catalytic cracking of crude oil by acidic clays and later on by zeolites, and cobalt-catalyzed hydroformylation (Roelen’s chemistry).1 Although early catalytic

cracking of crude oil utilized aluminum in the catalyst, further refinements utilized transition metals to increase gasoline yield.3, 5 Despite the benefits gained from early organometallic chemistry in industry, organometallics was not well studied until the

1960’s when rhodium-catalyzed hydroformylation, olefin metathesis, and Ziegler-Natta processes came under scrutiny.6-14 Study of active intermediates in hydroformylation led to highly efficient catalytic conditions and selectivity.7 The discovery of metallocenes coupled with the emergence of Ziegler-Natta polymerization led to the development of well-defined polymerization systems.14 Additionally, the amazing chemistry of metal- carbon multiple bonds was introduced by Fischer, and further investigations led to greater selectivity of these systems for olefin metathesis, especially with the understanding that the mechanism of these reactions employs a metallocyclobutane intermediate.15, 16 Also noteworthy, in the same era many other reactions became possible via the help of organotransition metal catalysis, such as the formation of acetic acid from methanol and carbon monoxide in the presence of rhodium-carbonyl complexes.1, 2 Following these great discoveries, the late 1970’s yielded the cross-coupling reactions known as Stille and

Suzuki coupling reactions, which led to new carbon-carbon bonds.17, 18 Exploration of cross-coupling reactions and olefin metathesis continues to date and ultimately led to two

Nobel Prizes.

1.2 Catalysis

Catalysis is a major application of organometallic compounds; however, many reactions also take advantage of stoichiometric amounts of organometallic reagents to deliver an organic fragment.2, 19 A catalyst is a substance used in less than stoichiometric 3

amount that increases the rate of a reaction by decreasing the activation energy without being consumed.1-3, 5 Using a catalyst not only improves the rate of a reaction, but also often induces selectivity (chemo-, regio-, and stereoselectivity). Traditionally, catalysts are classified as heterogeneous or homogeneous. Heterogeneous catalysts are often ones in which the catalysis occurs on the surface of a solid, but more generally, do not perform in the same phase as the reactants. Homogeneous catalysts are the exact opposite, as they exist in the same phase as reactants.20 Beyond the significance of both types in a variety of processes, there are certain advantages and disadvantages for each. Heterogeneous catalysts are highly favored by petroleum and other large industries due to the low cost of the catalyst, its ease of recovery, and its reactivation. On the other hand, when selectivity matters most, homogeneous catalysts are often more desired. In general, the latter type is molecular and single site, making it easier to characterize and study the catalyst performance while also making the detection of intermediates more facile.1, 20 These studies can be done with simple solution techniques such as NMR experiments. However, advances in different characterization and spectroscopic techniques including solid state

NMR spectroscopy and electron microscopy in the past few decades have allowed chemists to investigate the mechanism of heterogeneous catalysis. One of the biggest drawbacks of homogeneous catalysis is the separation of the catalyst from the product at the end of the process, adding to the cost. Catalytic cracking of crude oil to increase the gasoline range molecules, the greatest catalytic process utilizing zeolites (porous, crystalline aluminosilicate materials), is a heterogeneous catalytic process.20 Rhodium- catalyzed hydroformylation is the biggest homogeneous catalyzed industrial process.1, 3

The ease of mechanistic investigations for hydroformylation (a homogeneous system) has 4

enabled this chemistry to achieve very high selectivity, and many examples of regio- and enantioselective hydroformylations have been reported (Scheme 2).7

Scheme 2. Hydroformylation of propene.

Other examples of homogeneous catalytic reactions are numerous, both in the chemical industry and in research laboratories worldwide, utilized in a great breadth of organic transformations. Homogeneous catalysts can be further divided into organocatalysts and metal-based catalysts. Metal-based systems include main group, early, and late transition metal catalysts. The first class often lacks functional group tolerance, which reduces its industrial application.21-23 Although early transition metals have a higher level of tolerance to organic functionalities, they commonly suffer from being highly oxygen and moisture sensitive. On the other hand, the lower sensitivity of late transition metals toward oxygen and moisture, as well as tolerance to the presence of organic functionalities, has led to a great deal of investigation of their chemistry and catalytic activity.1 Catalysis is also one of the twelve green chemistry principles

(lowering cost by applying less energy).1, 24 A short list of some known reactions catalyzed by late transition metals in homogeneous systems consists of hydroformylation,7, 25-31 olefin metathesis (Scheme 3),32-38 (de)hydrogenation,39-44 olefin oligomerization,45-48 C-C cross coupling (Scheme 4),49-55 aryl amination,56, 57 hydroamination,58-63 and hydrosilylation.64, 65

Scheme 3. Cross metathesis of an internal alkene and ethylene (also known as ethenolysis).

Scheme 4. Suzuki coupling catalyzed by palladium.

Many reactions catalyzed by organometallic complexes are unique because of the formation of specific new bonds or the novelty of products formed, but a large number of these examples have low atom economy and produce significant waste that contradicts with the green chemistry criteria. Thus, atom economy has become very important in designing new catalytic reactions. Reactions such as hydroformylation,7, 25 hydroamination,59, 60 hydrosilylation,64 hydroarylation,66-68 olefin isomerization,69-73 and reductive coupling74-76 are 100% atom economic reactions and highly favored if performed selectively since no waste or byproduct is produced.

1.3 Hydroamination and Hydrosilylation

Hydroamination, defined as the direct addition of N-H to a C-C multiple bond, is an interesting C-N bond forming reaction that cannot be obtained without a catalyst except with highly activated reactants.59, 60 Numerous organic and catalytic reactions can lead to the formation of new nitrogen-carbon bonds, but low atom economy and harsh reaction conditions have urged organometallic chemists to study catalytic routes to obtain

these molecules.77-92 A high reaction barrier is the main reason a catalyst is required for hydroamination.60 Nearly all hydroamination examples require a catalyst, except in rare cases where the unsaturated substrate is highly activated through conjugation where either no catalyst is necessary or the metals work as general Lewis acids to catalyze the reaction.93-98 Many research groups have focused on the catalytic hydroamination of unsaturated systems and investigated the mechanism of this process.59, 60, 99-118 However, finding a general catalyst for hydroamination of olefins remains a significant challenge.

Hydroamination can be classified as intra- or intermolecular. In intramolecular hydroamination, the N-H is tethered to the C-C multiple bond and is usually entropically favored compared to the intermolecular version.59, 60 Various mechanisms for intramolecular hydroamination have been proposed, among which two are generally accepted (Schemes 5 and 6).59, 119 In the first one, proposed for early transition metal catalysts, metal-amido complexes serve as the active catalyst, and insertion of the multiple bond into the metal-amido intermediate in a concerted mechanism generates the metal-carbon bond. Protonation by the amine substrate in the next step forms the product and regenerates the active catalyst.120, 121 A different mechanism has been suggested for intramolecular hydroamination by late transition metals. Nucleophilic attack on a coordinated olefin results in a zwitterionic ammonium species and intramolecular protonation of the metal-carbon bond gives the hydroamination product and restores the active catalyst.59, 60, 119, 122, 123

Scheme 5. Early transition metal-catalyzed intramolecular hydroamination.

Scheme 6. Late transition metal-catalyzed intramolecular hydroamination.

In intermolecular hydroamination catalyzed by metals, the operable mechanism is highly dependent on the catalyst used. Two of the mechanisms are very similar to those proposed for intramolecular hydroamination, invoking either insertion of an olefin into a metal-amido bond or nucleophilic attack of an amine onto the coordinated olefin, each of

which is followed by protonation of the metal-carbon bond (Scheme 7).59, 60, 124-128

Another mechanism, mostly invoked in the intermolecular hydroamination of 1,2- or 1,3- dienes by late transition metals, proceeds through insertion of the diene into an active metal-hydride catalyst to form an allylic intermediate. The next step is very similar to the allylic amination mechanism, in which the amine nucleophile attacks the coordinated allyl unit and creates an allylammonium species. Proton transfer from the ammonium to the electron-rich metal by oxidative ligation coupled with dissociation of the weakly- bonded olefin regenerates the active catalyst and yields the hydroamination product

(Scheme 8).60, 129, 130

Scheme 7. Intermolecular hydroamination by late transition metals via a zwitterionic intermediate.

Scheme 8. Intermolecular hydroamination of a conjugated diene by late transition metals via an allylic intermediate.

Hydrosilylation, the direct addition of a silicon hydride to an unsaturated reagent, is another 100% atom economic reaction that has been utilized for a broad range of purposes in synthetic chemistry.131, 132 Unsaturated compounds for this reaction can be C-

C double or triple bonds or a C-X (X=heteroatom) multiple bond. Hydrosilylation of an olefin is a useful route to produce new organosilicon compounds that are subsequently useful as synthetic intermediates for Hiyama cross coupling reactions.131 Initially proposed by Chalk and Harrod, the oxidative addition of an Si-H bond to an electron-rich metal, followed by coordination and then insertion of an olefin into the M-H bond and finally, reductive elimination accounted for the olefin hydrosilylation activity of transition metals. Other studies showed that hydrosilylation can be obtained analogously to the Chalk-Harrod mechanism, but instead of insertion of the olefin into the M-H bond, it occurs at the M-Si bond, referred to as silylmetalation. This alternate mechanism was then dubbed the modified Chalk-Harrod mechanism (Scheme 9).131, 133 10

Scheme 9. Chalk-Harrod and modified Chalk-Harrod hydrosilylation mechanisms.

With recent progress in the design of organotransition metal catalysts for the hydrosilylation of olefins, many alternate mechanisms have been suggested. Among these, the Glaser-Tilley mechanism is quite notable.134 Specifically, this mechanism suggests that phenylsilane gets activated by a ruthenium catalyst to form a silylene complex. Then, Si-H is directly added to the olefin. This is further followed by H- migration to the silylene and reductive elimination to generate the alkylsilane product and the active catalyst (Scheme 10).131, 134, 135

Scheme 10. Glaser-Tilley hydrosilylation mechanism.

In addition to the hydrosilylation of olefins, the catalytic hydrosilylation of other unsaturated systems with carbonyl, imine, and nitrile functionality has been growing rapidly. Many regio- and enantioselective examples of catalytic hydrosilylation of carbon-heteroatom unsaturated bonds have been reported as a means to their selective reduction.131, 136-160 In these cases, catalytic hydrosilylation reduces the carbon- heteroatom bond by producing heteroatom-silyl compounds (silylamine or silylether).

The newly formed heteroatom-silyl bond is often hydrolyzed under mild conditions

(acidic, basic, aqueous or over silica gel) to yield the related alcohol or amine from the corresponding carbonyl or imine functionality.131 In addition to the tunable selectivity of this method, one advantage it has over traditional methods for ketone and imine 12

hydrogenation with metal hydrides is a higher level of safety, avoiding the production of hydrogen gas evolved when quenching metal hydrides. This silylation method is comparable to catalytic hydrogenation of carbonyls and imines and to some extent more effective than hydrogenation.131, 136, 161, 162 The mechanism of catalytic hydrosilylation of carbonyls and imines is thought to take place by π-coordination of a carbon-heteroatom multiple bond to a metal center with subsequent 1,2-insertion into the metal-hydride bond produced by interaction of the metal and hydrosilane. Then, via a concerted mechanism hydrosilane regenerates the active catalyst and liberates the product (Scheme 11).131, 163,

164

Scheme 11. Hydrosilylation of a ketone catalyzed by a metal-tbutoxide complex.

1.4 Significance of Ligands in Catalysis

In coordination chemistry, ligands are classified in a variety of ways, such as weak field or strong field, neutral or ionic, σ- or π-donor or acceptor, and monodentate or

multidentate ligands.2, 5, 165 In metal-based catalysis, they can be further categorized as spectator or actor ligands.2 Spectator ligands are those that function to support the precatalyst, and as the catalyst gets activated, they either leave the metal center during catalyst activation by the substrate or remain on the metal throughout catalysis as an ancillary ligand, providing the electronic and steric features required for the process.

Ligands also provide solubility for the catalyst, a necessity in homogeneous catalysis. On the other hand, actor ligands participate in the reactivity during catalysis. This can occur either by undergoing a chemical reaction or reversible dissociation and coordination to the metal center. Quite often, actor ligands serve as a proton shuttle or mediate redox reactivity.115, 166-169 Organometallic chemists often refer to actor ligands as non-innocent ligands, and many ligands that initially seem to be unreactive in catalysis are often found to be actor ligands. For instance, reports of the non-innocent roles of allyl and cyclopentadienyl ligands have been published recently (Scheme 12).170, 171 Normally, ligands utilized in many of the named reactions are ancillary and only provide electronic and steric features. Phosphines (mono- and bidentate) and carbenes are commonly of this type (Figure 2). Although they act solely as a support for the metal center, they can be tethered to another donor atom or functional group to present actor properties.

Scheme 12. Rhodium complex with a non-innocent cyclopentadienyl ligand.

Figure 2. Examples of well-known phosphine and carbene ligands.

1.5 Hemilabile Ligands

Hemilabile ligands consist of multiple donor atoms wherein these donor atoms display different electronic properties. The term hemilabile was first introduced by

Jeffrey and Rauchfuss, referring to an o-(diphenylphosphino)anisole ligand.172 The majority of hemilabile ligands are P and N or P and O donors and in general, at least one soft and one hard donor exist within the structure of the ligand (Figure 3).173-177 The broad tunability of these multidentate ligands have resulted in their vast application.

Historically, most are bidentate neutral donor ligands, although anionic and pincer types have also been reported.165, 178, 179

Figure 3. Examples of hemilabile ligands.

Due to the windshield wiper effect and reversible coordination to a metal center

(as potential actor ligands), hemilabile ligands have found many applications in metal- based catalysis.165, 179 Another advantage is the facile chirality installation on the ligand, as significantly studied for PHOX (phosphinooxazoline) ligands.165, 174, 180, 181 Over the past decade, our group has synthesized and studied the coordination behavior of one particular class of hemilabile ligands, known as 3-iminophosphines (Figure 4). Many palladium complexes of the 3-iminophosphine (3IP) ligand have been synthesized in our group and their catalytic activity in the hydroamination of olefins and aryl amination has been studied.114, 116-118, 182, 183 The significance of this ligand class is due to their ease of synthesis and their tunable electronic and steric properties. Our group has modified the different units of 3IP, including installing various alkyl and aryl groups on the phosphorus and imine units, as well as changing the backbone ring size.

Figure 4. General structure of 3-iminophosphine ligand (R, R’ = aryl or alkyl, n = 1-5) and some of its previously synthesized palladium complexes.

1.6 Conclusion

In summary, the synthesis of organometallic compounds and investigation of their reactivity have resulted in many outstanding discoveries in the field of catalysis, achieving many reactions that are not obtainable without a catalyst. Mechanistic studies on many catalytic reactions have proven the crucial role of ligands throughout catalytic processes, and in some cases, small modifications of the ligand have significantly increased the catalytic activity. Since the primary interest in our research group is the application of our synthesized transition metal complexes supported by 3IP ligands to catalysis, it is important to understand the role of these ligands and the reactivity of their metal complexes in the presence of organic and inorganic reagents. For instance, our previous study on the reactivity of (3IP)PdCl2 complexes in the presence of amines showed the hemilability of the 3IP ligand, which led us to utilize its palladium complexes in the catalytic hydroamination of alkynes and allenes. In this dissertation, many catalytic reactions have been studied using nickel and palladium complexes of 3-iminophosphine ligands and efforts have been undertaken to elucidate the role of the ligand, as well as that of catalyst activation to elucidate the relevant catalytic reaction mechanism and expand the substrate scope of these reactions.

Chapter 2

The Electronic Role of 3-Iminophosphine Ligands in Palladium-Catalyzed Intermolecular Hydroamination

2.1 Introduction

In addition to being 100% atom economic, hydroamination is a particularly versatile method for the production of new C-N bonds in N-containing organic frameworks. By utilizing a broad diversity of unsaturated substrates, a wide range of target compounds including amines, enamines, and imines can be obtained.184 Over the past two decades, many structurally-modified transition metal catalysts have proven to be capable of regio- and enantioselective intra- and intermolecular hydroamination of C-C unsaturated bonds.59, 60, 99, 101-103, 124, 185 Intramolecular hydroamination can be utilized in the synthesis of N-heterocycles, facilitating multi-step reactions for production of biologically active molecules in fewer steps, whereas intermolecular hydroamination provides acyclic amines that serve as common building blocks for pharmaceuticals and organic syntheses.60, 186-188 Intermolecular hydroamination is much more challenging than intramolecular hydroamination as the process is calculated to be only slightly exothermic for many substrates, and it also suffers from an unfavorable entropic term.60As a result, 18

efforts to develop useful intermolecular hydroamination catalysts have recently been a topic of great interest worldwide.60, 61, 99, 104, 108, 189-194 Furthermore, the broad significance of catalytic hydroamination as a tool in both organic and organometallic synthesis has made mechanistic studies for better understanding of the catalytic cycles in these processes a critical pursuit towards enabling organometallic chemists to rationally tune catalyst frameworks and consequently achieve higher catalytic activities and reaction yields.105, 122, 195-201

The most significant impact of catalytic hydroamination can be seen through the reduced cost in making valuable products such as allylamines which serve as convenient organic intermediates in the synthesis of complex molecules.84, 202 Even simple achiral allylamines have attracted a great deal of attention recently with many efforts undertaken to refine the synthetic methods for this class of compounds.203, 204 Allylamines, in spite of being well-known, are not easy to synthesize with many reported synthetic routes reported requiring either multiple steps and tedious workups or stoichiometric amounts of organometallic reagents.84, 202 Beyond their applications in traditional organic synthesis, allylamines can be used as substrates for alkene metathesis reactions adding to their usefulness and versatility.9 Conjugated dienes and allenes are two general substrate classes that can serve as precursors to allylamines via catalytic hydroamination.59, 60

Hydroamination of conjugated dienes has been widely investigated and numerous regioselective and enantioselective transition metal catalysts have been developed.59, 60,

129, 130, 205 In contrast, examples of intermolecular hydroamination of allenes, originally reported in 1992,125 are less common and few catalysts with high functional group tolerance for unactivated allenes have been reported.59, 60, 99, 104, 189 Moreover, due to the 19

limited number of allene hydroamination reports, few comprehensive mechanistic studies have been undertaken to date.108, 195, 206

Over the past few years, our group has focused on the hydroamination of mono- substituted allenes with primary and secondary amines catalyzed by allylpalladium complexes supported by 3-iminophosphine (3IP) ligands.114, 116-118 Recently, we reported the most active catalyst known for the intermolecular hydroamination of mono- substituted allenes with anilines, which also displayed a high functional group tolerance.117 This catalyst operated efficiently at ambient temperature and provided moderate to high yields of hydroamination products.117 The hydroamination of allenes has also been pursued by the Breit group in Germany quite successfully,108 although their catalyst requires the more expensive rhodium metal center and uses high temperature in the catalytic process in contrast to our systems that function at ambient temperature.

In parallel to the current study, we recently reported the correlation of backbone ring size and phosphorus substituent on catalytic activity with these allylpalladium 3- iminophosphine complexes.114 This parallel study helped elucidate the catalytic effect of

σ donation from the phosphorus and ring strain due to backbone composition.

Summarizing these results, tert-butyl groups on the phosphine resulted in higher yields for hydroamination than phenyl groups. We deduced that the stronger electron donation of the tert-butyl groups makes the trans allylic carbon more labile and additionally, the tert-butyl group carries more steric bulk, potentially impacting various steps in the catalytic cycle. Most importantly, the increased steric bulk of the tert-butyl group could assist catalysis by increasing the rate of reductive elimination of the product allylamine.

In other tests, we found that a smaller backbone ring size was most suitable for the 20

catalysis, which we attributed to increased ring strain and decreased bite angle, both of which promote displacement of the imine from palladium to allow for coordination of reagent amine. In these prior studies, only tert-butyl and xylyl groups on the imine unit were tested. Given the limited set of substituents, we were unable to make any significant conclusions regarding the steric and electronic effects of the 3IP imine group, and its correlation to hydroamination catalytic activity remained ambiguous. Thus, we set out to determine the effect of electron-withdrawing and electron-donating imine substituents on the catalytic hydroamination, as described in this chapter. Additionally, related deuterium kinetic isotope effect experiments are performed. Finally, based on the results herein and our other recent report,114 we propose a rational catalytic cycle for the hydroamination of mono-substituted allenes with primary and secondary amines, as related to 3- iminophosphine supported palladium catalysts.

2.2 Results and discussion

It is important to understand the catalytic mechanism in order to improve the activity of 3IP-Pd catalysts. Thus, we set out to investigate the effect of imine electronics on catalyst activity. For this purpose, a set of new 3IP ligands (2a-f) was designed, where the groups on phosphorus (phenyl) and the alicyclic backbone (cyclopentene) were kept constant (Scheme 13). The only variable for these new ligands involved the electronics of the imine unit, controlled by different substituents (EDG or EWG) at the para position of a phenyl group attached to the nitrogen (Table 1). By varying the para substituents in these new catalysts, we were poised to correlate our experimental data with Hammett constants,207 as these empirically derived constants adequately represent the electron- 21

donating and electron-withdrawing character of substituents in reactions involving substituted benzene derivatives. In this fashion, it was feasible to investigate the effect of imine electronics on catalytic hydroamination with sterics held constant.

The ligands (2a-f) and related catalysts (3a-f) were synthesized using protocols related to those developed previously in our group:114 first, reaction of the Vilsmeier-

Haack reagent with cyclopentanone, then Schiff base condensation with a para- substituted aniline, and finally treatment with lithium diphenylphosphide to produce each

3IP ligand (2a-f). During the synthesis of these new 3IP ligands, we observed very poor stability of the newly synthesized β-chloroimines (1a-f). Reaction progress in the synthesis of 1a-f was monitored by 1H NMR to result in excellent product formation.

Unfortunately, after the reaction workup (involving passage through a short column of silica gel followed by quick drying over MgSO4), as the solvent was removed, compounds 1a-f started to decompose in less than one hour, even though they were relatively pure at this point. We also performed the reaction and workup under nitrogen atmosphere, but it did not resolve these decomposition problems. This instability of 1a-f forced us to characterize them only by NMR spectroscopy and then use them immediately. Thus, 1a-f were quickly isolated under a nitrogen atmosphere and treated with lithium diphenylphosphide directly to transform them to ligands 2a-f. After successful isolation, these ligands were coordinated to commercially available allylpalladium chloride dimer, and a subsequent salt metathesis with silver triflate yielded the precatalysts (3a-f).

Scheme 13. General synthetic route for [(3IP)Pd(allyl)]OTf complexes.a

a o o i) 2 eq. of DMF, 1.2 eq. of POCl3, 0 C then stirred at RT for 14 h; 0 C, NaHCO3; ii) o o diethyl ether, 4Å molecular sieves, 0 C; iii) 1.4 eq. LiPPh2, diethyl ether, 0 C then warmed to RT.

Table 1. Hammett constants and reaction yields of [(3IP)Pd(allyl)]OTf precatalysts.

Y Hammett constant Chloroimine Ligand (% yield) Precatalyst

(para substituent) (σp) (unisolated) (two steps) (% yield)

Dimethylamino -0.830 1a 2a (74) 3a (59)

Methyl -0.170 1b 2b (69) 3b (62)

Ethyl -0.150 1c 2c (65) 3c (54)

Isopropyl -0.150 1d 2d (63) 3d (52)

Hydrogen 0.000 1e 2e (71) 3e (60)

Chloro 0.227 1f 2f (76) 3f (69)

Several years ago, our group investigated the hemilability of 3IP ligands in non-

208 catalytically active (3IP)PdCl2 complexes. These compounds displayed extremely weak coordination by the imine unit of 3IP and a strong affinity toward coordination of amines in place of the chelating imine. We have since come to believe that this hemilability plays a significant role in hydroamination catalysis and that coordination of the amine substrate to 3IP palladium complexes is crucial for catalytic hydroamination.

Thus, systematic manipulation of the basicity of this imine unit should have a marked effect on catalytic activity. Bearing this in mind, we set out to investigate a series of catalytic experiments using our new complexes (3a-f). Given our studies from the past several years,114, 116-118 we decided to investigate the hydroamination of cyclohexylallene with several amines (pyrrolidine, piperidine, morpholine, and 1,2,3,4- tetrahydroisoquinoline; Scheme 14). This group of substrates was chosen because we expected slow to moderate catalytic rates, allowing for more accurate comparison of the effects of the different imines in these catalysts. That is, if more rapid substrates were chosen, conversion data would have to be collected immediately, with greater experimental error as a result. Since we have previously developed very effective catalysts for hydroamination of cyclohexylallene with these amines,118 our goal in the present work was to understand the effect of imine electronics at the expense of overall reaction rate.

Scheme 14. Catalytic hydroamination of cyclohexylallene.a

a Catalytic procedure: Reactions were carried out at 25 oC in NMR tubes prepared in a glovebox using benzene-d6 as the solvent (800 µl), catalyst (0.025 mmol), secondary amine (0.50 mmol), and cyclohexylallene (0.50 mmol), with C6H6 (0.50 mmol) as an internal standard. Conversion was monitored by 1H NMR spectroscopy; b Isolated yields were obtained from the average of six hydroamination reactions catalyzed by 3a-f for each amine.

Our early experiments revealed that variation of the imine electronics had a drastic effect on the catalytic activity in these 3IP complexes. Because of our past hemilability experiments, we initially expected catalysts with less electron-donating substituents at the para position of the imine to show higher activity in hydroamination, since the resulting imine coordination to palladium would be weaker, facilitating displacement by substrate amine and entry into the catalytic cycle. In contrast, it was observed that upon proceeding from negative values of the Hammett constant (more electron-donating) to positive ones (more electron-withdrawing), there is a significant increase in reaction rate, which reaches a maximum and then subsequently decreases for the most electron-poor imines. To fully understand the observed trend and kinetics of these reactions, detailed 1H NMR studies were undertaken.

Reaction order of secondary amine: Since our initial experiments revealed 3c as the most active hydroamination precatalyst, 3c was utilized in catalytic reaction a to determine the reaction order in amine. In order to accomplish this, pyrrolidine was added to a mixture of benzene (0.50 mmol), C6D6 (800 µl) and 3c (0.025 mmol), followed by addition of cyclohexylallene (0.50 mmol). 1H NMR spectra were recorded every 2 minutes with the temperature preset to 25 oC. Quantities of 0.25, 0.50 and 1.0 mmol of amine were tested in duplicate runs and ln[initial rate] was plotted versus ln([pyrrolidine]). The near unity slope of this line indicates that the reaction is first order in amine within experimental error (Figure 5).

Figure 5. Plot of ln(initial rate) versus ln([pyrrolidine]).

Reaction order of allene: In continued efforts to probe the hydroamination mechanism, we set out to verify that allene insertion was not involved in the rate determining step by comparing the reaction rates of pyrrolidine with 0.5, 1, and 2 eq. of cyclohexylallene. Similar to the experiments above, catalytic reactions were investigated by 1H NMR spectroscopy. Pyrrolidine (0.50 mmol) was added to a mixture of benzene

(0.50 mmol), C6D6 (800 µl) and 3c (0.025 mmol), followed by addition of 0.25, 0.50 and

1.0 mmol cyclohexylallene in separate experiments. 1H NMR data was collected every 26

two minutes with temperature preset to 25 oC. The ln[initial rate] values were plotted versus ln[cyclohexylallene] giving a slope of 0.0760, suggesting that the catalytic reaction is zero order in allene (Figure 6). The absence of allene from the rate law is not surprising as many previous studies have demonstrated rapid insertion of olefins into Pd-

C and Pd-H bonds with a variety of ligand sets.209-211

Figure 6. Plot of ln(initial rate) versus ln([cyclohexylallene]).

Y = NMe Y= Me 2

E t

Y = Et Y = iPr

Figure 7. Rate of hydroaminationY reactions with catalysts 3a-f for pyrrolidineY = Cl as a Y = H =

representative amine.

Figure 8. Rate of hydroamination reactions with catalysts 3a-f for pyrrolidine as a representative amine.

Correlation between observed reaction rates and Hammett value: With an understanding of the reaction order of the catalytic substrates, specifically rate = kobs[amine], we knew that the secondary amine was involved in the rate determining step.

A possible mechanism involving coordination of the amine requires concomitant dissociation of the ligand’s imine unit and thus, the electronics of the imine unit were investigated. In order to achieve this, we determined the observed first order rate constants (kobs) for all six catalysts with three of the secondary amines. These were then plotted versus the Hammett σρ values for the imine fragment of each ligand (Figure 8, also see Figure 7 for the representative rate constant determinations).

Figure 9. Hammett plot of kobs in hydroamination reactions a, b, and c.

As had been the case with our initial test reactions, upon proceeding from electron-donating to electron-withdrawing substituents, reaction rates increase to a maximum in each case and then subsequently decrease (Figure 8). Though initially unexpected since imines with the largest σp values would be most amenable to substitution by the substrate amine (EWG would facilitate imine displacement by the amine), this peak in catalytic activity versus Hammett constant implied that there may be

two steps in the mechanism with similar rate constants, with one or the other dominant depending on imine electronics. We hypothesized that the two relevant steps in the catalytic cycle involved coordination of reagent amine to the Pd catalyst, followed by intramolecular deprotonation of the coordinated amine by the dissociated imine unit of

3IP (Scheme 15). The reduced reaction rates for the electron-rich imines represent a rate determining step involving displacement of this coordinated imine by the reactant amine, while the slower reaction rates for the electron-poor imines are consistent with proton transfer becoming kinetically limiting. This latter intramolecular proton transfer step would be expected to be highly dependent on the basicity of the imine fragment of 3IP.

Ultimately, this proton transfer step provides a palladium intermediate bearing an amido ligand that can readily undergo reductive elimination in a rapid step, as elegantly demonstrated by Hartwig and coworkers previously.212-215

Scheme 15. Coordination of amine followed by intramolecular proton transfer.

In summary, this mechanism involving two consecutive steps with similarly slow kinetics but opposite correlation with imine electronic character explains why 3e and 3f, which are carrying the least electron-donating substituents on the imine unit, do not provide the most active catalysts. Although they almost definitely undergo coordination of the amine, their catalysis is hindered by poor reactivity in the intramolecular

deprotonation step, resulting in poor reaction rates. We also investigated two catalysts with different substituents but the same Hammett constant to compare their catalytic activity. Ethyl (3c) and isopropyl (3d) substituents have identical Hammett constants

(σp). Since the steric bulk of the para substituent should have little or no impact on catalysis, the same reaction rate for both was expected (Figure 8). In general, these two catalysts showed very similar catalytic activity for each substrate, although 3d gave slightly slower rates in each case, which we attribute to a more pronounced albeit slow catalyst decomposition observed with 3d.

Following the Hammett study, a deuterium labelled amine was used to explore the kinetic isotope effect on the catalysis, as shown in Figure 9. It was previously shown that kH/kD for hydroamination of ethylene with aniline catalyzed by an active Ru complex at

80 oC was 2.2±0.1.216 This number was consistent with earlier studies and was related to

N-H(D) bond activation, since this step was considered to be the rate determining step.

For catalyst 3c, kH/kD for the reaction shown in Figure 9 was found to be approximately

5.2. To determine this value, the ratio of the slopes of ln([piperidine]) versus time was utilized (Figure 9). The large primary kinetic isotope effect observed strongly implies that cleavage of the N-H bond is involved in the rate determining step of the catalysis, consistent with the intramolecular proton transfer step involved in the discussion of

Hammett correlation above.

Figure 10. Kinetic isotope effects in the hydroamination of cyclohexylallene with piperidine.

In addition to kinetic rate data, our study on hydroamination using deuterated piperidine revealed that the deuterium becomes attached to the central carbon of allene exclusively. Previous reports involving a Rh(I/III) catalytic system showed that formation of a vinylic species followed by β-hydride elimination can shift the labeled proton to the terminal carbon of mono-substituted allenes, but we see no evidence of such reactivity using our Pd system.108

Scheme 16. Proposed catalytic cycle.

On the basis of our previous studies regarding hemilability of (3IP)PdCl2 upon treatment with a wide range of amines208 and the results discussed above, we propose a new catalytic cycle for hydroamination of allenes with secondary amines using

[(3IP)Pd(allyl)]OTf as the precatalyst (Scheme 16). In this catalytic cycle, the palladium precatalyst, after reaction with the substrate amine, produces a highly reactive and coordinatively unsaturated Pd(II) hydride species. Next, allene rapidly inserts into the Pd-

H bond to form a π-allylpalladium complex. Subsequently, hemilability of 3IP plays a role as substrate amine coordinates to the palladium(II) with displacement of the 3IP imine unit. In the final steps, proton transfer from the coordinated secondary amine to the imine unit of the 3IP provides an amido complex of Pd(II) which then undergoes reductive elimination and protonation of palladium to complete the catalytic cycle.

Alternatively, it is also possible that in the last step, after coordination of amine to 33

palladium, an internal attack of the coordinated amine on the allyl group, followed by reductive elimination, forms the product. The results produced herein are incapable of resolving these two mechanisms. Notwithstanding, the 1H NMR studies during active catalysis unequivocally demonstrate monodentate coordination of the 3IP ligand to the metal center in the catalyst resting state, as evidenced by the appearance of a 1H resonance at low field (9.62−9.83 ppm) assigned to the HC=N proton of the decoordinated imine moiety. Thus, we assert that the proton transfer step from amine to imine is often rate limiting, especially in cases involving the most active 3IP-palladium complexes, although a rate-limiting internal attack on the allyl group is also consistent with the experimental data for this system.

2.3 Experimental Section

General Methods and Instrumentation: 2-Chlorocyclopent-1- enecarbaldehyde,114 lithium diphenylphosphide,217 3-iminophosphine ligands 2a-f, and

[(3IP)Pd(allyl)]OTf complexes 3a-f were prepared via previously published methodology.182 β-Chloroimines 1a-f were synthesized under ambient conditions. All further manipulations were performed under a nitrogen atmosphere using either Schlenk techniques or a nitrogen-filled glovebox, unless otherwise noted. Solvents were dried prior to use; methylene chloride was passed through two columns of 4Å molecular sieves and degassed with high purity nitrogen (99.995%). Pentane, diethyl ether and toluene were passed through columns of activated alumina and 4Å molecular sieves and degassed with nitrogen. CDCl3 and C6D6 were purchased from Cambridge Isotope Laboratories, and for air sensitive usage, dried over calcium hydride and sodium, respectively, freeze- 34

pump-thawed three times, vacuum transferred, and stored over molecular sieves in a nitrogen-filled glovebox. All other solvents were purchased from either Fisher or Sigma-

Aldrich. n-Butyllithium (1.6 M in hexane), (allyl)palladium(II) chloride dimer, diphenylchlorophosphine, lithium aluminum hydride, and silver triflate were purchased from Strem and applied without further purification. Phosphorus oxychloride, pyrrolidine, morpholine, 1,2,3,4-tetrahydroisoquinoline, 4-chloroaniline, and 4- ethylaniline were purchased from Acros; cyclopentanone and dimethyl-4- phenylenediamine were supplied by Alfa Aesar. Piperidine, p-toluidine, and cyclohexylallene were purchased from Aldrich. Aniline and 4-isopropylaniline were obtained from Fisher Scientific and Maybridge, respectively. All the substrates for catalytic reactions, including cyclohexylallene, pyrrolidine, piperidine, morpholine, and

1,2,3,4-tetrahydroisoquinoline, were dried over calcium hydride, freeze-pump-thawed three times, vacuum transferred and stored in the glovebox over molecular sieves. All other chemicals were used as received without further purification. 1H and 13C NMR data were obtained on a 600 MHz Varian Unity Inova, 600 MHz Avance III Bruker, or 400

MHz Varian VXRS NMR spectrometer at 599.9 MHz for 1H NMR and 150.8 for 13C

NMR with the first two spectrometers and at 399.95 MHz for 1H NMR and 100.56 MHz for 13C NMR with the VXRS spectrometer. All 31P NMR data were obtained on the 400

MHz VXRS NMR spectrometer at 161.90 MHz. 1H and 13C NMR shifts are reported relative to CHCl3 (7.26 ppm) and CDCl3 (77.2 ppm) or C6D5H (7.16 ppm) and C6D6

(128.1 ppm). 31P NMR data were externally referenced to 0.00 ppm with a 5% solution of H3PO4 in D2O. IR samples were prepared between NaCl plates as Nujol mulls and data were collected on a Perkin Elmer Spectrum 2 FT-IR spectrometer. Melting points were 35

determined with a capillary melting point apparatus (Uni-Melt) in sealed capillary tubes under nitrogen. Elemental analysis and high resolution mass spectrometry data were determined by Atlantic Microlab, Inc., Norcross, GA, USA and University of Illinois

Mass Spectrometry Laboratory, Urbana, IL, USA, respectively.

Alicyclic α,β-Unsaturated β-Chloroimines 1a-f: To diethyl ether (60 ml) was added activated 4Å molecular sieves, and this mixture was cooled to 0 oC before addition of chloroaldehyde. The para-substituted aniline (1.1 eq.) was added slowly and the mixture was stirred overnight. Reaction completion was monitored by 1H NMR spectroscopy. For the chloroimines 1a-d another portion of para-substituted aniline (0.2 eq.) was added after 12 h. After reaction completion, the solution was passed through a plug of silica to remove unreacted aniline, followed by drying over MgSO4 for 30 min before filtering over Celite. The solution containing chloroimine was concentrated under vacuum and degassed with nitrogen before use in the next step. Due to decomposition problems, α,β-unsaturated β-chloroimines could not be stored. Thus, they were used upon reaction completion immediately after this quick isolation protocol.

1 2-Chlorocyclopentene-1-(4-N,N-dimethylaminophenyl)imine (1a): H NMR (CDCl3):

3 3 8.50 (s, 1H), 7.20 (d, JH-H= 9.0 Hz, 2H), 6.72 (d, JH-H= 9.0 Hz, 2H), 2.97 (s, 6H), 2.82-

13 1 2.79 (m, 4H), 2.17-2.04 (m, 2H); C{ H} NMR (CDCl3): 150.8, 149.7, 141.3, 139.7,

136.4, 122.5, 112.8, 40.8, 39.6, 30.6, 20.9.

1 2-Chlorocyclopentene-1-(4-methylphenyl)imine (1b): H NMR (CDCl3): 8.45 (s, 1H),

3 3 7.17 (d, JH-H= 8.2 Hz, 2H), 7.07 (d, JH-H= 8.2 Hz, 2H), 2.82-2.75 (m, 4H), 2.35 (s, 3H),

13 1 2.12-1.96 (m, 2H); C{ H} NMR (CDCl3): 154.3, 153.7, 149.7, 141.9, 136.1, 129.7,

121.0, 39.7, 30.4, 21.0, 20.9.

1 2-Chlorocyclopentene-1-(4-ethylphenyl)imine (1c): H NMR (CDCl3): 8.46 (s, 1H),

3 3 3 7.20 (d, JH-H= 8.0 Hz, 2H), 7.10 (d, JH-H= 8.0 Hz, 2H), 2.81-2.78 (m, 4H), 2.66 (q, JH-

3 13 1 H= 7.6 Hz, 2H), 2.09-2.02 (m, 2H), 1.25 (t, JH-H= 7.6 Hz, 3H); C{ H} NMR (CDCl3):

154.4, 153.7, 142.5, 137.4, 136.2, 128.6, 121.1, 39.7, 30.5, 28.5, 21.2, 20.9.

1 2-Chlorocyclopentene-1-(4-isopropylphenyl)imine (1d): H NMR (CDCl3): 8.59 (s,

3 3 3 1H), 7.34 (d, JH-H= 8.4 Hz, 2H), 7.24 (d, JH-H= 8.4 Hz, 2H), 3.03 (sept, JH-H= 6.8 Hz,

3 13 1 1H), 2.94-2.89 (m, 4H), 2.20-2.13 (m, 2H), 1.38 (d, JH-H= 6.8 Hz, 6H); C{ H} NMR

(CDCl3): 154.5, 150.2, 147.1, 141.8, 136.3, 127.2, 121.1, 39.8, 33.8, 30.5, 24.2, 20.9.

1 2-Chlorocyclopentene-1-(phenyl)imine (1e): H NMR (CDCl3): 8.44 (s, 1H), 7.35-7.32

(m, 2H), 7.16-7.11 (m, 3H), 2.83-2.75 (m, 4H), 2.08-2.01 (m, 2H); 13C{1H} NMR

(CDCl3): 155.1, 144.0, 139.3, 138.3, 129.1, 126.1, 121.0, 39.7, 30.4, 20.9.

1 2-Chlorocyclopentene-1-(4-chlorophenyl)imine (1f): H NMR (CDCl3): 8.41 (s, 1H),

3 3 7.52 (d, JH-H= 8.4 Hz, 2H), 7.08 (d, JH-H= 8.4 Hz, 2H), 2.82-2.74 (m, 4H), 2.13-1.98 (m,

13 1 2H); C{ H} NMR (CDCl3): 155.3, 150.8, 143.1, 136.1, 131.7, 129.3, 122.4, 39.8, 30.4,

20.9.

3-Iminophosphine Ligands 2a-f: All the manipulations were performed under nitrogen atmosphere using Schlenk techniques. A solution of freshly prepared chloroimine (used in situ as a solution in ether) was degassed and cooled to 0 oC. To this was added LiPPh2 (1 eq.) dissolved in diethyl ether via cannula. The amount of LiPPh2 was calculated on the basis of the mass of the chloroaldehyde used for the production of chloroimine. The mixture was stirred for 2 h, and then the reaction solution was filtered over Celite to remove LiCl formed in the reaction. The resulting solution was concentrated under vacuum and was kept under nitrogen at 21 oC overnight to give the

3IP ligand as a yellow solid. Subsequently, the supernatant was filtered and the solid residue was placed under vacuum to remove the volatiles. For ligands 2a and 2e, the solid residue was recrystallized in concentrated pentane to remove phosphine impurities.

Percent yields for the 3IP ligands 2a-f were calculated on the basis of the mass of starting chloroaldehyde.

2-Diphenylphosphinocyclopentene-1-(4-N,N-dimethylaminophenyl)imine (2a):

o 1 4 Yellow solid (2.258 g, 74%); mp 180-183 C; H NMR (CDCl3): 8.98 (d, JP-H= 4.0 Hz,

3 3 1H), 7.41-7.33 (m, 10H), 7.16 (d, JH-H= 9.0 Hz, 2H), 6.70 (d, JH-H= 9.0 Hz, 2H), 2.98-

2.95 (m, 2H), 2.96 (s, 6H), 2.44-2.40 (m, 2H), 1.93-1.88 (m, 2H); 13C{1H} NMR

3 2 1 (CDCl3): 154.3 (d, JP-C= 21.1 Hz), 152.9 (d, JP-C= 22.6 Hz), 149.7, 147.3 (d, JP-C= 21.1

1 2 3 Hz), 141.3, 136.6 (d, JP-C= 7.5 Hz), 133.3 (d, JP-C= 19.6 Hz), 128.7, 128.6 (d, JP-C= 6.0

3 2 31 1 Hz), 122.7, 112.9, 40.9, 37.7 (d, JP-C= 3.0 Hz), 34.2 (d, JP-C= 4.5 Hz), 22.8; P{ H}

NMR (CDCl3): -24.20; IR (Nujol): 3049(m), 2805(m), 1612(s), 1579(s), 1566(m),

1514(s), 1477(s), 1446(s), 1432(m), 1358(s), 1261(w), 1227(m), 1204(w), 1167(s),

1125(m), 1093(m), 1075(m), 1067(m), 1027(w), 998(w), 948(m), 820(s), 795(w),

-1 + 746(m), 702(m), 697(m) cm ; HRMS: m/z calcd for C26H28N2P 399.1990 [M+H] ; found: 399.1990.

2-Diphenylphosphinocyclopentene-1-(4-methylphenyl)imine (2b): Yellow solid

o 1 4 (1.952 g, 69%); mp 123-126 C; H NMR (CDCl3): 8.94 (d, JP-H= 4.2 Hz, 1H), 7.41-7.35

3 3 (m, 10H), 7.14 (d, JH-H= 8.4 Hz, 2H), 7.04 (d, JH-H= 8.4 Hz, 2H), 2.99-2.96 (m, 2H),

13 1 3 2.46-2.44 (m, 2H), 2.35 (s, 3H), 1.96-1.91 (m, 2H); C{ H} NMR (CDCl3): 156.4 (d, JP-

2 1 C= 22.6 Hz), 153.7 (d, JP-C= 21.1 Hz), 150.0, 149.8, 136.3 (d, JP-C= 9.1 Hz), 136.0,

1 2 3 133.3 (d, JP-C= 19.6 Hz), 129.8, 128.8, 128.7 (d, JP-C= 7.5 Hz), 121.2, 37.9 (d, JP-C= 3.0

2 3 31 1 Hz), 34.1 (d, JP-C= 6.0 Hz), 22.7 (d, JP-C= 1.5 Hz), 21.2; P{ H} NMR (CDCl3): -24.17;

IR (Nujol): 3053(m), 1663(w), 1614(w), 1584(m), 1570(m), 1519(m), 1502(m), 1433(s),

1378(s), 1348(w), 1325(w), 1306(w), 1278(m), 1260(m), 1214(w), 1193(w), 1179(w),

1168(w), 1157(w), 1090(m), 1068(m), 1027(m), 829(m), 814(m), 752(m), 744(m), 697(s)

-1 + cm ; HRMS: m/z calcd for C25H25NP 370.1725 [M+H] ; found: 370.1723.

2-Diphenylphosphinocyclopentene-1-(4-ethylphenyl)imine (2c): Pale yellow solid

o 1 4 (1.909 g, 65%); mp 123-125 C; H NMR (CDCl3): 8.94 (d, JP-H= 4.0 Hz, 1H), 7.42-7.34

3 3 (m, 10H), 7.17 (d, JH-H= 8.0 Hz, 2H), 7.06 (d, JH-H= 8.0 Hz, 2H), 2.99-2.95 (m, 2H),

3 3 2.64 (q, JH-H= 7.6 Hz, 2H), 2.46-2.42 (m, 2H), 1.96-1.89 (m, 2H), 1.23 (t, JH-H= 7.6 Hz,

13 1 3 2 3H); C{ H} NMR (CDCl3): 156.4 (d, JP-C= 21.1 Hz), 153.7 (d, JP-C= 19.6 Hz), 150.0,

1 1 2 149.9 (d, JP-C= 24.1 Hz), 142.4, 136.4 (d, JP-C= 9.1 Hz), 133.3 (d, JP-C= 18.1 Hz), 128.8,

3 3 2 128.7 (d, JP-C= 7.5 Hz), 128.6, 121.3, 37.9 (d, JP-C= 4.5 Hz), 34.1 (d, JP-C= 4.5 Hz),

31 1 28.6, 22.7, 15.8; P{ H} NMR (CDCl3): -24.21; IR (Nujol): 3064(m), 1609(w), 1581(w),

1571(w), 1499(m), 1477(m), 1462(m), 1433(m), 1415(w), 1377(m), 1348(w), 1261(s),

1091(s), 1058(s), 1021(s), 953(w), 939(w), 862(m), 835(m), 800(s), 754(m), 702(m),

-1 + 662(w) cm ; HRMS: m/z calcd for C26H27NP 384.1881 [M+H] ; found: 384.1885.

2-Diphenylphosphinocyclopentene-1-(4-isopropylphenyl)imine (2d): Yellow solid

o 1 4 (1.918 g, 63%); mp 124-125 C; H NMR (CDCl3): 8.94 (d, JP-H= 4.0 Hz, 1H), 7.41-7.34

3 3 (m, 10H), 7.19 (d, JH-H= 8.4 Hz, 2H), 7.06 (d, JH-H= 8.4 Hz, 2H), 2.99-2.95 (m, 2H),

3 3 2.90 (sept, JH-H= 6.8 Hz, 1H), 2.46-2.42 (m, 2H), 1.96-1.89 (m, 2H), 1.25 (d, JH-H= 6.8

13 1 3 2 Hz, 6H); C{ H} NMR (CDCl3): 156.5 (d, JP-C= 22.6 Hz), 153.8 (d, JP-C= 21.1 Hz),

1 1 2 150.1, 149.9 (d, JP-C= 22.6 Hz), 147.0, 136.4 (d, JP-C= 9.1 Hz), 133.3 (d, JP-C= 18.1 Hz),

3 3 2 128.8, 128.7 (d, JP-C= 7.5 Hz), 127.1, 121.3, 37.9 (d, JP-C= 3.0 Hz), 34.1 (d, JP-C= 4.5

31 1 Hz), 33.8, 24.2, 22.7; P{ H} NMR (CDCl3): -24.82; IR (Nujol): 3067(m), 2722(m),

1896(w), 1614(m), 1584(m), 1577(m), 1516(m), 1500(m), 1476(s), 1458(s), 1379(m),

1362(m), 1351(w), 1329(w), 1296(w), 1276(w), 1260(w), 1211(m), 1180(w), 1145(w),

1110(w), 1100(m), 1089(m), 1081(m), 1068(w), 1054(m), 1026(m), 1015(w), 999(w),

-1 + 861(w), 834(m), 746(s), 699(s) cm ; HRMS: m/z calcd for C27H29NP 398.2038 [M+H] ; found: 398.2036.

2-Diphenylphosphinocyclopentene-1-(phenyl)imine (2e): Yellow solid (1.933 g, 71%);

o 1 4 mp 120-122 C; H NMR (CDCl3): 8.93 (d, JP-H=4.0 Hz, 1H), 7.45-7.30 (m, 10H), 7.25-

7.08 (m, 5H), 3.02-2.95 (m, 2H), 2.50-2.42 (m, 2H), 1.98-1.89 (m, 2H); 13C{1H} NMR

3 2 1 (CDCl3): 157.1 (d, JP-C= 21.1 Hz), 153.6 (d, JP-C= 19.6 Hz), 152.4, 150.6 (d, JP-C= 22.6

1 2 3 Hz), 136.3 (d, JP-C= 7.5 Hz), 133.3 (d, JP-C= 19.6 Hz), 129.1, 128.8, 128.7 (d, JP-C= 6.0

3 2 31 1 Hz), 126.1, 121.3, 37.9 (d, JP-C= 3.0 Hz), 34.1 (d, JP-C= 4.5 Hz), 22.7; P{ H} NMR

(CDCl3): -24.20; IR (Nujol): 3064(m), 1602(m), 1570(s), 1501(w), 1483(m), 1475(s),

1465(s), 1431(s), 1377(m), 1348(w), 1328(w), 1308(w), 1261(w), 1177(w), 1091(m),

-1 1071(m), 1023(w), 760(m), 745(s), 699(s), 684(m) cm ; HRMS: m/z calcd for C24H23NP

356.1568 [M+H]+; found: 356.1566.

2-Diphenylphosphinocyclopentene-1-(4-chlorophenyl)imine (2f): Yellow solid (2.269

o 1 4 g, 76%); mp 132-133 C; H NMR (CDCl3): 8.86 (d, JP-H= 4.2 Hz, 1H), 7.40-7.35 (m,

3 3 10H), 7.28 (d, JH-H= 9.0 Hz, 2H), 7.02 (d, JH-H= 9.0 Hz, 2H), 2.96-2.93 (m, 2H), 2.46-

13 1 3 2.44 (m, 2H), 1.95-1.90 (m, 2H); C{ H} NMR (CDCl3): 157.4 (d, JP-C= 21.1 Hz),

2 1 1 153.2 (d, JP-C= 19.6 Hz), 151.5 (d, JP-C= 22.6 Hz), 150.9, 136.1 (d, JP-C= 9.1 Hz), 133.3

2 3 3 (d, JP-C= 18.1 Hz), 131.6, 129.2, 128.9, 128.7 (d, JP-C= 6.0 Hz), 122.6, 38.1 (d, JP-C= 4.5

2 31 1 Hz), 34.0 (d, JP-C= 6.0 Hz), 22.7; P{ H} NMR (CDCl3): -23.91; IR (Nujol): 3414(m),

1888(w), 1602(s), 1581(s), 1480(s), 1466(m), 1433(m), 1402(w), 1377(w), 1260(w),

1204(w), 1100(m), 1089(s), 1070(w), 1026(w), 1009(m), 825(w), 812(w), 746(m),

-1 + 704(m), 698(s) cm ; HRMS: m/z calcd for C24H22ClNP 390.1178 [M+H] ; found:

390.1174.

[(3IP)Pd(allyl)]OTf catalysts (3a-f): Solutions of 3-iminophosphine ligand (1.1 eq.) and allylpalladium chloride dimer (0.5 eq.) in dichloromethane were combined at ambient temperature and stirred overnight. The resulting solution was placed under vacuum to remove all the volatiles and the residue washed with pentane. The solid

residue was then dissolved in dichloromethane and concentrated to form a saturated solution, followed by layering with pentane to induce precipitation. The solution was filtered to yield the catalyst, which was washed with pentane and dried under vacuum before transferring into the glovebox. Percent yields for the [(3IP)Pd(allyl)]OTf precatalysts were calculated on the basis of the allylpalladium chloride dimer used.

[(2-Diphenylphosphinocyclopentene-1-(4-N,N-dimethylaminophenyl)imine)Pd

o 1 (allyl)] OTf (3a): Red solid (561 mg, 59%); mp 91 C dec; H NMR (CDCl3): 7.96 (d,

4 3 JP-H= 1.8 Hz, 1H), 7.59-7.49 (m, 10H), 7.28 (d, JH-H= 9.0 Hz, 2H), 6.78 (b, 2H), 5.87-

3 3 5.80 (m, 1H), 4.15 (d, JH-H= 7.2 Hz, 1H), 3.94 (m, 1H), 3.33 (d, JH-H= 5.4 Hz, 1H), 3.06-

3.01 (m, 2H), 3.03 (s, 6H), 2.63-2.58 (m, 3H), 2.10-2.01 (m, 2H); 13C{1H} NMR

3 2 4 (CDCl3): 159.8 (d, JP-C= 7.5 Hz), 153.8 (d, JP-C= 18.1 Hz), 135.2, 133.1 (d, JP-C= 14.3

4 1 2 Hz), 132.6 (d, JP-C= 13.2 Hz), 132.0 (d, JP-C= 31.5 Hz), 130.6 (d, JP-C= 11.0 Hz), 129.8

3 1 1 2 (d, JP-C= 11.0 Hz), 129.1 (d, JP-C= 49.5 Hz), 128.8 (d, JP-C= 47.3 Hz), 123.0 (d, JP-C=

2 2 5.5 Hz), 122.8, 122.1, 120.0, 112.6, 89.1 (d, JP-C= 28.6 Hz), 54.7 (d, JP-C= 3.3 Hz), 40.5,

2 3 31 1 39.0 (d, JP-C= 12.1 Hz), 36.1, 22.8, 22.5 (d, JP-C= 5.5 Hz); P{ H} NMR (CDCl3):

13.11; IR (Nujol): 1615(w), 1576(w), 1505(w), 1463(m), 1296(s), 1231(s), 1167(s),

1100(m), 1021(s), 893(w), 844(w), 802(w), 749(w), 721(w), 697(w), 635(s) cm-1.

[(2-Diphenylphosphinocyclopentene-1-(4-methylphenyl)imine)Pd(allyl)]OTf (3b):

o 1 4 Dark brown solid (610 mg, 62%); mp 98 C dec; H NMR (CDCl3): 8.02 (d, JP-H= 2.4

3 3 Hz, 1H), 7.62-7.48 (m, 10H), 7.23 (d, JH-H= 7.8 Hz, 2H), 7.19 (d, JH-H= 7.8 Hz, 2H),

3 5.80-5.73 (m, 1H), 3.97-3.95 (m, 1H), 3.88-3.84 (m, 1H), 3.40 (d, JH-H= 5.4 Hz, 1H),

3 3.08-2.98 (m, 2H), 2.65-2.58 (m, 2H), 2.46 (d, JH-H= 12.0 Hz, 1H), 2.39 (s, 3H), 2.09-

13 1 3 2.02 (m, 2H); C{ H} NMR (CDCl3): 163.0 (d, JP-C= 7.5 Hz), 155.5, 138.4, 136.5 (d,

1 4 4 2 JP-C= 33.2 Hz), 133.1 (d, JP-C= 13.6 Hz), 132.6 (d, JP-C= 12.1 Hz), 131.1 (d, JP-C= 34.7

2 3 1 Hz), 130.9, 130.1 (d, JP-C= 15.1 Hz), 129.6 (d, JP-C= 12.1 Hz), 129.3 ( JP-C= 52.8 Hz),

1 2 2 128.6 ( JP-C= 51.3 Hz) 123.0 (d, JP-C= 4.5 Hz), 122.7, 121.3, 120.8, 89.2 (d, JP-C= 28.7

2 2 3 Hz), 54.9 (d, JP-C= 4.5 Hz), 38.9 (d, JP-C= 12.1 Hz), 36.1, 22.4 (d, JP-C= 4.5 Hz), 21.1;

31 1 P{ H} NMR (CDCl3): 12.83; IR (Nujol): 1641(w), 1614(w), 1574(w), 1503(m),

1462(s), 1440(m), 1377(m), 1296(s), 1260(s), 1156(m), 1098(m), 1021(s), 863(w),

-1 803(m), 747(m), 721(w), 695(m) cm ; Anal. Calcd for C29H29F3NO3PPdS·3CH2Cl2: C,

41.74. H, 3.83. N, 1.52. Found: C, 42.36. H, 3.98. N, 1.67.

[(2-Diphenylphosphinocyclopentene-1-(4-ethylphenyl)imine)Pd(allyl)]OTf (3c):

o 1 4 Yellow solid (522 mg, 54%); mp 88-90 C; H NMR (CDCl3): 8.01 (d, JP-H= 2.4 Hz,

3 3 1H), 7.62-7.52 (m, 10H), 7.26 (d, JH-H= 8.4 Hz, 2H), 7.24 (d, JH-H= 8.4 Hz, 2H), 5.83- 44

3 5.76 (m, 1H), 3.96-3.91 (m, 2H), 3.37 (d, JH-H= 5.4 Hz, 1H), 3.08-3.03 (m, 2H), 2.68 (q,

3 3 JH-H= 7.8 Hz, 2H), 2.65-2.60 (m, 3H), 2.11-2.03 (m, 2H), 1.24 (t, JH-H= 7.8 Hz, 3H);

13 1 3 2 C{ H} NMR (CDCl3): 162.7 (d, JP-C= 7.5 Hz), 155.7, 153.5 (d, JP-C= 18.1 Hz), 144.4,

1 4 4 136.5 (d, JP-C= 33.2 Hz), 133.1 (d, JP-C= 13.6 Hz), 132.8 (d, JP-C= 12.1 Hz), 132.0 (d,

2 3 1 1 JP-C= 22.6 Hz), 129.8 (d, JP-C= 10.6 Hz), 129.1 (d, JP-C= 48.3 Hz), 128.7, 128.5 (d, JP-

3 2 C= 45.3 Hz), 123.0 (d, JP-C= 6.0 Hz), 122.2, 121.1, 120.1, 89.2 (d, JP-C= 28.7 Hz), 54.7

2 2 3 (d, JP-C= 3.0 Hz), 38.9 (d, JP-C= 10.6 Hz), 36.1, 28.5, 22.4 (d, JP-C= 4.5 Hz), 15.6;

31 1 P{ H} NMR (CDCl3): 12.73; IR (Nujol): 2293(w), 1612(w), 1574(w), 1502(m),

1481(m), 1461(s), 1437(s), 1377(m), 1260(s), 1222(s), 1183(m), 1146(s), 1099(s),

1073(m), 1029(s), 998(m), 963(w), 841(w), 802(w), 751(m), 696(m) cm-1; Anal. Calcd for C30H31F3NO3PPdS: C, 52.99. H, 4.60. N, 2.06. Found: C, 52.45. H, 4.75. N, 2.06.

[(2-Diphenylphosphinocyclopentene-1-(4-isopropylphenyl)imine)Pd(allyl)]OTf (3d):

o 1 4 Brown solid (495 mg, 52%), mp 93 C dec; H NMR (CDCl3): 8.01 (d, JP-H= 2.4 Hz,

3 1H), 7.66-7.52 (m, 10H), 7.26 (s, 4H), 5.82-5.76 (m, 1H), 3.97-3.91 (m, 2H), 3.37 (d, JH-

3 3 H= 5.4 Hz, 1H), 3.08-3.02 (m, 2H), 2.94 (sept, JH-H= 6.6 Hz, 1H), 2.66 (d, JH-H= 12.0

3 13 1 Hz, 1H), 2.64-2.60 (m, 2H), 2.10-2.03 (m, 2H), 1.25 (d, JH-H= 6.6 Hz, 6H); C{ H}

3 2 NMR (CDCl3): 162.8 (d, JP-C= 6.0 Hz), 155.8, 153.5 (d, JP-C= 18.1 Hz), 149.1, 136.5 (d,

1 4 4 2 JP-C= 33.2 Hz), 133.1 (d, JP-C= 13.6 Hz), 132.7 (d, JP-C= 15.1 Hz), 132.0 (d, JP-C= 22.6

3 1 1 Hz), 129.8 (d, JP-C= 12.1 Hz), 129.5 (d, JP-C= 34.0 Hz), 128.8, 128.7 (d, JP-C= 36.9 Hz),

2 2 2 127.3, 123.0 (d, JP-C= 4.5 Hz), 121.5, 121.1, 89.2 (d, JP-C= 28.7 Hz), 54.7 (d, JP-C= 4.5 45

2 3 31 1 Hz), 38.9 (d, JP-C= 12.1 Hz), 36.1, 33.9, 24.1, 22.4 (d, JP-C= 6.0 Hz); P{ H} NMR

(CDCl3): 12.72; IR (Nujol): 1611(m), 1574(m), 1501(m), 1482(m), 1437(s), 1378(m),

1366(m), 1259(s), 1222(s), 1148(s), 1099(s), 1028(s), 999(s), 922(w), 863(m), 838(m),

-1 801(s), 749(m), 696(m), 635(s) cm ; Anal. Calcd for C31H33F3NO3PPdS·0.5CH2Cl2: C,

51.37. H, 4.65. N, 1.90. Found: C, 50.99. H, 4.98. N, 1.91.

[(2-Diphenylphosphinocyclopentene-1-(phenyl)imine)Pd(allyl)]OTf (3e): Brown solid

o 1 4 (600 mg, 60%); mp 102-104 C; H NMR (CDCl3): 8.02 (d, JP-H= 2.4 Hz, 1H), 7.60-7.45

(m, 8H), 7.43-7.38 (m, 2H), 7.33-7.24 (m, 5H), 5.80-5.74 (m, 1H), 3.91-3.86 (m, 2H),

3 3 3.37 (d, JH-H= 5.4 Hz, 1H), 3.08-3.03 (m, 2H), 2.66 (d, JH-H= 12.6 Hz, 1H), 2.64-2.59

13 1 3 (m, 2H), 2.10-2.03 (m, 2H); C{ H} NMR (CDCl3): 163.2 (d, JP-C= 6.0 Hz), 157.8,

2 1 4 153.4 (d, JP-C= 18.1 Hz), 136.9 (d, JP-C= 33.2 Hz), 133.1 (d, JP-C= 13.6 Hz), 132.7 (d,

4 2 3 1 JP-C= 13.6 Hz), 132.0 (d, JP-C= 22.6 Hz), 129.8 (d, JP-C= 12.1 Hz), 129.5, 128.9 (d, JP-

1 2 C= 49.8 Hz), 128.4 (d, JP-C= 48.3 Hz), 128.0, 123.0 (d, JP-C= 7.5 Hz), 122.1, 121.1,

2 2 2 119.9, 89.0 (d, JP-C= 28.7 Hz), 54.8 (d, JP-C= 3.0 Hz), 38.9 (d, JP-C= 10.6 Hz), 36.2, 22.4

3 31 1 (d, JP-C= 6.0 Hz); P{ H} NMR (CDCl3): 12.70; IR (Nujol): 1570(w), 1482(w), 1463(s),

1438(m), 1377(m), 1261(s), 1222(m), 1148(m), 1099(m), 1029(s), 999(w), 800(w),

-1 774(w), 752(w), 736(w), 695(m) cm ; Anal. Calcd for C28H27F3NO3PPdS: C, 51.58. H,

4.17. N, 2.15. Found: C, 51.21. H, 4.45. N, 2.32.

[(2-Diphenylphosphinocyclopentene-1-(4-chlorophenyl)imine)Pd(allyl)]OTf (3f):

o 1 4 Brown solid (663 mg, 69%); mp 109 C dec; H NMR (CDCl3): 8.02 (d, JP-H= 2.4 Hz,

3 3 1H), 7.61-7.51 (m, 10H), 7.38 (d, JH-H= 9.0 Hz, 2H), 7.34 (d, JH-H= 9.0 Hz, 2H), 5.80-

3 5.73 (m, 1H), 3.95-3.93 (m, 1H), 3.92-3.88 (m, 1H), 3.36 (d, JH-H= 4.8 Hz, 1H), 3.09-

3 3.03 (m, 2H), 2.66 (d, JH-H= 12.6 Hz, 1H), 2.63-2.59 (m, 2H), 2.08-2.03 (m, 2H);

13 1 3 2 C{ H} NMR (CDCl3): 163.8 (d, JP-C= 7.5 Hz), 156.2, 153.5 (d, JP-C= 16.6 Hz), 137.2

1 4 4 (d, JP-C= 33.2 Hz), 133.6, 133.1 (d, JP-C= 15.1 Hz), 132.8 (d, JP-C= 13.6 Hz), 132.0 (d,

2 3 1 JP-C= 19.6 Hz), 130.4, 129.8 (d, JP-C= 10.6 Hz), 129.5, 129.0 (d, JP-C= 48.3 Hz), 128.4

1 3 2 (d, JP-C= 48.3 Hz), 123.0 (d, JP-C= 7.5 Hz), 122.8, 121.5, 88.9 (d, JP-C= 28.7 Hz), 54.9

2 2 3 31 1 (d, JP-C= 3.0 Hz), 38.9 (d, JP-C= 12.1 Hz), 36.2, 22.4 (d, JP-C= 6.0 Hz); P{ H} NMR

(CDCl3): 12.62; IR(Nujol): 1611(w), 1575(w), 1483(s), 1463(s), 1438(s), 1377(m),

1337(m), 1315(m), 1261(s), 1231(s), 1208(s), 1155(s), 1099(s), 1029(s), 1012(s), 999(m),

983(m), 860(w), 832(w), 747(m), 720(w), 695(m) cm-1; Anal. Calcd for

C28H26ClF3NO3PPdS·CH2Cl2: C, 45.16. H, 3.66. N, 1.82. Found: C, 44.37. H, 3.69. N,

1.94.

General Procedure for the Catalytic Hydroamination Screening of Catalysts

3a-f: All manipulations were performed in an NMR tube inside a nitrogen-filled glovebox. Cyclohexylallene (61 mg, 0.50 mmol) was added to a mixture of C6H6 (0.50 mmol as internal standard), secondary amine (0.50 mmol), [(3IP)Pd(allyl)]OTf (0.025

mmol) and deuterated benzene (800 µl). The ratio of each substrate to hydroamination product was monitored by 1H NMR spectroscopy.

2.4 Conclusion

On the basis of our previous reports, as well as the Hammett study and deuterium labeling experiments described, we have proposed a new catalytic cycle for our 3IP- palladium-catalyzed intermolecular hydroamination. The electronics of the imine unit of the 3IP ligand significantly affect the catalytic activity observed. More specifically, the electron density on the nitrogen of the imine is significant in two ways. First, in the step involving coordination of the substrate amine, less electron density on the iminic nitrogen if favorable to make it less basic and thus easier for the free amine to displace the imine from palladium. On the other hand, in the next step, more electron density on the iminic nitrogen is necessary to help in deprotonation of the coordinated amine.

Chapter 3

Synthesis of [(3-Iminophosphine)nickel(allyl)]OTf Complexes and Their Catalytic Activity for the Hydroamination of Allenes

3.1 Introduction

Hydroamination, commonly noted as one of the most challenging and interesting addition reactions, is defined as N-H bond addition to a C-C multiple bond and is unobtainable without a catalyst, except in rare cases where the unsaturated substrate is highly activated. The distinctly negative entropy term coupled with only modest exothermicity explains the difficult nature of direct intermolecular hydroamination.60

Despite its underlying complexity, the significance of this process relies on the broad potential utilization of the resulting products in pharmaceuticals and specialty chemicals.60, 62 Although many early and late transition metals can promote hydroamination of C-C multiple bonds, due to issues involving substrate scope, cost, toxicity, and oxophilicity, many known reactive metal complexes are unsatisfactory for industrial utilization.60 These factors have led to the extensive investigation of late transition metals such as Ru, Rh, Pd, Ir, Pt and Au as some of the most promising candidates for broad application.59, 60, 99, 101, 104, 115, 117, 118, 123, 182, 200, 218-224 However, despite the demonstration of excellent reactivity profiles, one remaining unsolved 49

problem is the cost of catalyst since these highly active late transition metal catalysts for hydroamination are very expensive. Thus, the development of a first row late transition metal hydroamination catalyst derived from Ni or Cu would be quite favorable. Recently, copper has shown promise in catalysis of C-N bond forming reactions, although direct hydroamination using copper has only recently emerged while the overall atom economy is low in other copper-based amination reactions due to the formation of byproducts.58,

225-229 Curiously, nickel-based catalysts have not been the subject of recent reports. With common accessible oxidation states of 0, +1, +2, and +3, it seems likely that the rich chemistry of nickel would include applications in hydroamination, since two unit oxidation state toggles are common in direct metal-catalyzed hydroamination.60, 230

However, surprisingly, virtually all reports of nickel-catalyzed hydroamination to date are limited to highly activated substrates or require very high temperatures. These nickel- catalyzed transformations, as studied by Togni,93-95 Zargarian96, 97 and Garcia,98 support a likely mechanism for nickel-catalyzed hydroamination of activated C-C multiple bonds

(mainly acrylonitrile and related compounds) based on the electrophilicity of the Ni center. In research moving beyond these highly activated systems, Ackermann has described the intramolecular hydroamination of alkynes to form indoles.231

Unfortunately, one drawback of Ackermann’s system is the high temperature (120 oC) needed to obtain significant reactivity. The only well-defined report of nickel-catalyzed intermolecular hydroamination of unactivated C-C multiple bonds is a single paper by

Hartwig in which the intermolecular hydroamination of 1,3-dienes to form allylamine products is reported.129

Although nickel-catalyzed C-N bond formation has attracted much interest, direct hydroamination catalyzed by nickel remains an unsolved challenge.232-235 It is clear that metal-catalyzed hydroamination processes are dependent on both the metal utilized and the effects of the ancillary ligands employed. Both features impact the overall efficiency and operable mechanism in known systems. In our recent work involving the mechanistic study of palladium-catalyzed allene hydroamination, we showed that electronic effects in the supporting 3-iminophosphine (3IP) ligands often dictate the rate-limiting step in the mechanism for this process.115 With this understanding of ligand effects, we felt well poised to address the challenging reactivity of nickel analogues based on our previously reported palladium catalysts, especially as applied to allene hydroamination catalysis.

Herein, we describe the first example of nickel-based allene hydroamination through the use of cationic [(3-iminophosphine)nickel(allyl)]+ complexes.

3.2 Results and Discussion

Synthesis of Nickel Complexes: Overall, the synthesis of allylnickel complexes proceeded similarly to our reported palladium analogues,114, 182 except for the fact that usage of a non-polar solvent is crucial in some steps to obtain the desired nickel complexes (Table 2). Attempts to use other solvents in the complexation reaction of the allylnickelbromide dimer with the 3IP ligand, such as diethyl ether, tetrahydrofuran, dichloromethane or acetonitrile, led to intractable mixtures. As previously reported, allylnickelhalide dimers are only stable in nonpolar solvents, undergoing ligand redistribution/disproportionation reactions in more polar environments.236 Once nickel complexes were synthesized, they were characterized by NMR spectroscopy and 51

elemental analysis. Suitable crystals of 4b were grown from a saturated solution of the complex in tetrahydrofuran layered by pentane. The structure was solved via direct methods (Figure 10).

Table 2. Cationic [(3IP)Ni(allyl)]+ complexes.

Ni complex Isolated yield (%) R’=tButyl R=Phenyl n=1 4a 87

R’=2,6-Xylyl R=Phenyl n=1 4b 85

R’=2,6-Xylyl R=tButyl n=1 4c 82

R’=2,6-Xylyl R=Phenyl n=2 4d 91

Figure 11. Crystal structure of 4b (50% thermal ellipsoids); hydrogen atoms, triflate anion and cocrystallized solvent (THF) have been omitted for clarity; Selected bond distances (Å) and bond angle (deg): Ni-P, 2.174; Ni-N, 1.920; P-Ni-N, 99.3.

Catalytic Hydroamination Using Nickel Complexes: Once the desired allylnickel complexes were isolated, their reactivity in the catalytic hydroamination of allenes was explored. As a means to investigate catalyst activation, equimolar amounts of nickel complex 4b and thiomorpholine were added to an NMR tube with C6D6 as solvent, and the reaction progress was observed every 10 minutes. This time-resolved 1H NMR data showed that after coordination of the secondary amine to the nickel precatalyst, the allyl ligand peaks steadily diminished as N-allylthiomorpholine product peaks (the catalyst activation product) appeared (Figure 11).

Figure 12. Time-resolved 1H NMR spectra of equimolar reaction between 4b and thiomorpholine (recorded every 10 minutes).

A similar stoichiometric reaction between 4b and indoline led smoothly to the analogous N-allylindoline product (Scheme 17). The putative nickel hydride concurrently formed in this reaction is unstable, decomposing in the absence of allene substrate and eluding adequate characterization in our hands.

Scheme 17. Reaction of 4b with secondary amines.

We previously observed a similar catalyst activation/first turnover product in palladium analogues of these nickel complexes, leading to their allene hydroamination activity.115 Thus, we set out to examine the catalytic activity of these newly synthesized nickel complexes in the hydroamination of mono-substituted allenes. Cyclohexylallene served as the allene precursor and was treated with a variety of amines (Table 3).

Secondary amines functioned well in this system, forming linear allylamine products in moderate to good yields, while primary amines of various types were invariably found to be unreactive.

Table 3. Hydroamination of cyclohexylallene catalyzed by 4b.a

Entry HNR1R2 Product Isolated yield (%)

1 67

2 52

3 71

4 91

5 87

6 50

7 39

8 92

9 53b

10 84

7j 11 - -

12 - -

13 - -

14 - -

15 - - 16 - -

a Reactions were performed in small vials; toluene (2 ml) was added to 4b (0.025 mmol, 5 mol%), followed by addition of amine (2 mmol, 4 eq.) and cyclohexylallene (0.5 mmol, 1 eq.). b Catalyst loading was increased to 0.05 mmol (10 mol%) and allowed to stir for 72 hours.

Although cyclooligomerization and polymerization of allenes is well-known,237,

238 very little of such byproducts was detected after 48 hours. During reaction optimization, it was found that using coordinating solvents (tetrahydrofuran, acetonitrile, or dioxane) resulted in lower conversions, possibly due to coordinative competition with the substrate amine. This was also examined through an NMR scale catalytic reaction in

which cyclohexylallene, thiomorphine and triethylamine (1 eq., 1 eq., and 2 eq., respectively) were allowed to react in the presence of 2.5 mol% of 4b. As observed by frequent 1H NMR spectra of the mixture, only 10% conversion after 30 h was detected, while 25% conversion was obtained in only 12 hours without triethylamine. Thus, it was concluded that coordination of the substrate amine plays a key role in this catalytic process, which is especially evident in comparison of entries 8 and 9 with methylindoline having less reactivity than indoline due to steric hinderance. Such effects were also observed in the related Pd catalysts.182

The substrate scope of this system was further investigated via hydroamination of additional mono-substituted allenes (6b, 6c and 6d) with secondary amines (Table 4). As with cyclohexylallene, all examples resulted in regioselective hydroamination of the allene to form the linear allylamine product as primarily the E isomer in moderate to good yields.

Table 4. Hydroamination of nhexyl-, nbutyl- and benzylallene catalyzed by 4b.a

8a (63%) 8b (82%)

8c (93%) 8d (90%)

8e (80%) 8f (91%)

9a (75%) 9b (60%)

9c (82%) 9d (79%)

9e (76%) 9f (79%)

10a (91%) 10b (83%)

10c (81%) 10d (81%) 59

10e (79%) 10f (77%) a Reactions were performed in small vials; toluene (2 ml) was added to 4b (0.05 mmol, 10 mol%), followed by addition of amine (2 mmol, 4 eq.) and allene (0.5 mmol, 1 eq.).

Despite a commonly believed misconception, mono-substituted allenes are readily available starting materials, easily generated from commercially available mono- substituted alkenes. One synthetic route to accomplish this is by treatment of alkenes with a dibromocarbene reagent to yield a dibromocyclopropane intermediate, followed by reaction with a Grignard reagent to open this three-membered ring and utilize these carbon atoms as the allene core.239 The allylamines subsequently formed by hydroamination are then of great interest in pharmaceuticals, while alternate synthetic methods to obtain these products are often less efficient and lower yielding.84

In one further effort to expand substrate scope, 1,1-dimethylallene was subjected to hydroamination. Reaction monitoring revealed that longer reaction times were required to obtain good yields in the hydroamination of 1,1-dimethylallene at room temperature

(Table 5). Performing the reaction at higher temperatures unfortunately led to the formation of complex mixtures of products, rather than merely increasing reaction rate.

Table 5. Hydroamination of 1,1-dimethylallene catalyzed by 4b.a

11a (63%) 11b (83%)

11c (80%) 11d (90%)

11e (68%) 11f (78%) a Reactions were performed in small vials; toluene (2 ml) was added to 4b (0.05 mmol, 10 mol%), followed by addition of amine (2 mmol, 4 eq.) and allene (0.5 mmol, 1 eq.).

Mechanistically, the preliminary results reported herein show that cationic

[(3IP)Ni(allyl)]+ complexes behave similarly to their palladium analogues upon treatment with secondary amines. That is, coordination of a secondary amine leading to transient formation of a nickel-amido species constitutes a plausible activation pathway. Then, reductive elimination of an N-allylamine followed by oxidative ligation of the iminium proton to the nickel complex results in the active nickel hydride species, producing the corresponding first turnover products 5a and 5b (Scheme 18). Recently, Mashima

proposed a similar intramolecular reductive elimination of amido and allyl units instead of nucleophilic attack on the allyl unit of a nickel complex as one of the key steps in the catalytic amination of allylic alcohols. Utilization of these inner sphere mechanisms, rather than ligand attack mechanisms, seems to fit well in several recent reports as well as the chemistry presented herein.115, 240, 241

Scheme 18. Activation of the nickel precatalyst in the presence of amine.

3.3 Experimental Section

General Methods and Instrumentation: All manipulations were performed under a nitrogen atmosphere, using either Schlenk techniques or in a glovebox. All 3- iminophosphine ligands were synthesized via the reported procedures.114 All required solvents (purchased from either Fisher or Sigma-Aldrich) were dried and degassed using standard techniques before use. Amines for catalytic hydroamination reactions were purchased from Sigma-Aldrich and dried neat (liquid amines) or as a solution in diethylether (solid amines) over calcium hydride and filtered under nitrogen, degassed, and volatiles were removed under vacuum. Volatile amines were transferred under static vacuum after they were freeze-pump-thawed three times. CDCl3 and C6D6 were purchased from Cambridge Isotope Laboratories and, for air-sensitive usage, dried over calcium hydride and sodium, respectively, freeze-pump-thawed three times, vacuum- 62

transferred, and stored over molecular sieves in a nitrogen-filled glovebox.

Cyclohexylallene and dimethylallene were supplied by Sigma-Aldrich and Santa Cruz

Biotechnology and used in a glovebox without further purification. 1H and 13C NMR data were obtained on a 600 MHz Varian Unity Inova, 600 MHz Avance III Bruker, or 400

MHz Varian VXRS NMR spectrometer at 599.9 MHz for 1H NMR and 150.8 MHz for

13C NMR with the first two spectrometers and at 399.95 MHz for 1H NMR and 100.56

MHz for 13C NMR with the VXRS spectrometer. All 31P NMR and 19F NMR data were obtained on the 400 MHz VXRS NMR spectrometer at 161.90 MHz and 376.29 MHz,

1 13 respectively. H and C NMR shifts are reported relative to CHCl3 (7.26 ppm) and

CDCl3 (77.2 ppm) or C6D5H (7.16 ppm). FT-IR data were obtained neat on a Perkin-

Elmer Spectrum 2 FTIR spectrometer. Melting points were determined with a capillary melting point apparatus (Uni-Melt) in sealed capillary tubes under nitrogen. Elemental analyses were determined by Atlantic Microlab, Inc., Norcross, GA, USA, and high resolution mass spectrometry data were acquired at the University of Toledo Mass

Spectrometry Laboratory, Toledo, OH, USA.

Synthesis of the Complexes 4a-d: Ni(cod)2 was synthesized via the reported procedure via reduction of Ni(acac)2 by DIBAL in the presence of 1,5-cyclooctadiene

242 and isolated as a light yellow powder. To a slurry of Ni(cod)2 (3.6 mmol, 1.0 g, 1 eq.) in pentane, allylbromide (5.4 mmol, 0.47 ml, 1.5 eq.) was added at -78 oC and allowed to stir at 0 oC for half an hour. The iminophosphine ligand (3.6 mmol, 1 eq.) was dissolved in 20 ml of pentane, cannula-transferred to the reaction mixture at room temperature, and stirred for half an hour. Reaction progress is monitored by formation of a precipitate at this step while the dark red color of allylnickelbromide disappears. The solution was 63

cannula-filtered and the light yellow precipitate was washed with pentane to remove organics. Without further characterization, to the formed complex dissolved in 10 ml of dichloromethane was added a slurry of silver triflate (3.8 mmol, 1.05 eq.) in 15 ml of dichloromethane, and this was stirred for two hours. The dark-colored solution was cannula-filtered and volatiles were removed under vacuum to complete dryness, followed by washing with small portions of pentane and diethyl ether. The powder was characterized as the product.

Synthesis of Allenes: Allenes 6b, 6c and 6d were synthesized via a procedure reported previously from the corresponding alkene in quantitative yields.239 After isolation, they were dried over calcium hydride, freeze-pump-thawed two times, distilled under static vacuum and transferred to the glovebox. 6d was reported previously.243 6b and 6c were characterized by 1H and 13C NMR.

Catalytic Reactions and Isolation of Hydroamination Products: All catalytic reactions were set up inside a nitrogen-filled glovebox in 20 ml screw-cap vials. Nickel catalyst 4b (0.025 or 0.050 mmol, 5 or 10 mol%, 15.8 or 31.6 mg) was added to the vial, followed by the addition of 2 ml of toluene. Amine (2 mmol, 4 eq.) was added to the mixture (partially soluble catalyst fully dissolves in toluene after addition of amine) and after five minutes, allene (0.5 mmol, 1 eq.) was added. The vial was capped and allowed to stir. After the reaction time, volatiles were removed under vacuum and the crude product was extracted into hexane/diethyl ether (50:50 mixture), pumped down and purified by flash chromatography (hexane:ethyl acetate, 90:10) using a small silica column. In some cases, diethyl ether or ethyl acetate was used to wash the product off the column. All hydroamination products were isolated as either colorless or pale yellow oils, 64

except 7g, 10b and 10c, which were white solids at ambient temperature. All these compounds were characterized as the major E isomer formed by 1H NMR, 13C NMR and high resolution mass spectrometry.

Isolation of First Turnover Products: To a 20 ml screw-cap vial, 4b (0.3 mmol,

189.6 mg, 1 eq.) and toluene (4 ml) were added, followed by addition of the secondary amine (1.2 mmol, 4 eq.). The mixture was allowed to stir for 24 hours and then worked up via the procedure described for hydroamination products. For NMR study of the formation of first turnover products, the reaction was performed inside an NMR tube using C6D6 as solvent, and 4b (0.025 mmol) and thiomorpholine (0.05 mmol) were used in smaller scale, due to disruption of the magnetic field in the presence of a large quantity of nickel complex.

Optimization of Catalytic Reactions: Early experiments revealed that among the four nickel complexes synthesized (4a-d), 4b is more active in hydroamination of allenes with secondary amines. Thus, it was used for further experiments (Table 6).

Table 6. Optimization of catalytic hydroamination.

Catalyst Isolated yield Entry Amine/eq. Time (h) Solvent (mol%) (%) 1 Pyrrolidine/5 48 chloroform 5 -

2 Pyrrolidine/5 48 dioxane 5 -

3 Pyrrolidine/5 48 THF 5 19

4 Pyrrolidine/5 48 benzene 5 45

5 Pyrrolidine/5 48 toluene 5 70

6 Morpholine/4 24 toluene 20 91

7 Morpholine/4 24 toluene 10 73

8 Morpholine/4 24 toluene 5 62

9 Morpholine/4 24 toluene 2.5 57

10 Pyrrolidine/1 48 toluene 5 35

11 Pyrrolidine/2 48 toluene 5 48

12 Pyrrolidine/3 48 toluene 5 53

13 Pyrrolidine/4 48 toluene 5 67

14 Pyrrolidine/5 48 toluene 5 72

Characterization of Complexes, Starting Materials and Hydroamination

Products: Isolated yields for the nickel complexes are reported based on Ni(cod)2.

[(2-Diphenylphosphinocyclopentene-1-(tert-butyl)imine)Ni(allyl)]OTf (4a): Yellow- orange solid (1.85 g, 87% isolated yield) mp: 135-138 oC; 600 MHz 1H NMR: 7.81 (s,

1H), 7.50-7.37 (m, 10H), 5.44 (broad s, 1H), 4.59 (broad s, 1H), 3.48 (broad s, 1H), 2.29-

13 1 2.13 (m, 8H), 1.27 (s, 9H); C{ H} NMR: 164.2 (d, JP-C=7.4 Hz), 155.6 (d, JP-C=15.5

Hz), 134.0 (d, JP-C=31.8 Hz), 132.6 (broad), 129.7 (broad), 127.8 (d, JP-C=47.4 Hz),

31 1 115.4, 64.6, 54.0, 37.7 (d, JP-C=8.7 Hz), 36.6, 30.7, 23.2 (d, JP-C=5.0 Hz); P{ H} NMR:

22.4; 19F NMR: -78.5; IR (neat) 1437 (w), 1385 (w), 1259 (s), 1223 (m), 1183 (w), 1161

(m), 1146 (s), 1102 (m), 1029 (s), 1000 (w), 986 (w), 747 (m). Anal. Calcd. for

C26H31F3NNiO3PS·CH2Cl2 C: 48.46, H; 4.97, N: 2.09; found C: 48.82, H: 5.19, N: 2.23.

[(2-Diphenylphosphinocyclopentene-1-(2,6-dimethylphenyl)imine)Ni(allyl)]OTf

(4b): Orange-brown solid (1.95 g, 85% isolated yield) mp: 92-94 oC; 600 MHz 1H NMR:

7.84 (s, 1H), 7.58 (s, 10H), 7.08 (s, 3H), 5.61-5.58 (m, 1H), 3.20-3.01 (m, 5H), 2.59-2.09

13 1 (m, 11H); C{ H} NMR: 166.7, 155.4, 152.3 (d, JP-C=18.6 Hz), 139.6 (d, JP-C=29.4 Hz),

132.7, 132.2, 130.1 (d, JP-C=10.3 Hz), 129.0, 127.7, 127.2, 118.1, 82.9, 53.4, 38.2, 36.0,

22.5, 19.1; 31P{1H} NMR: 11.9; 19F NMR: -78.6; IR (neat) 1569 (w), 1471 (w), 1436 (w),

1260 (s), 1222 (s), 1145 (s), 1099 (m), 1028 (s), 998 (w), 917 (w), 774 (w), 747 (m), 725

(w). Anal. Calcd. for C30H31F3NNiO3PS·1.2CH2Cl2 C: 51.04, H: 4.59, N: 1.91; found C:

51.02, H: 4.63, N: 1.98.

[(2-Di-tert-butylphosphinocyclopentene-1-(2,6-dimethylphenyl)imine)Ni(allyl)]OTf

(4c): Yellow-orange solid (1.76 g, 82% isolated yield) mp: 85-88 oC; 600 MHz 1H NMR:

7.81 (s, 1H), 7.11-7.09 (m, 3H), 5.50-5.45 (m, 1H), 3.84 (s, 1H), 3.18-3.02 (m, 4H), 2.86-

3 2.81 (m, 2H), 2.28 (s, 3H), 2.09 (s, 3H), 2.05-2.04 (m, 3H), 1.50 (d, JP-H=14.8 Hz, 9H),

3 13 1 1.36 (d, JP-H=14.8 Hz, 9H); C{ H} NMR: 167.4 (d, JP-C=7.1 Hz), 157.1, 152.4 (d, JP-

C=11.9 Hz), 142.1 (d, JP-C=14.3 Hz), 129.2, 128.9, 127.20 (d, JP-C=5.2 Hz), 127.16 (d, JP-

C=7.0 Hz), 117.1, 83.4 (d, JP-C=16.4 Hz), 49.9 (d, JP-C=5.6 Hz), 41.6 (d, JP-C=2.1 Hz), 38.9

(d, JP-C=17.4 Hz), 38.6 (d, JP-C=17.9 Hz), 37.9 (d, JP-C=9.7 Hz), 30.72 (d, JP-C=4.8 Hz),

31 1 19 30.67 (d, JP-C=5.1 Hz), 23.9 (d, JP-C=3.2 Hz), 19.0, 18.9; P{ H} NMR: 50.8; F NMR: -

78.5; IR (neat) 1567 (w), 1526 (w), 1471 (w), 1394 (w), 1370 (w), 1288 (s), 1236 (s),

1223 (s), 1159 (s), 1093 (w), 1027 (s), 935 (w), 806 (w), 772 (m), 724 (w). Anal. Calcd. for C26H39F3NNiO3PS·CH2Cl2 C: 47.88, H; 6.10, N: 2.07; found C: 47.95, H: 6.35, N:

2.09.

[(2-Diphenylphosphinocyclohexene-1-(2,6-dimethylphenyl)imine)Ni(allyl)]OTf (4d):

Brown solid (2.15 g, 91% isolated yield) mp: 110-112 oC; 600 MHz 1H NMR: 7.56-7.43

(m, 11H), 7.05 (s, 3H), 5.52-5.49 (m, 1H), 3.32-2.56 (m, 4H), 2.19-1.70 (m, 14H);

13 1 C{ H} NMR: 170.2 (d, JP-C=12.4 Hz), 155.0, 145.6 (d, JP-C=12.4 Hz), 133.7 (d, JP-

C=28.4 Hz), 132.8 (d, JP-C=11.7 Hz), 131.9, 130.0 (d, JP-C=10.4 Hz), 129.1, 127.8, 127.1,

31 1 117.9, 81.0, 54.1, 33.5 (d, JP-C=10.4 Hz), 29.5, 22.3 (d, JP-C=3.8 Hz), 21.8, 19.0; P{ H}

NMR: 25.4; 19F NMR: -78.5; IR (neat) 1598 (w), 1518 (w), 1436 (w), 1395 (w), 1303

(m), 1261 (s), 1221 (s), 1148 (m), 1098 (w), 1027 (s), 934 (w), 774 (w), 747 (m). Anal.

Calcd. for C31H33F3NNiO3PS·3CH2Cl2 C: 45.32, H: 4.36, N: 1.55; found C: 44.64, H:

4.61, N: 1.52.

Nona-1,2-diene (6b): 600 MHz 1H NMR: 5.09 (quint, 3J=4J=6.6 Hz, 1H), 4.65 (dt, 4J=6.6

Hz, 5J=3.0 Hz, 2H), 2.02-1.97 (m, 2H), 1.43-1.38 (m, 2H), 1.34-1.24 (m, 6H), 0.89 (t,

3J=6.6 Hz, 3H); 13C{1H} NMR: 208.6, 90.3, 74.7, 31.8, 29.3, 28.9, 28.4, 22.8, 14.2.

Hepta-1,2-diene (6c): 400 MHz 1H NMR: 5.09 (quint, 3J=4J=6.8 Hz, 1H), 4.64 (dt,

4J=6.8 Hz, 5J=3.2 Hz, 2H), 2.03-1.96 (m, 2H), 1.42-1.31 (m, 4H), 0.90 (t, 3J=7.2 Hz, 3H);

13C{1H} NMR: 208.6, 90.2, 74.6, 31.4, 28.1, 22.3, 14.0.

N-Allylthiomorpholine (5a): 51% isolated yield (22 mg), 600 MHz 1H NMR: 5.86-5.78

(m, 1H), 5.19-5.13 (m, 2H), 3.00 (dm, 3J=5.4 Hz, 2H), 2.68 (s, 8H); 13C{1H} NMR:

+ 135.1, 118.4, 62.7, 55.0, 28.2; HRMS (ESI) (m/z): [M+H] calc for C7H14NS, 144.0847; found, 144.0840.

N-Allylindoline (5b):244 68% isolated yield (32 mg), 400 MHz 1H NMR: 7.10-7.05 (m,

2H), 6.67 (td, 3J=7.6 Hz, 4J=0.8 Hz, 1H), 6.52 (d, 3J=7.6 Hz, 1H), 5.92 (ddt, 3J=16.4 Hz,

3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.29 (dq, 3J=16.4 Hz, 2J=4J=1.6 Hz, 1H), 5.20 (dq, 3J=10.4

Hz, 2J=4J=1.6 Hz, 1H), 3.72 (dt, 3J=6.0 Hz, 4J=1.6 Hz, 2H), 3.34 (t, 3J=8.4 Hz, 2H), 2.97

(t, 3J=8.4 Hz, 2H); 13C{1H} NMR: 152.3, 134.3, 130.4, 127.4, 124.6, 117.8, 117.4, 107.5,

+ 53.3, 52.3, 28.7; HRMS (ESI) (m/z): [M+H] calc for C11H14N, 160.1126; found,

160.1118.

(E)-1-(3-Cyclohexylallyl)pyrrolidine (7a):245 (E:Z 1.00:0.02 by 1H NMR) 67% isolated yield (65 mg), 600 MHz 1H NMR: 5.54 (dd, 3J=15.6 Hz, 3J=6.0 Hz, 1H), 5.49 (dt,

3J=15.6 Hz, 3J=6.0 Hz, 1H), 3.01 (d, 3J=6.0 Hz, 2H), 2.48-2.46 (m, 4H), 1.96-1.91 (m,

1H), 1.78-1.75 (m, 4H), 1.71-1.68 (m, 4H), 1.65-1.60 (m, 1H), 1.28-1.21 (m, 2H), 1.17-

1.02 (m, 3H); 13C{1H} NMR: 139.4, 125.0, 58.6, 54.0, 40.6, 33.1, 26.3, 26.2, 23.5;

+ HRMS (ESI) (m/z): [M+H] calc for C13H24N, 194.1909; found, 194.1913.

(E)-1-(3-Cyclohexylallyl)piperidine (7b):246 (E:Z 1.00:0.05 by 1H NMR) 52% isolated yield (54 mg), 600 MHz 1H NMR: 5.49 (dd, 3J=15.6 Hz, 3J=6.0 Hz, 1H), 5.43 (dt,

3J=15.6 Hz, 3J=6.6 Hz, 1H), 2.87 (d, 3J=6.6 Hz, 2H), 2.33 (broad s, 4H), 1.95-1.90 (m,

1H), 1.71-1.67 (m, 4H), 1.64-1.60 (m, 1H), 1.56 (quint, 3J=6.0 Hz, 4H), 1.41 (broad s,

2H), 1.28-1.20 (m, 2H), 1.16-1.01 (m, 3H); 13C{1H} NMR: 140.3, 124.1, 62.1, 54.5, 40.6,

+ 33.1, 26.3, 26.2, 26.1, 24.6; HRMS (ESI) (m/z): [M+H] calc for C14H26N, 208.2065; found, 208.2060.

(E)-4-(3-Cyclohexylallyl)morpholine (7c):206 (E:Z 1.00:0.07 by 1H NMR) 71% isolated yield (74 mg) 400 MHz 1H NMR: 5.55 (dd, 3J=15.2 Hz, 3J=6.4 Hz, 1H), 5.40 (dt, 3J=15.2

Hz, 3J= 6.8 Hz, 1H), 3.71 (t, 3J=4.4 Hz, 4H), 2.92 (d, 3J=6.8 Hz, 2H), 2.42 (s, 4H), 1.96-

1.91 (m, 1H), 1.71-1.61 (m, 5H), 1.30-1.00 (m, 5H); 13C{1H} NMR: 141.3, 123.1, 67.1,

+ 61.6, 53.6, 40.6, 33.0, 26.3, 26.1; HRMS (ESI) (m/z): [M+H] calc for C13H24NO,

210.1858; found, 210.1853.

(E)-4-(3-Cyclohexylallyl)thiomorpholine (7d): (E:Z 1.00:0.02 by 1H NMR) 91% isolated yield (103 mg), 600 MHz 1H NMR: 5.52 (dd, 3J=15.6 Hz, 3J=6.6 Hz, 1H), 5.38

(dtd, 3J=15.6 Hz, 3J=6.6 Hz, 4J=1.2 Hz, 1H), 2.93 (d, 3J=6.6 Hz, 2H), 2.67 (s, 8H), 1.96-

1.91 (m, 1H), 1.69 (d, 3J=10.8 Hz, 4H), 1.65-1.61 (m, 1H), 1.28-1.21 (m, 2H), 1.17-1.01

(m, 3H); 13C{1H} NMR: 141.1, 123.3, 62.0, 54.9, 40.6, 33.0, 28.1, 26.3, 26.1; HRMS

+ (ESI) (m/z): [M+H] calc for C13H24NS, 226.1629; found, 226.1625.

(2S,6R)-4-((E)-3-Cyclohexylallyl)-2,6-dimethylmorpholine (7e): (E:Z 1.00:0.15 by 1H

NMR) 87% isolated yield (103 mg), 600 MHz 1H NMR: 5.52 (dd, 3J=15.6 Hz, 3J=6.6

Hz, 1H), 5.39 (dtd, 3J=15.6 Hz, 3J=7.2 Hz, 4J=1.2 Hz, 1H), 3.68-3.63 (m, 2H), 2.88 (d,

3J=7.2 Hz, 2H), 2.72 (d, 3J=10.2 Hz, 2H), 1.96-1.91 (m, 1H), 1.71-1.61 (m, 7H), 1.27-

1.20 (m, 2H), 1.16-1.02 (m, 9H); 13C{1H} NMR: 141.0, 123.2, 71.8, 61.2, 59.5, 40.6,

+ 33.0, 26.3, 26.1, 19.3; HRMS (ESI) (m/z): [M+H] calc for C15H28NO, 238.2171; found,

238.2161.

(E)-1-(3-Cyclohexylallyl)-4-methylpiperazine (7f): 50% isolated yield (56 mg), 600

MHz 1H NMR: 5.54 (dd, 3J=15.2 Hz, 3J=6.4 Hz, 1H), 5.42 (dm, 3J=15.2 Hz, 1H), 2.93 (d,

3J=6.8 Hz, 2H), 2.70-2.20 (broad s, 8H), 2.28 (s, 3H), 1.97-1.90 (m, 1H), 1.73-1.60 (m,

5H), 1.31-1.01 (m, 5H); 13C{1H} NMR: 140.9, 123.6, 61.2, 55.3, 53.1, 46.2, 40.6, 33.0,

+ 26.3, 26.2; HRMS (ESI) (m/z): [M+H] calc for C14H27N2, 223.2174; found, 223.2171.

(E)-1-Benzhydryl-4-(3-cyclohexylallyl)piperazine (7g): 39% isolated yield (73 mg),

600 MHz 1H NMR: 7.40 (d, 3J=7.2 Hz, 4H), 7.23 (t, 3J=7.2 Hz, 4H), 7.13 (t, 3J=7.2 Hz,

2H), 5.51 (dd, 3J=15.6 Hz, 3J=6.6 Hz, 1H), 5.42 (dtd, 3J=15.6 Hz, 3J=6.6 Hz, 4J=1.2 Hz,

1H), 4.21 (s, 1H), 2.92 (d, 3J=6.6 Hz, 2H), 2.44 (broad s, 8H), 1.95-1.89 (m, 1H), 1.68 (d,

3J=10.8 Hz, 4H), 1.62-1.59 (m, 1H), 1.26-1.01 (m, 5H); 13C{1H} NMR: 142.8, 140.6,

128.5, 128.0, 126.9, 123.6, 76.3, 61.1, 53.3, 51.9, 40.5, 33.0, 26.2, 26.1; HRMS (ESI)

+ (m/z): [M+H] calc for C26H35N2, 375.2800; found, 375.2784.

(E)-1-(3-Cyclohexylallyl)indoline (7h): (E:Z 1.00:0.14 by 1H NMR) 92% isolated yield

(111 mg), 600 MHz 1H NMR: 7.08-7.04 (m, 2H), 6.65 (t, 3J=6.0 Hz, 1H), 6.53 (d, 3J=6.0

Hz, 1H), 5.64 (dd, 3J=15.6 Hz, 3J=6.6 Hz, 1H), 5.47 (dtd, 3J=15.6 Hz, 3J=6.6 Hz, 3J=1.2

Hz, 1H), 3.65 (d, 3J=6.6 Hz, 2H), 3.30 (t, 3J=7.8 Hz, 2H), 2.94 (t, 3J=7.8 Hz, 2H), 1.99-

1.94 (m, 1H), 1.71 (d, 3J=10.8 Hz, 4H), 1.66-1.63 (m, 1H), 1.30-1.23 (m, 2H), 1.19-1.05

(m, 3H); 13C{1H} NMR: 152.4, 140.3, 130.6, 127.3, 124.5, 122.9, 117.7, 107.6, 53.1,

+ 51.7, 40.6, 33.1, 28.6, 26.3, 26.1; HRMS (ESI) (m/z): [M+H] calc for C17H24N,

242.1909; found, 242.1908.

(E)-1-(3-Cyclohexylallyl)-2-methylindoline (7i): 53% isolated yield (68 mg), 600 MHz

1H NMR: 7.04-7.01 (m, 2H), 6.61 (t, 3J=7.4 Hz, 1H), 6.46 (d, 3J=7.4 Hz, 1H), 5.62 (dd,

3J=15.5 Hz, 3J=6.7 Hz, 1H), 5.41 (dm, 3J=15.5 Hz, 1H), 3.79 (dd, 2J=15.5 Hz, 3J=4.8 Hz,

1H), 3.70-3.64 (m, 1H), 3.58 (dd, 2J=15.5 Hz, 3J=7.4 Hz, 1H), 3.09 (dd, 2J=15.4 Hz,

3J=8.5 Hz, 1H), 2.59 (dd, 2J=15.4 Hz, 3J=9.9 Hz, 1H), 1.97-1.89 (m, 1H), 1.72-1.67 (m,

4H), 1.66-1.60 (m, 1H), 1.31-1.02 (m, 8H); 13C{1H} NMR: 152.5, 139.7, 129.2, 127.4,

124.2, 122.9, 117.3, 107.2, 59.5, 48.6, 40.6, 37.4, 33.1, 33.0, 26.3, 26.1, 19.4; HRMS

+ (ESI) (m/z): [M+H] calc for C18H26N, 256.2065; found, 256.2054.

(E)-2-(3-Cyclohexylallyl)-1,2,3,4-tetrahydroisoquinoline (7j):246 (E:Z 1.00:0.02 by 1H

NMR) 84% isolated yield (107 mg), 400 MHz 1H NMR: 7.14-7.08 (m, 3H), 7.03-7.01

(m, 1H), 5.63 (dd, 3J=15.6 Hz, 3J=6.0 Hz, 1H), 5.53 (dt, 3J=15.6 Hz, 3J=6.4 Hz, 1H), 3.61

(s, 2H), 3.12 (d, 3J=6.4 Hz, 2H), 2.92 (t, 3J=6.0 Hz, 2H), 2.73 (t, 3J=6.0 Hz, 2H), 2.04-

1.97 (m, 1H), 1.78-1.72 (m, 4H), 1.69-1.64 (m, 1H), 1.34-1.07 (m, 5H); 13C{1H} NMR:

140.7, 135.0, 134.4, 128.7, 126.7, 126.1, 125.6, 123.9, 60.9, 56.1, 50.6, 40.6, 33.1, 29.2,

+ 26.3, 26.2; HRMS (ESI) (m/z): [M+H] calc for C18H26N, 256.2065; found, 256.2048.

(E)-1-(Non-2-en-1-yl)pyrrolidine (8a):245 63% isolated yield (62 mg) 400 MHz 1H

NMR: 5.62-5.49 (m, 2H), 3.02 (d, 3J=5.6 Hz, 2H), 2.49-2.45 (m, 4H), 2.01 (q, 3J=7.2 Hz,

2H), 1.79-1.75 (m, 4H), 1.37-1.25 (m, 8H), 0.87 (t, 3J=6.8 Hz, 3H); 13C{1H} NMR:

133.6, 127.6, 58.5, 54.1, 32.5, 31.9, 29.4, 29.0, 23.5, 22.8, 14.2; HRMS (ESI) (m/z):

+ [M+H] calc for C13H26N, 196.2065; found, 196.2062.

(E)-4-(Non-2-en-1-yl)morpholine (8b): (E:Z 1.00:0.07 by 1H NMR) 82% isolated yield

(87 mg), 600 MHz 1H NMR: 5.58 (dt, 3J=15.3 Hz, 3J=6.8 Hz, 1H), 5.44 (dtt, 3J=15.3 Hz,

3J=6.8 Hz, 4J=1.3 Hz, 1H), 3.70 (t, 3J=4.6 Hz, 4H), 2.91 (dd, 3J=6.8 Hz, 4J=0.8 Hz, 2H),

2.41 (s, 4H), 2.00 (q, 3J=6.8 Hz, 2H), 1.36-1.32 (m, 2H), 1.30-1.21 (m, 6H), 0.86 (t,

3J=7.1 Hz, 3H); 13C{1H} NMR: 135.4, 125.7, 67.1, 61.5, 53.6, 32.5, 31.8, 29.3, 29.0,

+ 22.7, 14.2; HRMS (ESI) (m/z): [M+H] calc for C13H26NO, 212.2014; found, 212.2007.

(E)-4-(Non-2-en-1-yl)thiomorpholine (8c): (E:Z 1.00:0.24 by 1H NMR) 93% isolated yield (106 mg), 600 MHz 1H NMR 5.57 (dt, 3J=15.0 Hz, 3J=7.2 Hz, 1H), 5.43 (dt,

3J=15.0 Hz, 3J=6.6 Hz, 1H), 2.94 (d, 3J=6.6 Hz, 2H), 2.68 (s, 8H), 2.02 (q, 3J=7.2 Hz,

2H), 1.36-1.23 (m, 8H), 0.87 (t, 3J=7.2 Hz, 3H); 13C{1H} NMR: 135.3, 125.9, 61.9, 54.9,

+ 32.5, 31.8, 29.3, 29.0, 28.1, 22.8, 14.2; HRMS (ESI) (m/z): [M+H] calc for C13H26NS,

228.1786; found, 228.1785.

(2S,6R)-2,6-Dimethyl-4-((E)-non-2-en-1-yl)morpholine (8d): 90% isolated yield (108 mg), 400 MHz 1H NMR: 5.58 (dt, 3J=15.2 Hz, 3J=6.8 Hz, 1H), 5.45 (dm, 3J=15.2 Hz,

1H), 3.71-3.64 (m, 2H), 2.89 (d, 3J=6.4 Hz, 2H), 2.75 (d, 3J=10.4 Hz, 2H), 2.02 (q, 3J=6.8

Hz, 2H), 1.65 (t, 3J=10.4 Hz, 2H), 1.37-1.26 (m, 8H), 1.15 (d, 3J=6.0 Hz, 6H), 0.87 (t,

3J=7.2 Hz, 3H); 13C{1H} NMR: 135.3, 125.9, 71.8, 61.1, 59.5, 32.5, 31.8, 29.3, 29.0,

+ 22.8, 19.4, 14.2; HRMS (ESI) (m/z): [M+H] calc for C15H30NO, 240.2327; found,

240.2313.

(E)-1-(Non-2-en-1-yl)indoline (8e): (E:Z 1.00:0.08 by 1H NMR) 80% isolated yield (97 mg), 600 MHz 1H NMR: 7.10-7.05 (m, 2H), 6.63 (t, 3J=7.3 Hz, 1H), 6.52 (d, 3J=7.3 Hz,

1H), 5.69 (dt, 3J=15.2 Hz, 3J=6.8 Hz, 1H), 5.52 (dm, 3J=15.2 Hz, 1H), 3.66 (d, 3J=6.3 Hz,

2H), 3.31 (t, 3J=8.2 Hz, 2H), 2.94 (t, 3J=8.2 Hz, 2H), 2.04 (q, 3J=6.8 Hz, 2H), 1.40-1.25

(m, 8H), 0.89 (t, 3J=6.8 Hz, 3H); 13C{1H} NMR: 152.4, 134.4, 130.5, 127.3, 125.4, 124.5,

117.7, 107.6, 53.1, 51.5, 32.5, 31.8, 29.4, 29.0, 28.6, 22.8, 14.2; HRMS (ESI) (m/z):

+ [M+H] calc for C17H26N, 244.2065; found, 244.2062.

(E)-2-(Non-2-en-1-yl)-1,2,3,4-tetrahydroisoquinoline (8f): (E:Z 1.00:0.13 by 1H NMR)

91% isolated yield (117 mg), 600 MHz 1H NMR: 7.13-7.08 (m, 3H), 7.03-7.01 (m, 1H),

5.66 (dt, 3J=15.6 Hz, 3J=6.6 Hz, 1H), 5.57 (dt, 3J=15.6 Hz, 3J=6.6 Hz, 1H), 3.61 (s, 2H),

3.12 (d, 3J=6.6 Hz, 2H), 2.91 (t, 3J=6.0 Hz, 2H), 2.73 (t, 3J=6.0 Hz, 2H), 2.07 (q, 3J=6.6

Hz, 2H), 1.40 (quint, 3J=6.6 Hz, 2H), 1.34-1.26 (m, 6H), 0.90 (t, 3J=6.6 Hz, 3H);

13C{1H} NMR: 135.0, 134.9, 134.5, 128.8, 126.7, 126.6, 126.2, 125.6, 60.9, 56.1, 50.6,

+ 32.5, 31.8, 29.3, 29.2, 29.0, 22.8, 14.3; HRMS (ESI) (m/z): [M+H] calc for C18H28N,

258.2222; found, 258.2213.

(E)-1-(Hept-2-en-1-yl)pyrrolidine (9a):247 (E:Z 1.00:0.06 by 1H NMR) 75% isolated yield (63 mg), 400 MHz 1H NMR: 5.62-5.49 (m, 2H), 5.02 (d, 3J=5.2 Hz, 2H), 2.49-2.46

(m, 4H), 2.01 (q, 3J=6.8 Hz, 2H), 1.79-1.74 (m, 4H), 1.38-1.27 (m, 4H), 0.88 (t, 3J=7.2

Hz, 3H); 13C{1H} NMR: 133.5, 127.6, 58.5, 54.1, 32.2, 31.5, 23.5, 22.3, 14.1; HRMS

+ (ESI) (m/z): [M+H] calc for C11H22N, 168.1752; found, 168.1746.

(E)-4-(Hept-2-en-1-yl)morpholine (9b):247 (E:Z 1.00:0.18 by 1H NMR) 60% isolated yield (55 mg), 600 MHz 1H NMR: 5.60 (dt, 3J=15.2 Hz, 3J=6.8 Hz, 1H), 5.46 (dt,

3J=15.2 Hz, 3J=6.4 Hz, 1H), 3.72 (t, 3J=4.8 Hz, 4H), 2.93 (d, 3J=6.4 Hz, 2H), 2.43 (broad

s, 4H), 2.03 (q, 3J=6.8 Hz, 2H), 1.38-1.28 (m, 4H), 0.89 (t, 3J=7.2 Hz, 3H); 13C{1H}

NMR: 135.4, 125.8, 67.1, 61.5, 53.7, 32.2, 31.5, 22.4, 14.1; HRMS (ESI) (m/z): [M+H]+ calc for C11H22NO, 184.1701; found, 184.1692.

(E)-4-(Hept-2-en-1-yl)thiomorpholine (9c): (E:Z 1.00:0.25 by 1H NMR) 82% isolated yield (82 mg), 600 MHz 1H NMR: 5.57 (dm, 3J=15.2 Hz, 1H), 5.42 (dm, 3J=15.2 Hz,

1H), 2.95 (d, 3J=6.8 Hz, 2H), 2.68 (s, 8H), 2.02 (q, 3J=6.8 Hz, 2H), 1.36-1.28 (m, 4H),

0.88 (t, 3J=7.2 Hz, 3H); 13C{1H} NMR: 135.3, 125.9, 61.9, 54.9, 32.2, 31.5, 28.1, 22.4,

+ 14.1; HRMS (ESI) (m/z): [M+H] calc for C11H22NS, 200.1473; found, 200.1464.

(2S,6R)-4-((E)-Hept-2-en-1-yl)-2,6-dimethylmorpholine (9d): (E:Z 1.00:0.34 by 1H

NMR) 79% isolated yield (83 mg), 600 MHz 1H NMR: 5.62-5.55 (m, 1H), 5.48-5.43 (m,

1H), 3.70-3.66 (m, 2H), 2.91 (d, 3J=6.2 Hz, 2H), 2.76 (t, 3J=10.6 Hz, 2H), 2.06-2.01 (m,

2H), 1.70-1.65 (m, 2H), 1.37-1.29 (m, 4H), 1.16 (d, 3J=6.3 Hz, 6H), 0.89 (t, 3J=7.2 Hz,

3H); 13C{1H} NMR: 135.4, 125.8, 71.8, 61.1, 59.5, 37.2, 31.5, 22.4, 19.4, 14.1; HRMS

+ (ESI) (m/z): [M+H] calc for C13H26NO, 212.2014; found, 212.2008.

(E)-1-(Hept-2-en-1-yl)indoline (9e): (E:Z 1.00:0.09 by 1H NMR) 76% isolated yield (82 mg), 600 MHz 1H NMR: 7.08-7.04 (m, 2H), 6.65 (t, 3J=7.3 Hz, 1H), 6.52 (d, 3J=7.3 Hz,

1H), 5.69 (dt, 3J=15.2 Hz, 3J=6.8 Hz, 1H), 5.52 (dm, 3J=15.2 Hz, 1H), 3.65 (d, 3J=6.4 Hz,

2H), 3.31 (t, 3J=8.3 Hz, 2H), 2.94 (t, 3J=8.3 Hz, 2H), 2.04 (q, 3J=6.8 Hz, 2H), 1.38-1.30

(m, 4H), 0.90 (t, 3J=7.2 Hz, 3H); 13C{1H} NMR: 152.4, 134.4, 130.5, 127.3, 125.5, 124.5,

117.7, 107.6, 53.1, 51.5, 32.1, 31.6, 28.6, 22.4, 14.8; HRMS (ESI) (m/z): [M+H]+ calc for

C15H22N, 216.1752; found, 216.1750.

(E)-2-(Hept-2-en-1-yl)-1,2,3,4-tetrahydroisoquinoline (9f): (E:Z 1.00:0.08 by 1H

NMR) 79% isolated yield (91 mg), 600 MHz 1H NMR: 7.12-7.07 (m, 3H), 7.02-7.00 (m,

1H), 5.66 (dt, 3J=15.3 Hz, 3J=6.5 Hz, 1H), 5.57 (dm, 3J=15.3 Hz, 1H), 3.61 (s, 2H), 3.12

(d, 3J=6.6 Hz, 2H), 2.91 (t, 3J=5.8 Hz, 2H), 2.73 (t, 3J=5.8 Hz, 2H), 2.07 (q, 3J=6.5 Hz,

2H), 1.41-1.32 (m, 4H), 0.90 (t, 3J=7.0 Hz, 3H); 13C{1H} NMR: 135.0, 134.9, 134.4,

128.8, 126.7, 126.5, 126.2, 125.6, 60.8, 56.1, 50.6, 32.2, 31.5, 29.2, 22.4, 14.1; HRMS

+ (ESI) (m/z): [M+H] calc for C16H24N, 230.1909; found, 230.1908.

(E)-1-(4-Phenylbut-2-en-1-yl)pyrrolidine (10a): (E:Z 1.00:0.07 by 1H NMR) 91% isolated yield (92 mg), 400 MHz 1H NMR: 7.31-7.27 (m, 2H), 7.21-7.17 (m, 3H), 5.76

(dt, 3J=15.2 Hz, 3J=6.4 Hz, 1H), 5.65 (dtt, 3J=15.2 Hz, 3J=6.4 Hz, 4J=1.2 Hz, 1H), 3.37 (d,

3J=6.4 Hz, 2H), 3.07 (d, 3J=6.4 Hz, 2H), 2.51-2.47 (m, 4H), 1.80-1.76 (m, 4H); 13C{1H}

NMR: 140.6, 131.7, 129.4, 128.7, 128.5, 126.1, 58.3, 54.1, 39.0, 23.5; HRMS (ESI)

+ (m/z): [M+H] calc for C14H20N, 202.1596; found, 202.1588.

(E)-4-(4-Phenylbut-2-en-1-yl)morpholine (10b):206 (E:Z 1.00:0.21 by 1H NMR) 83% isolated yield (90 mg), 400 MHz 1H NMR: 7.31-7.27 (m, 2H), 7.22-7.16 (m, 3H), 5.78

(dm, 3J=15.2 Hz, 1H), 5.56 (dm, 3J=15.2 Hz, 1H), 3.72 (t, 3J=4.8 Hz, 4H), 3.38 (d, 3J=6.8

Hz, 2H), 2.98 (d, 3J=6.8 Hz, 2H), 2.44 (broad s, 4H); 13C{1H} NMR: 140.3, 133.6,

128.63, 128.56, 127.5, 126.2, 67.1, 61.3, 53.7, 39.0; HRMS (ESI) (m/z): [M+H]+ calc for

C14H20NO, 218.1545; found, 218.1541.

(E)-4-(4-Phenylbut-2-en-1-yl)thiomorpholine (10c): (E:Z 1.00:0.22 by 1H NMR) 81% isolated yield (95 mg), 600 MHz 1H NMR: 7.31-7.27 (m, 2H), 7.21-7.17 (m, 3H), 5.75

(dtm, 3J=15.2 Hz, 3J=6.4 Hz, 1H), 5.54 (dtm, 3J=15.2 Hz, 3J=6.4 Hz, 1H), 3.38 (d, 3J=6.4

Hz, 2H), 3.00 (dd, 3J=6.4 Hz, 4J=1.0 Hz, 2H), 2.69 (s, 8H); 13C{1H} NMR: 140.2, 133.3,

128.52, 128.47, 128.3, 126.1, 61.5, 54.8, 38.9, 28.9; HRMS (ESI) (m/z): [M+H]+ calc for

C14H20NS, 234.1316; found, 234.1315.

(2S,6R)-2,6-Dimethyl-4-((E)-4-phenylbut-2-en-1-yl)morpholine (10d): (E:Z 1.00:0.28 by 1H NMR) 81% isolated yield (99 mg), 600 MHz 1H NMR: 7.30-7.27 (m, 2H), 7.21-

7.17 (m, 3H), 5.76 (dtm, 3J=15.2 Hz, 3J=6.8 Hz, 1H), 5.57 (dtm, 3J=15.2 Hz, 3J=6.8 Hz,

1H), 3.71-3.66 (m, 2H), 3.38 (d, 3J=6.8 Hz, 2H), 2.95 (dd, 3J=6.8 Hz, 4J=0.8 Hz, 2H),

2.75 (d, 3J=11.4 Hz, 2H), 1.68 (t, 3J=11.4 Hz, 2H), 1.16 (d, 3J=6.6 Hz, 6H); 13C{1H}

NMR: 140.3, 133.4, 128.6, 128.5, 128.4, 126.2, 71.8, 60.8, 59.5, 39.0, 19.3; HRMS (ESI)

+ (m/z): [M+H] calc for C16H24NO, 246.1858; found, 246.1850.

(E)-1-(4-Phenylbut-2-en-1-yl)indoline (10e): 79% isolated yield (98 mg), 400 MHz 1H

NMR: 7.30 (t, 3J=7.2 Hz, 2H), 7.23-7.18 (m, 3H), 7.09-7.04 (m, 2H), 6.66 (t, 3J=7.6 Hz,

1H), 6.52 (d, 3J=7.6 Hz, 1H), 5.86 (dtt, 3J=15.2 Hz, 3J=6.8 Hz, 4J=1.2 Hz, 1H), 5.64 (dtt,

3J=15.2 Hz, 3J=6.4 Hz, 4J=1.2 Hz, 1H), 3.70 (dd, 3J=6.4 Hz, 4J=1.2 Hz, 2H), 3.40 (d,

3J=6.8 Hz, 2H), 3.33 (t, 3J=8.4 Hz, 2H), 2.95 (t, 3J=8.4 Hz, 2H); 13C{1H} NMR: 152.3,

140.4, 132.6, 130.5, 128.7, 128.6, 127.4, 127.3, 126.2, 124.6, 117.8, 107.6, 53.3, 51.3,

+ 38.9, 28.6; HRMS (ESI) (m/z): [M+H] calc for C18H20N, 250.1596; found, 250.1589.

(E)-2-(4-Phenylbut-2-en-1-yl)-1,2,3,4-tetrahydroisoquinoline (10f): (E:Z 1.00:0.31 by

1H NMR) 77% isolated yield (101 mg), 600 MHz 1H NMR: 7.32-7.29 (m, 2H), 7.22-7.21

(m, 3H), 7.13-7.09 (m, 3H), 7.01 (d, 3J=6.2 Hz, 1H), 5.84 (dt, 3J=15.2 Hz, 3J=6.8 Hz,

1H), 5.68 (dt, 3J=15.2 Hz, 3J=6.8 Hz, 1H), 3.63 (s, 2H), 3.42 (d, 3J=6.8 Hz, 2H), 3.17 (d,

3J=6.8 Hz, 2H), 2.92 (t, 3J=5.9 Hz, 2H), 2.75 (t, 3J=5.9 Hz, 2H); 13C{1H} NMR: 140.3,

133.1, 128.7, 128.6, 128.52, 128.46, 128.3, 128.0, 126.6, 126.14, 126.08, 125.6, 60.4,

+ 56.0, 50.6, 38.9, 29.1; HRMS (ESI) (m/z): [M+H] calc for C19H22N, 264.1752; found,

264.1744.

1-(3-Methylbut-2-en-1-yl)pyrrolidine (11a):182 63% isolated yield (44 mg), 600 MHz

1H NMR: 5.31 (tm, 3J=7.2 Hz, 1H), 3.06 (d, 3J=7.2 Hz, 2H), 2.51-2.48 (m, 4H), 1.78-1.76

(m, 4H), 1.72 (s, 3H), 1.65 (s, 3H); 13C{1H} NMR: 134.0, 122.3, 54.2, 53.6, 26.0, 23.6,

+ 18.1; HRMS (ESI) (m/z): [M+H] calc for C9H18N, 140.1439; found, 140.1435.

4-(3-Methylbut-2-en-1-yl)morpholine (11b):244 83% isolated yield (64 mg), 600 MHz

1H NMR: 5.21 (tsept, 3J=7.2 Hz, 4J=1.2 Hz, 1H), 3.69 (t, 3J=4.2 Hz, 4H), 2.92 (d, 3J=7.2

Hz, 2H), 2.41 (s, 4H), 1.71 (d, 4J=1.2 Hz, 3H), 1.62 (d, 4J=1.2 Hz, 3H); 13C{1H} NMR:

+ 135.9, 120.5, 67.1, 56.6, 53.7, 26.0, 18.1; HRMS (ESI) (m/z): [M+H] calc for C9H18NO,

156.1388; found, 156.1383.

4-(3-Methylbut-2-en-1-yl)thiomorpholine (11c):182 80% isolated yield (69 mg), 600

MHz 1H NMR: 5.19 (tsept, 3J=7.2 Hz, 4J=1.2 Hz, 1H), 2.93 (d, 3J=7.2 Hz, 2H), 2.66 (s,

8H), 1.70 (d, 4J=1.2 Hz, 3H), 1.61 (d, 4J=1.2 Hz, 3H); 13C{1H} NMR: 135.8, 120.7, 57.0,

+ 55.0, 28.2, 26.0, 18.1; HRMS (ESI) (m/z): [M+H] calc for C9H18NS, 172.1160; found,

172.1162.

(2S,6R)-2,6-Dimethyl-4-(3-methylbut-2-en-1-yl)morpholine (11d): 90% isolated yield

(82 mg), 600 MHz 1H NMR: 5.20 (tm, 3J=7.2 Hz, 1H), 3.64 (m, 2H), 2.88 (d, 3J=7.2 Hz,

2H), 2.71 (d, 3J=10.2 Hz, 2H), 1.69 (s, 3H), 1.64 (t, 3J=10.2 Hz, 2H), 1.60 (s, 3H), 1.11

(d, 3J=6.6 Hz, 6H); 13C{1H} NMR: 135.7, 120.7, 71.8, 59.6, 56.2, 26.1, 19.4, 18.2;

+ HRMS (ESI) (m/z): [M+H] calc for C11H22NO, 184.1701; found, 184.1695.

1-(3-Methylbut-2-en-1-yl)indoline (11e):244 68% isolated yield (64 mg), 600 MHz 1H

NMR: 7.09-7.05 (m, 2H), 6.66 (t, 3J=7.2 Hz, 1H), 6.53 (d, 3J=7.2 Hz, 1H), 5.31 (tm,

3J=7.8 Hz, 1H), 3.70 (d, 3J=7.8 Hz, 2H), 3.31 (t, 3J=8.4 Hz, 2H), 2.93 (t, 3J=8.4 Hz, 2H),

1.75 (d, 4J=1.2 Hz, 3H), 1.72 (s, 3H); 13C{1H} NMR: 152.6, 135.5, 130.6, 127.3, 124.5,

120.2, 117.7, 107.6, 53.2, 46.8, 28.7, 25.9, 18.2; HRMS (ESI) (m/z): [M+H]+ calc for

C13H18N, 188.1439; found, 188.1436.

2-(3-Methylbut-2-en-1-yl)-1,2,3,4-tetrahydroisoquinoline (11f):206 78% isolated yield

(79 mg), 600 MHz 1H NMR: 7.13-7.08 (m, 3H), 7.03-7.01 (m, 1H), 5.35 (tm, 3J=7.2 Hz,

1H), 3.62 (s, 2H), 3.13 (d, 3J=7.2 Hz, 2H), 2.91 (t, 3J=5.4 Hz, 2H), 2.73 (t, 3J=5.4 Hz,

2H), 1.77 (d, 4J=1.2 Hz, 3H), 1.70 (s, 3H); 13C{1H} NMR: 135.5, 135.1, 134.5, 128.8,

126.7, 126.2, 125.6, 121.3, 56.2, 56.0, 50.8, 29.3, 26.1, 18.3; HRMS (ESI) (m/z): [M+H]+ calc for C14H20N, 202.1596; found, 202.1595.

Crystallography: A summary of crystal data and collection parameters for crystal structure of 4b is provided in Table 7. Detailed descriptions of data collection, as well as data solution, are provided below. A suitable crystal was mounted on a polymer loop using Paratone-N hydrocarbon oil. The crystal was transferred to a Apex2 diffractometer with a CCD area detector, centered in the X-ray beam, and cooled to 150 K using a nitrogen-flow low-temperature apparatus that had been previously calibrated by a thermocouple placed at the same position as the crystal. An arbitrary hemisphere of data was collected using 0.3o ω scans, and the data were integrated by the program SAINT.

The final unit cell parameters were determined by a least-squares refinement of the reflections with I > 2σ(I). Data analysis using Siemens XPREP and the successful solution and refinement of the structure determined the space group. Equivalent reflections were averaged, and the structure was solved by direct methods using the

SHELXTL software package. All non-hydrogen atoms were refined anisotropically. X-

ray quality crystals of 4b were grown from a pentane layered tetrahydrofuran solution at room temperature.

Table 7. Crystallographic data for compound 4b.

Compound 4b Formula C30H31F3NNiO3PS·C4H8O Formula weight 704.41 Space group P21/n Crystal system Monoclinic Temperature (K) 150 a (Å) 14.349(3) b (Å) 13.574(3) c (Å) 16.910(4) α (o) 90.00 β (o) 91.132(3) γ (o) 90.00 V (Å3) 3292.8(12) Z 5 3 Densitycalc (g/cm ) 1.594 Diffractometer Bruker APEX2 Radiation Mo-Kα (λ = 0.71073 Å) Monochromator Graphite Detector CCD detector Scan type, width Ω, 0.3o Scan speed (s) 10 Reflections measured Hemisphere 2θ range (o) 3.68-65.52 Crystal dimensions (mm) 0.26 x 0.23 x 0.14 Reflections measured 57925 Unique reflections 11849 Observations (I > 2σ(I)) 9005 Rint 0.0429 Parameters 433 Robs, Rw, Rall 0.0480, 0.1391, 0.0675 GoF 1.055

3.4 Conclusion

In summary, we have described the synthesis of novel cationic [(3IP)Ni(allyl)]+ complexes and their reactivity in the hydroamination of allenes with secondary amines, constituting the first example of nickel-catalyzed hydroamination of unactivated substrates. The resulting allylamines were isolated in good yields and characterized by

NMR spectroscopy and mass spectrometry. These results revealed good efficiency and selectivity with these new nickel complexes, although we expect that higher reactivity can be achieved by further tuning the ligand system. Further study of the mechanism and continued expansion of the hydroamination substrate scope utilizing these novel nickel catalysts is ongoing.

Chapter 4

Efficient Regioselective Allene Hydrosilylation Catalyzed by a [(3- Iminophosphine)Pd(allyl)]OTf Precatalyst

4.1 Introduction

The catalytic hydrosilylation of C-C unsaturated bonds has garnered great interest in recent years since the resulting products can be further utilized in a wide variety of subsequent reactions.132 For example, allyl and vinylsilanes are indispensable organosilicon reagents due to their direct transformation into vinyl and allylalcohols and use as coupling partners in Hiyama and Sakurai reactions.248-251 Catalytic hydrosilylation is one of the most economic routes to organosilicon compounds, especially when compared to traditional synthetic methods requiring stoichiometric amounts of organometallic chemicals and other reagents.252-257 Although four decades of hydrosilylation studies with various catalysts have provided remarkable knowledge on Si-

H bond addition to unsaturated C-C frameworks, research on the mechanism of this catalytic addition remains an area of active study.132, 258-266 A recent DFT investigation has helped to confirm the mechanism of allene hydrosilylation catalyzed by NHC- supported Ni(0) and Pd(0), a hydrosilylation system displaying intriguing regiochemical outcomes.266 With a focus on expanding the substrate scope in the past few years, the 87

catalytic hydrosilylation of conjugated 1,3-dienes has proven to be both interesting and challenging because of the regioselectivity issues that arise for unsymmetrical substrates,267-272 ultimately leading to the formation of various allyl- and vinylsilane isomers. Although catalytic hydrosilylation of 1,3-dienes has been well studied,267, 269 few examples of catalytic allene hydrosilylation have been reported, limited to only a very small set of substrates.271, 273, 274

An elegant recent example of allene hydrosilylation was reported by Montgomery et al. in which N-heterocyclic carbene complexes of Ni and Pd were shown to catalyze the hydrosilylation of allenes with a limited number of silanes to produce a variety of vinyl- and allylsilanes.271 In addition to the characterization of several new silane products, this previous work clearly demonstrated the effect of ligand steric bulk on the observed hydrosilylation regioselectivity with allyl- or vinylsilane products dictated by a combination of NHC steric bulk and metal center used. The vinylsilanes formed in this process were subsequently utilized as coupling reagents in Hiyama reactions with iodoarenes leading to the successful development of a one-pot Pd catalyzed regioselective hydrosilylation/cross coupling method.248 Also, as noted above, this allene hydrosilylation was recently investigated by DFT,266 further supporting the proposed mechanism operable in these reactions.

Over the past decade, our research group has isolated a variety of cationic allylpalladium complexes supported by 3-iminophosphine ligands, each of which has been fully characterized with many studied by X-ray crystallography.114, 116, 182, 208 The 3- iminophosphine (3IP) ligands supporting these catalysts are made using a versatile synthetic method, starting from known α,β-unsaturated chloroaldehydes. Treatment with 88

a primary amine forms the chloroimine through a Schiff base condensation, while an anionic phosphide is used to directly displace the chloride producing the final 3- iminophosphine.275 The resulting 3IP is stable to slightly acidic and basic conditions and can be kept on the benchtop for several days before undergoing slow oxidation of the phosphine. Palladium complexes of these 3IP ligands have shown excellent catalytic utility for reactions such as aryl amination and the intermolecular hydroamination of terminal alkynes, conjugated dienes, and a wide range of mono- and disubstituted allenes.117, 118

In our ongoing efforts to expand the range of their reactivity, we recently discovered that our (3-iminophosphine)palladium complexes function as active catalysts for the hydrosilylation of allenes with phenyl- and diphenylsilane. An especially notable feature of this system is the formation of new vinyl- and allylsilanes under very mild conditions with complete regioselectivity and high catalytic activity. In contrast to the work reported by Montgomery,271 the observed regioselectivity with the

[(3IP)Pd(allyl)]OTf complex is dictated entirely by the nature of the silane used.

Interestingly, in testing a wide range of silanes, in any case where catalytic activity was observed, only one regioisomer was detected spectroscopically and each was readily isolated.

4.2 Results and Discussion

All the reactions described herein were performed in NMR tubes prepared in a nitrogen-filled glovebox and in each case, the reaction was monitored spectroscopically until apparent completion was achieved by 1H NMR. Subsequently, all products were 89

then isolated by passage through a plug of silica to remove the catalyst and further characterized. Initial experiments showed that the reactions of cyclohexylallene with phenyl- and diphenylsilane were each complete in less than 30 minutes, yielding the allylsilane regioisomer as the only observed product of each reaction (Scheme 19). In an effort to more distinctly compare the reactivity of these two hydrosilanes, these reactions were repeated with a lower catalyst loading (0.2 mol%) and the percent conversion was determined after 1 hour by 1H NMR spectroscopy. The results revealed a fairly reduced reaction rate for diphenylsilane (14.5% conversion) compared to phenylsilane (38.2% conversion). Furthermore, no hydrosilylation product was observed with triphenylsilane, even with higher catalyst loading. Thus, the results for hydrosilylation using PhxSiHy appear to be directly correlated to silane steric bulk.

Scheme 19. Catalytic hydrosilylation of cyclohexylallene to form new allylsilanes.

Given the catalytic competence of this (3IP)palladium complex, we screened a wide range of silanes for the hydrosilylation of cyclohexylallene (Table 7). Interestingly, in each case, 1H NMR spectroscopy indicated that only one regioisomer was formed.

Since the only variable in this reaction is the silane, the regioselectivity of each product seemed to be directly correlated to the steric bulk of the silane. Silanes 12a-d, all of which are primary or secondary silanes, produced only the allylsilane product. In 90

contrast, the vinylsilane product was formed for each of the tertiary silanes 12e-i. The trend in reaction completion times involved a combination of weaker bond strength (with phenyl groups activating the Si-H bond) and reduced steric bulk each giving rise to faster reactions.

Table 8. Catalytic hydrosilylation of cyclohexylallene.a

Entry Silane Product Time (h)b Isolated yield (%)

PhSiH 1 3 0.5 92 (12a) (13a)

Ph SiH 2 2 2 0.5 87 (12b) (13b)

PhMeSiH 3 2 1 82 (12c) (13c)

iPr SiH 4 2 2 4 75 (12d) (13d)

Et SiH 5 3 8 82 (12e) (13e)

nPr SiH 6 3 12 79 (12f) (13f)

PhMe SiH 7 2 0.5 91 (12g) (13g)

Ph MeSiH 8 2 4 94 (12h) (13h)

1,4- (Me2SiH)2 9 c 1 89 C6H4 (13i) (12i)

10 Ph3SiH NR - - (12j)

i 11 Pr3SiH NR - - (12k)

t 12 BuMe2SiH NR - - (12l)

13 (EtO) SiH NR 3 - - (12m)

14 Cl3SiH NR - - (12n)

a Catalytic procedure: Reactions were carried out at ambient temperature in NMR tubes prepared in a glovebox using CDCl3 (800 µl), catalyst (0.005 mmol), hydrosilane (0.5 mmol), and cyclohexylallene (0.5 mmol); b Reaction completion was monitored and recorded by 1H NMR spectroscopy; c 2 eq. of cyclohexylallene were used, due to the presence of two Si-H sites.

In the reactions of the sterically unhindered silanes 12a-d with cyclohexylallene, allylsilanes bearing the silane on the more substituted carbon were formed rapidly, while the more sterically bulky silanes 12e-i generally reacted slower and gave only the vinylsilane products where the silyl group was added to the internal allene carbon atom.

Table 9. Catalytic hydrosilylation of dimethylallene.a

Entry Silane Product Time (h)b Isolated yield (%)

PhSiH 15 3 1.5 87 (12a) (14a) Ph SiH 16 2 2 2 98 (12b) (14b) PhMeSiH 17 2 14 75 (12c) (14c) 93

iPr SiH 18 2 2 10 79 (12d) (14d)

Et SiH 19 3 12 86 (12e) (14e) nPr SiH 20 3 24 76 (12f) (14f)

PhMe SiH 21 2 10 85 (12g) (14g) Ph MeSiH 22 2 NR - (12h) 1,4- (Me2SiH)2 23 c 2 94 C6H4 (12i) (14i) 24 Ph3SiH NR - (12j) i 25 Pr3SiH NR - (12k) t 26 BuMe2SiH NR - (12l) 27 (EtO)3SiH NR - (12m) 28 Cl3SiH NR - (12n) a Catalytic procedure: Reactions were carried out at ambient temperature in NMR tubes prepared in a glovebox using CDCl3 (800 µl), catalyst (0.005 mmol), hydrosilane (0.5 mmol), and dimethylallene (0.5 mmol); b Reaction completion was monitored and recorded by 1H NMR spectroscopy; c 2 eq. of dimethylallene were used, due to the presence of two Si-H sites.

In a second set of catalytic tests, dimethylallene was treated with silanes 12a-n in order to compare the regioselectivity obtained when using a disubstituted allene (Table

8). We were somewhat surprised to find that the same regioselectivity occurs with both

allenes. We expected that the additional substituent on dimethylallene would affect the regioselectivity, at least in the allylsilane cases (14a-d), possibly causing a change to the vinylsilane product or a mixture of regioisomeric products. It was fascinating that no change in final product regioselectivity was observed and Si-H addition occurred identically to that seen for the monosubstituted allene (cyclohexylallene). Seemingly, the only effect of two groups on the terminal carbon of the allene was to slow down the reaction, results in longer times to reach completion. This contrasts distinctly with

Montgomery’s work, who observed that when a disubstituted allene was utilized, an allylsilane was preferentially formed in which the silyl group added to the CH2 allene terminus giving a regioisomer that was never observed in our work.271

As proposed by Chalk and Harrod, the mechanism for the hydrosilylation of C=C bonds is assumed to be very similar to that for the hydrogenation of alkenes, in which activation of olefin by coordination of C=C to the metal center and cleavage of Si-H

(instead of H-H) are necessities.133 When these two conditions are fulfilled, the insertion of C=C into the M-H or M-Si bonds will occur, known as hydrometalation and silylmetalation, respectively.131 Silylmetalation rates were studied in detail by Brookhart, who concluded that the insertion of C=C into Pd-Si bonds is very likely to be the rate determining step in the hydrosilylation of alkenes.263 Whether insertion of C=C proceeds via hydro- or silylmetalation, the catalytic intermediate subsequently undergoes sigma bond metathesis to form the product. Mechanistic preference for silylmetalation versus hydrometalation not only affects the rate of the catalysis, but can also influence the product regioselectivity, as observed in Montgomery’s allene hydrosilylation,271 which was later supported by theoretical calculations.266 95

Based on the regioselectivity observed in our catalytic reactions, we propose two complementary mechanistic pathways for this process dictated by the sterics of the silane used (Scheme 20). Pathway I is favored by the trisubstituted silanes, while less bulky mono- and disubstituted silanes prefer pathway II. In both cases, catalyst activation is achieved via σ-bond metathesis to form the active Pd-H or Pd-[Si] catalyst, since oxidative addition of hydrosilane to Pd(II) with formation of Pd(IV) is unfavorable. Next, insertion of the allene takes place into either the Pd-Si or Pd-H bond (depending on the pathway) to give the corresponding palladium(allyl) complex. Reaction with the substrate silane proceeds through a four-centered transition state with silane steric bulk playing a key role in the regiochemistry that is set during this step. Transition state a yields the vinylsilane and places Pd-Si back into the catalytic cycle, while transition state b leads to the allylsilane product with return of the active Pd-H catalyst into the cycle. Based on the observed regioselectivity and reaction completion times (Tables 7 and 8), we conclude that regioselectivity (pathway I or II) is dependent on the sterics of the silane whereas reaction completion time relies on both the steric bulk and bond strength of the silane. As further support for the proposed mechanism, we undertook a double-labelled crossover

i experiment in which Ph2SiD2 and Pr2SiH2 (0.5 eq. each) were used in the catalytic hydrosilylation of cyclohexylallene. This reaction reached completion after four hours and 1H and 2H NMR spectroscopy revealed the production of a 1:1:1:1 mixture of

i Ph2SiDCH(Cy)CH=CH2, Ph2SiDCH(Cy)CD=CH2, Pr2SiHCH(Cy)CH=CH2, and i Pr2SiHCH(Cy)CD=CH2. Thus, statistical H/D scrambling into the vinylic position was observed, while there were undetectable levels of Si-H/Si-D scrambling. These crossover

results are consistent with the proposed sigma-bond metathesis mechanism, while they similarly discount the possibility of silane oxidative addition to Pd(0) intermediates.

Scheme 20. Proposed catalytic cycles for hydrosilylation of allenes by [(3IP)Pd(allyl)]OTf precatalyst (L = 3-iminophosphine; R’’ = H, alkyl, aryl; [Si] = SiR’’3; R = R’ = methyl for dimethylallene or R = H and R’ = cyclohexyl for cyclohexylallene).

4.3 Experimental Section

General methods and instrumentation: [(3IP)Pd(allyl)]OTf catalyst was synthesized via the reported procedure.208 All NMR-scale reactions were set up in a nitrogen-filled glovebox. CDCl3 was purchased from Cambridge Isotope Laboratories, dried over calcium hydride, freeze-pumped-thawed three times, vacuum transferred, and stored over molecular sieves in the glovebox. Cyclohexylallene and dimethylallene were supplied by Alfa Aesar and Sigma-Aldrich, respectively. All of the hydrosilanes 97

(phenylsilane, diphenylsilane, triphenylsilane, triethylsilane, tri-n-propylsilane, tri- isopropylsilane, di-isopropylsilane, methyldiphenylsilane, dimethylphenylsilane, methylphenylsilane, 1,4-bis(dimethylsilyl)benzene, tert-butyldimethylsilane, triethoxysilane and trichlorosilane) were purchased from either Acros or Gelest and freeze-pump-thawed three times before transferring into the glovebox. 1H and 13C NMR data were obtained on a 400 MHz Varian VXRS NMR spectrometer at 399.95 MHz for

1H NMR and 100.56 MHz for 13C NMR. HMQC and gCOSY experiments to analyze the

1H NMR and 13C NMR spectra of 3c (to characterize diastereomers) were performed on a

600 MHz Bruker Avance III at 599.9 MHz for 1H NMR and 150.8 MHz for 13C NMR.

High resolution mass spectrometry data were determined by the University of Illinois

Mass Spectrometry Laboratory, Urbana, IL, USA.

Catalytic reactions and isolation: All catalytic reactions were set up inside a nitrogen-filled glovebox in an NMR tube. Allene (0.50 mmol) was added to a mixture of

Pd catalyst (1 mol%, 3.2 mg) and hydrosilane (0.50 mmol) in 800 µl CDCl3. Formation of the product and reaction completion time were monitored by 1H NMR spectroscopy.

After reaction completion, the reaction mixture was concentrated under vacuum and the product was extracted with hexane and passed through a small silica gel-packed column to remove the catalyst residue. All volatiles were removed under vacuum to give the product as a colorless liquid. Catalytic products 13e,271 13g248 and 14b276 were reported previously and the reported 1H NMR data were used as a reference. 13e, 13g and 14b were isolated as colorless liquids with isolated yields of 82%, 91% and 98%, respectively.

(1-Cyclohexylallyl)(phenyl)silane (13a): Colorless liquid (106 mg, 92%). 1H NMR

3 3 3 (CDCl3) δ 7.62 (dm, JH-H= 7.8 Hz, 2H), 7.44-7.37 (m, 3H), 5.80 (dt, JH-H= 16.8 Hz, JH-

3 2 3 H= 10.2 Hz, 1H), 4.98 (dd, JH-H= 10.2 Hz, JH-H= 1.8 Hz, 1H), 4.90 (dd, JH-H= 16.8 Hz,

2 2 3 2 JH-H= 1.8 Hz, 1H), 4.41 (dd, JH-H= 6.6 Hz, JH-H= 2.4 Hz, 1H), 4.35 (dd, JH-H= 6.6 Hz,

3 13 1 JH-H= 3.6 Hz, 1H), 2.02-1.96 (m, 1H), 1.89-1.54 (m, 6H), 1.31-1.06 (m, 5H); C{ H}

NMR (CDCl3) δ 138.1, 135.9, 132.0, 129.7, 127.9, 114.5, 39.2, 38.2, 33.5, 32.2, 26.73,

+ 26.68, 26.5; HRMS (EI) (m/z): [M] calc for C15H22Si, 230.1491; found, 230.1490.

(1-Cyclohexylallyl)diphenylsilane (13b): Colorless liquid (133 mg, 87%). 1H NMR

3 3 (CDCl3) δ 7.72-7.68 (m, 4H), 7.47-7.41 (m, 6H), 5.87 (dt, JH-H= 16.8 Hz, JH-H= 10.8 Hz,

3 3 2 1H), 5.06 (d, JH-H= 3.0 Hz, 1H), 5.02 (dd, JH-H= 10.8 Hz, JH-H= 1.8 Hz, 1H), 4.94 (dd,

3 2 JH-H= 16.8 Hz, JH-H= 1.8 Hz, 1H), 2.30-2.25 (m, 1H), 1.93-1.67 (m, 6H), 1.29-1.12 (m,

13 1 5H); C{ H} NMR (CDCl3) δ 137.3, 136.0, 135.6, 134.2, 133.8, 129.6, 128.0, 127.9,

+ 115.2, 39.7, 38.9, 33.9, 31.9, 26.8, 26.7, 26.4; HRMS (EI) (m/z): [M] calc for C21H26Si,

306.1804; found, 306.1809.

(1-Cyclohexylallyl)(methyl)(phenyl)silane (13c) as 50/50 mixture of diastereomers:

Colorless liquid (100 mg, 82%).

1 3 Diastereomer A: H NMR (CDCl3) δ 7.58-7.56 (m, 2H), 7.41-7.36 (m, 3H), 5.77 (dt, JH-

3 3 2 H= 17.2 Hz, JH-H= 10.2 Hz, 1H), 4.95 (dd, JH-H= 10.2 Hz, JH-H= 2.2 Hz, 1H), 4.82 (dd,

2 17.2 Hz, JH-H= 2.2 Hz, 1H), 4.48-4.46 (m, 1H), 1.87-1.63 (m, 6H), 1.52-1.48 (m, 1H),

3 13 1 1.28-0.99 (m, 5H), 0.37 (d, JH-H= 3.6 Hz, 3H); C{ H} NMR (CDCl3) δ 137.60, 135.61,

134.89, 129.31, 127.80, 114.21, 40.50, 38.59, 33.71, 31.92, 26.79, 26.68, 26.51, -6.65.

1 3 Diastereomer B: H NMR (CDCl3) δ 7.58-7.56 (m, 2H), 7.41-7.36 (m, 3H), 5.69 (dt, JH-

3 3 2 H= 17.2 Hz, JH-H= 10.2 Hz, 1H), 4.97 (dd, JH-H= 10.2 Hz, JH-H= 2.2 Hz, 1H), 4.84 (dd,

2 17.2 Hz, JH-H= 2.2 Hz, 1H), 4.50-4.48 (m, 1H), 1.87-1.63 (m, 6H), 1.55-1.53 (m, 1H),

3 13 1 1.28-0.99 (m, 5H), 0.39 (d, JH-H= 3.6 Hz, 3H); C{ H} NMR (CDCl3) δ 138.00, 136.15,

135.10, 129.33, 127.84, 113.97, 40.95, 38.91, 33.77, 32.38, 26.81, 26.75, 26.53, -6.16.

+ HRMS (EI) (m/z): [M] calc for C16H24Si, 244.1647; found, 244.1645.

(1-Cyclohexylallyl)diisopropylsilane (13d): Colorless liquid (89 mg, 75%). 1H NMR

3 3 3 2 (CDCl3) δ 5.76 (dt, JH-H= 16.2 Hz, JH-H= 11.0 Hz, 1H), 4.89 (dd, JH-H= 11.0 Hz, JH-H=

3 2 2.2 Hz, 1H), 4.87 (dd, JH-H= 16.2 Hz, JH-H= 2.2 Hz, 1H), 3.53 (s, 1H), 1.84-1.46 (m,

3 13 1 7H), 1.29-0.89 (m, 7H), 1.07 (d, JH-H= 5.5 Hz, 12H); C{ H} NMR (CDCl3) δ 139.2,

100

113.5, 39.0, 38.3, 33.9, 32.3, 26.9, 26.6, 20.1, 19.3, 10.8, 10.5; HRMS (EI) (m/z): [M]+ calc for C15H30Si, 238.2117; found, 238.2122.

(3-Cyclohexylprop-1-en-2-yl)tripropylsilane (13f): Colorless liquid (111 mg, 79%). 1H

2 4 2 NMR (CDCl3) δ 5.56 (dt, JH-H= 3.3 Hz, JH-H= 1.5 Hz, 1H), 5.32 (d, JH-H= 3.3 Hz, 1H),

3 1.98 (d, JH-H= 7.0 Hz, 2H), 1.72-1.64 (m, 5H), 1.39-1.27 (m, 7H), 1.24-1.16 (m, 3H),

3 13 1 0.96 (t, JH-H= 7.3 Hz, 9H), 0.89-0.81 (m, 2H), 0.61-0.53 (m, 6H); C{ H} NMR

(CDCl3) δ 148.1, 126.4, 45.3, 36.6, 33.7, 26.9, 26.6, 18.8, 17.6, 15.2; HRMS (EI) (m/z):

+ [M] calc for C18H36Si, 280.2586; found, 280.2578.

(3-Cyclohexylprop-1-en-2-yl)dimethyl(phenyl)silane (13g):248 Colorless liquid (118

1 2 mg, 91%). H NMR (CDCl3) δ 7.59-7.57 (m, 2H), 7.41-7.39 (m, 3H), 5.69 (dt, JH-H= 3.0

4 2 3 Hz, JH-H= 1.8 Hz, 1H), 4.50 (d, JH-H= 3.0 Hz, 1H), 2.08 (d, JH-H= 7.2 Hz, 2H), 1.69-1.66

(m, 5H), 1.36-1.29 (m, 1H), 1.15-1.11 (m, 3H), 0.86-0.78 (m, 2H), 0.44 (s, 6H); 13C{1H}

NMR (CDCl3) δ 149.1, 138.8, 134.2, 129.1, 127.9, 127.5, 45.2, 36.7, 33.6, 26.9, 26.6, -

+ 2.5; HRMS (EI) (m/z): [M] calc for C17H26Si, 258.1804; found, 258.1814.

(3-Cyclohexylprop-1-en-2-yl)(methyl)diphenylsilane (13h): Colorless liquid (151 mg,

1 3 4 94%). H NMR (CDCl3) δ 7.63 (dd, JH-H= 8.4 Hz, JH-H= 1.8 Hz, 4H), 7.47-7.42 (m, 6H),

2 4 2 3 5.89 (dt, JH-H= 3.3 Hz, JH-H= 1.1 Hz, 1H), 5.54 (d, JH-H= 3.3 Hz, 1H), 2.19 (d, JH-H=

101

7.2 Hz, 2H), 1.74-1.66 (m, 5H), 1.38-1.29 (m, 1H), 1.17-1.11 (m, 3H), 0.90-0.84 (m, 2H),

13 1 0.76 (s, 3H); C{ H} NMR (CDCl3) δ 146.8, 136.4, 135.2, 129.9, 129.3, 127.9, 44.9,

+ 36.4, 33.4, 26.7, 26.5, -3.7; HRMS (EI) (m/z): [M] calc for C22H28Si, 320.1960; found,

320.1965.

1,4-bis((3-Cyclohexylprop-1-en-2-yl)dimethylsilyl)benzene (13i): Colorless liquid (195

1 2 4 mg, 89%). H NMR (CDCl3) δ 7.55 (s, 4H), 5.68 (dt, JH-H= 3.3 Hz, JH-H= 1.1 Hz, 2H),

2 3 5.49 (d, JH-H= 3.3 Hz, 2H), 2.07 (d, JH-H= 7.0 Hz, 4H), 1.67-1.63 (m, 10H), 1.36-1.10

13 1 (m, 8H), 0.85-0.80 (m, 4H), 0.42 (s, 12H); C{ H} NMR (CDCl3) δ 148.9, 139.3, 133.2,

+ 127.3, 45.1, 36.6, 33.5, 26.8, 26.5, -2.7; HRMS (EI) (m/z): [M] calc for C28H46Si2,

438.3138; found, 438.3156.

(2-Methylbut-3-en-2-yl)(phenyl)silane (14a): Colorless liquid (77 mg, 87%). 1H NMR

3 4 3 (CDCl3) δ 7.60 (dd, JH-H= 7.8 Hz, JH-H= 1.2 Hz, 2H), 7.45-7.37 (m, 3H), 5.96 (dd, JH-

3 3 2 H= 17.4 Hz, JH-H= 10.8 Hz, 1H), 4.98 (dd, JH-H= 10.8 Hz, JH-H= 1.2 Hz, 1H), 4.85 (dd,

3 2 13 1 JH-H=17.4 Hz, JH-H=1.2 Hz, 1H), 4.21 (s, 2H), 1.19 (s, 6H); C{ H} NMR (CDCl3) δ

145.9, 136.2, 131.5, 129.9, 127.9, 110.6, 26.1, 23.7; HRMS (EI) (m/z): [M]+ calc for

C11H16Si, 176.1021; found, 176.1023.

102

Methyl(2-methylbut-3-en-2-yl)(phenyl)silane (14c): Colorless liquid (71 mg, 75%). 1H

3 4 NMR (CDCl3) δ 7.56 (dd, JH-H= 7.8 Hz, JH-H= 1.2 Hz, 2H), 7.43-7.37 (m, 3H), 5.90 (dd,

3 3 3 2 JH-H= 17.2 Hz, JH-H= 10.6 Hz, 1H), 4.97 (dd, JH-H= 10.6 Hz, JH-H= 1.5 Hz, 1H), 4.80

3 2 3 (dd, JH-H= 17.2 Hz, JH-H= 1.5 Hz, 1H), 4.19 (t, JH-H= 3.7 Hz, 1H), 1.12 (s, 3H), 1.10 (s,

3 13 1 3H), 0.38 (d, JH-H= 3.7 Hz, 3H); C{ H} NMR (CDCl3) δ 146.1, 135.4, 134.7, 129.6,

+ 127.7, 110.1, 26.7, 23.2, 23.0, -8.3; HRMS (EI) (m/z): [M] calc for C12H18Si, 190.1178; found, 190.1179.

Diisopropyl(2-methylbut-3-en-2-yl)silane (14d): Colorless liquid (73 mg, 79%). 1H

3 3 3 NMR (CDCl3) δ 5.99 (dd, JH-H= 17.2 Hz, JH-H= 10.6 Hz, 1H), 4.87 (dd, JH-H= 10.6 Hz,

2 3 2 JH-H= 1.5 Hz, 1H), 4.80 (dd, JH-H= 17.2 Hz, JH-H= 1.5 Hz, 1H), 3.33 (s, 1H), 1.15 (s,

13 1 6H), 1.13-1.08 (m, 14H); C{ H} NMR (CDCl3) δ 147.7, 109.1, 24.8, 20.6, 19.8, 11.3;

+ HRMS (EI) (m/z): [M] calc for C11H24Si, 184.1647; found, 184.1644.

Triethyl(3-methylbut-1-en-2-yl)silane (14e): Colorless liquid, (79 mg, 86%). 1H NMR

2 4 2 (CDCl3) δ 5.71 (dd, JH-H= 2.4 Hz, JH-H= 1.2 Hz, 1H), 5.30 (d, JH-H= 2.4 Hz, 1H), 2.40

3 4 3 3 (septd, JH-H= 6.6 Hz, JH-H= 1.2 Hz, 1H), 1.02 (d, JH-H= 6.6 Hz, 6H), 0.93 (t, JH-H= 7.8

3 13 1 Hz, 9H), 0.062 (q, JH-H= 7.8 Hz, 6H); C{ H} NMR (CDCl3) δ 155.7, 122.9, 32.5, 23.2,

+ 7.6, 3.3; HRMS (EI) (m/z): [M] calc for C11H24Si, 184.1647; found, 184.1646.

103

(3-Methylbut-1-en-2-yl)tripropylsilane (14f): Colorless liquid (86 mg, 76%). 1H NMR

2 4 2 (CDCl3) δ 5.68 (dd, JH-H= 2.6 Hz, JH-H= 1.1 Hz, 1H), 5.28 (d, JH-H= 2.6 Hz, 1H), 2.40

3 4 3 (septd, JH-H= 6.6 Hz, JH-H= 1.1 Hz, 1H), 1.36-1.26 (m, 6H), 1.01 (d, JH-H= 6.6 Hz, 6H),

3 13 1 0.95 (t, JH-H= 6.9 Hz, 9H), 0.62-0.58 (m, 6H); C{ H} NMR (CDCl3) δ 156.5, 122.6,

+ 32.4, 23.2, 18.8, 17.6, 15.3; HRMS (EI) (m/z): [M] calc for C14H30Si, 226.2117; found,

226.2117.

Dimethyl(3-methylbut-1-en-2-yl)(phenyl)silane (14g): Colorless liquid (87 mg, 85%).

1 2 4 H NMR (CDCl3) δ 7.62-7.58 (m, 2H), 7.42-7.39 (m, 3H), 5.82 (dd, JH-H= 2.4 Hz, JH-H=

2 3 3 1.2 Hz, 1H), 5.48 (d, JH-H= 2.4 Hz, 1H), 4.59 (sept, JH-H= 6.1 Hz, 1H), 1.03 (d, JH-H=

13 1 6.1 Hz, 6H), 0.45 (s, 6H); C{ H} NMR (CDCl3) δ 157.0, 139.0, 134.1, 129.0, 127.8,

+ 123.8, 33.0, 23.2, -2.2; HRMS (EI) (m/z): [M] calc for C13H20Si, 204.1334; found,

204.1334.

1,4-Bis(dimethyl(3-methylbut-1-en-2-yl)silyl)benzene (14i): Colorless liquid (155 mg,

1 2 4 94%). H NMR (CDCl3) δ 7.54 (s, 4H), 5.79 (dd, JH-H= 2.5 Hz, JH-H= 1.1 Hz, 2H), 5.45

2 3 4 3 (d, JH-H= 2.5 Hz, 2H), 2.49 (septd, JH-H= 6.9 Hz, JH-H= 1.1 Hz, 2H), 1.01 (d, JH-H= 6.9

13 1 Hz, 12H), 0.43 (s, 12H); C{ H} NMR (CDCl3) δ 157.0, 133.3, 125.4, 123.7, 32.9, 23.2,

+ -2.25; HRMS (EI) (m/z): [M] calc for C20H34Si2, 330.2199; found, 330.2203.

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Crossover experiment: Diphenylsilane-d2 was supplied by Santa Cruz

Biotechnology and transferred to the glovebox as received. Into two separate vials in the glovebox, Pd catalyst (0.5 mol%, 1.6 mg) and 400 µl CDCl3 were added, followed by addition of diphenylsilane-d2 (0.25 mmol) to the first vial and diisopropylsilane (0.25 mmol) to the second vial. To each of these, cyclohexylallene (0.25 mmol) was added and then they were mixed. After 4 hours, reaction completion was observed by 1H NMR spectroscopy. The resultant 1H NMR and 2H NMR spectra confirmed formation of four products (Scheme 1):

Figure 13. Products formed in crossover experiment.

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+ + +

7.63 7.62 7.61 7.41 7.39 7.39 7.37 7.35 7.26 5.85 5.84 5.81 5.80 5.78 5.77 5.74 5.05 4.94 4.93 4.90 4.89 4.88 4.83 3.56 2.19 2.17 1.76 1.73 1.70 1.67 1.16 1.14 1.13 1.11 1.09 1.08 1.06 1.04 0.90

11.5 11.0 10.5 10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5

Internal vinylic resonances (crossover experiment products)

106

External vinylic resonances (crossover experiment products)

4.4 Conclusion

In conclusion, we successfully achieved catalytic hydrosilylation of cyclohexyl- and dimethylallene with various hydrosilanes using a [(3IP)Pd(allyl)]OTf precatalyst with high efficiency (1 mol% catalyst loading) at ambient temperature. The catalyst showed excellent reactivity for the hydrosilylation of allenes with phenyl- and diphenylsilanes, the first regioselective examples using these silanes. Overall, these catalytic experiments led to the formation of many new silicon-containing molecules in moderate to high isolated yields. We were also able to understand the effect of silane substituents on the reactivity and regioselectivity. The catalytic reactions were regiospecific in every case, as tested by the usage of a mono- and a disubstituted allene.

107

The new products can serve as potential substrates for further coupling reactions or could be used in one pot reactions directly, since only a single isomer is formed in every case.

108

Chapter 5

Catalytic Hydrosilylation of Imines, Ketones, and Alkynes Utilizing Cationic 3-Iminophosphine Complexes of Palladium and Nickel

5.1 Introduction

Hydrosilylation is an interesting catalytic transformation that facilitates access to organosilicon compounds.132 Among the available organosilicon products, allyl- and vinylsilanes have been targets of catalytic hydrosilylation reactions because of their indispensable role as substrates in coupling reactions.64, 248, 277-279 In addition to the hydrosilylation of carbon-carbon unsaturated bonds, the number of reports on catalytic hydrosilylation of carbon-heteroatom unsaturated systems as a selective reduction tool has grown rapidly.150, 152, 155, 158, 280-285 While there are many reports of olefin hydrosilylation, common catalysts for hydrosilylation of C=C bonds are second or third row late transition metals, and efforts to take advantage of first row transition metals have only recently garnered a great deal of interest.65, 279, 286-293 This is likely inspired by the very common usage of first row transition metals in the hydrosilylation of carbonyl or imine groups, although selectivity remains a challenge in this chemistry.

Allylamines are fundamentally important organic building blocks, especially as moieties within chiral amines because of their occurrence in natural products and 109

pharmaceuticals.60, 84 Many modern efforts in the development of new synthetic strategies facilitating amine synthesis have targeted catalytic hydroamination reactions for the addition of primary and secondary amines to C-C unsaturated bonds.60, 61, 115-117, 294

Alternatively, catalytic hydrosilylation has been extensively used to form new C-Si bonds246, 248, 271, 291, 295 with many examples utilizing catalytic hydrosilylation or hydrogenation as a means to form amines from imines or amides.136-138, 161, 296, 297 Overall, successes in functional group tolerance, chemoselectivity, and enantioselectivity in imine hydrosilylation/reduction demonstrated by various research groups have garnered much interest in this field.157, 159, 160, 298, 299 To date, numerous examples of metal catalyzed imine hydrosilylation/reduction have been reported, often utilizing titanium,300 iron,159, 297 zinc,138, 301 ruthenium,302 rhodium, or iridium.131, 136, 182, 296, 303 Although highly active metal and even metal-free examples of imine hydrosilylation have been reported, they often suffer from a lack of selectivity for the imine in reduction reactions or very poor overall functional group tolerance.159, 304, 305 Furthermore, there are only a few examples of palladium-catalyzed hydrosilylation of imines, and no comprehensive study of substrate scope with palladium catalysts for this transformation has been undertaken.303,

306 With regard to palladium-catalyzed imine reduction, many recent hydrogenation examples, especially those involving the asymmetric hydrogenation of imines, require

PMP or tosyl protected imines while displaying a relatively limited substrate scope.307

This raises the need for the development of useful new catalysts with broad substrate tolerance in the palladium-catalyzed reduction of imines.

Recently, we demonstrated that cationic complexes of the type [(3- iminophosphine)Pd(allyl)]+ successfully catalyze the efficient and regioselective 110

hydrosilylation of allenes.246 We also postulated that in this process, the catalyst activated primary and secondary hydrosilanes to form a Pd-H intermediate, an assertion that was further supported by an H/D crossover experiment.246 Since allylamines have broad significance in synthetic chemistry, we hoped to utilize the hydrosilane activation in our system to effect the catalytic hydrosilylation of allylimines in order to reduce them to allylamines following hydrolysis (Scheme 21).

Scheme 21. First example of palladium-catalyzed hydrosilylation/reduction of allylimines.

5.2 Results and Discussion

All catalytic reactions were performed in NMR tubes with 1H NMR spectra observed frequently to monitor reaction completion. Preliminary results showed that the hydrosilylation of 16a at room temperature was moderately slow; therefore, the reaction temperature was varied in order to find more optimal reaction conditions (Table 9).

Acceptable reaction rates were observed with mild heating (40-50 oC), while higher

111

temperatures resulted in the formation of a complex mixture of products due to uncharacterized competing side reactions.

Table 10. Effect of reaction temperature.a

Temperature (oC) Completion timeb (h)

rt 24

30 16

40 8

50 6

60 4c a Catalytic procedure: Reactions were carried out in NMR tubes prepared in a glovebox using CDCl3 (800 µl), catalyst (0.025 mmol), PhSiH3 (0.6 mmol, 1.2 eq.), and allylimine (0.5 mmol, 1 eq.); b Reaction completion was monitored and recorded by 1H NMR spectroscopy by observation of the diminishing allylimine peaks. Hydrosilylated product was hydrolysed in 2 ml c of H2O to yield the secondary allylamine; Formation of side-products was detected by 1H NMR.

The best solvent was found to be CDCl3, where the reaction under the same conditions in C6D6, CD3CN, and pyridine-d5 resulted in 43, 51, and 34% conversions, respectively. In an effort to further enhance the rate of the reaction, a stronger σ-donating di-tert-butyl phosphine unit was utilized on the 3IP ligand (15b) in place of the diphenylphosphine in 15a. Using this improved ligand set reduced the completion time

112

for the hydrosilylation of 16a to 4 h at 40 oC. Having determined the better catalyst system and useful mild reaction conditions, we set out to investigate the functional group tolerance for this transformation. A variety of allylimines were synthesized via the Schiff base condensation of aromatic aldehydes with allylamine, which were then subsequently subjected to catalytic hydrosilylation (Table 10).

Table 11. Pd-catalyzed reduction of allylimines.a

Yieldc Entry Allylimine Product Timeb (h) (%)

1 4 81 (16a) (17a)

2 12 89

(16b) (17b)

3 14 79

(16c) (17c)

4 12 76

(16d) (17d)

113

5 16 82

(16e) (17e)

6 12 84

(16f) (17f)

7 12 92

(16g) (17g)

8 16 90

(16h) (17h)

9 4 84

(16i) (17i)

10 3 76

(16j) (17j)

11 2 91

(16k) (17k)

12 44 78

(16l) (17l)

13 2 89

114

(16m) (17m)

14 36 92 (16n) (17n)

15 30 83

(16o) (17o)

16 34 88

(16p) (17p)

17 - d - -

(16q)

18 3 79

(16r) (17r)

19 6 81 (16s) (17s)

20 4 89 (16t) (17t)

21 6 87

(16u) (17u)

115

22 18 84

(16v) (17v)

a Catalytic procedure: Reactions were carried out at 40 oC in NMR tubes prepared in a glovebox using CDCl3 (800 µl), catalyst (0.025 mmol), PhSiH3 (0.6 mmol, 1.2 eq.), and allylimine (0.5 mmol, 1 eq.); b Reaction completion was monitored and recorded by 1H NMR spectroscopy by observation of the diminishing allylimine peaks. Hydrosilylated product was hydrolysed in 2 ml of H2O to yield the secondary allylamine; c Isolated yield; d Catalyst decomposition occurred.

Previous reports have noted that a PdCl2/hydrosilane system can result in the cleavage of C=N moieties,306 but this reaction was not observed in our system. Instead, our system displayed clean hydrosilylation of the imine moiety for a wide range of aromatic imines, all of which underwent smooth hydrolysis in water. The necessary reaction times were highly dependent on the substituents on the aldimine aryl group with

EDG requiring shorter reaction times compared to substrates bearing EWG. It was also found that acetonitrile and benzonitrile did not react under these catalytic conditions, so this process is benign to alkyl and aryl nitriles. Further investigations revealed that ketimines were also relatively unreactive, with less than 5% conversion detected after 8 hours at room temperature using catalyst 15b. Longer reaction times with ketimines proved somewhat effective, although the crude product was contaminated with significant amounts of side-products (Table 11). Although the electronic character of the allylimines adequately explains the different reaction rates for aldimines, it does not clarify the low reactivity of ketimines. In our previous study of allene hydrosilylation, it was found that substrate sterics (in both the unsaturated substrate and the silane) play a

116

major role in the reactivity of the system due to the necessary formation of a σ-complex within the catalytic mechanism in which the hydrosilane must approach the palladium center. Thus, in the hydrosilylation of ketimines, the presence of the second substituent

(methyl) on the imine significantly hinders formation of this required σ-complex.

Utilizing a ketimine bearing an electron-donating methoxy group did not significantly influence the reactivity and approximately the same reaction rate as the unsubstituted ketimine was observed. Thus, it seems that for ketimines, steric hinderance in the σ- complex formation step of the catalytic cycle is more important than electronic effects in the imine aryl unit.

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Table 12. Investigation of ketimines.a

Yieldd Entry Allylimine Product Timeb (h) (%)

23 72c 68

(16w) (17w)

24 72c 53

(16x) (17x)

Similar to our previous study involving the hydrosilylation of allenes,246 we propose an analogous mechanism for the hydrosilylation of imines, in which formation of a Pd-H after treatment of the Pd-precatalyst with PhSiH3 is essential. This is followed by insertion of the imine into the Pd-H bond to generate a Pd-amido complex. The relatively stable Pd-amido complex then forms a σ-complex with PhSiH3 and produces the

118

hydrosilylated product via a 4-centered transition state (Figure 13). Such interactions commonly play important roles in hydrosilylation processes.308 It is plausible that the lone pair of nitrogen in the Pd-amido complex interacts with a d-orbital of silicon as (p- d)σ interactions are known, resulting in weakening of the Si-H bond and leading to formation of Si-N and Pd-H.309 For the aldimines tested, the strong correlation between the electronic effects of the aryl substituents and the reaction rates can be attributed to conjugation of the aryl and imine fragments of the allylimine, which must undergo insertion into the Pd-H bond in order to produce the desired product.

119

Figure 14. Proposed catalytic cycle for hydrosilylation of allylimines.

Other than our interest in the hydrosilylation of imines with [(3IP)Pd(allyl)]OTf complexes, we also investigated the hydrosilylation of alkynes and carbonyl groups, in particular electron-deficient alkynes and ketones. To better understand the role of the metal center, we tested cationic complexes of both [(3IP)Pd(allyl)]+ and [(3IP)Ni(allyl)]+ supported by the same 3-iminophosphine ligand (Figure 14).

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Figure 15. Palladium and nickel complexes (15a and 4a) for hydrosilylation study.

To begin this study, electron-deficient alkynes were examined since recent reports of palladium-catalyzed hydrosilylation of these alkynes with tertiary hydrosilanes gave vinylsilane products that are very useful coupling reagents for Hiyama coupling.310, 311

The proposed mechanism in these previous reports centered on the generation of a palladium-hydride via oxidative addition of hydrosilane to palladium.310, 311

Table 13. Hydrosilylation of electron-deficient alkynes with primary and secondary silanes catalyzed by 15a.a

18a (0.5 h, 86%) 18b (1 h, 91%)

18c (1 h, 80%) 18d (4 h, 64%)

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18e (1 h, 93%) 18f (1 h, 88%)

18g (1 h, 85%) 18h (8 h, 83%)

18ib 18jc (2 h, 93%)

18kc (3 h, 79%) 18l (14 h, 68%) a Catalytic procedure: Reactions were carried out at ambient temperature in NMR tubes prepared in a glovebox using CDCl3 (800 µl), 15a (0.01 mmol, 2 mol%), hydrosilane (0.5 mmol), and alkyne (0.5 mmol), followed by frequent monitoring of the reaction by 1H NMR spectroscopy; b Product was not isolated due to formation of complex mixture; c Reaction was carried out at 0 oC.

Precatalyst 15a regioselectively hydrosilylated electron-deficient alkynes to produce syn-addition vinylsilane products in moderate to good yields (Table 12). In nearly all previous reports of hydrosilylation of electron-deficient alkynes, tertiary silanes were utilized due to detection of further reactivity observed with primary and secondary hydrosilanes after formation of mono-hydrosilylated product, while this did not occur in our study as summarized in Table 12. Triethylsilane, tert-butyldimethylsilane, and dimethylphenylsilane did not hydrosilylate any of the electron-deficient alkynes, consistent with our proposed mechanism for precatalyst activation with tertiary silanes reacting to form the Pd-Si species as the active catalyst rather than the necessary Pd-H 122

intermediate.246 Other than the usage of these resulting vinylsilane products as substrates in Hiyama coupling, they can also be easily transformed to the corresponding vinyliodides and then utilized for Suzuki-Miyaura coupling. Although hydrosilylation of electron-deficient alkynes with primary and secondary silanes worked very well, no reactivity in the hydrosilylation of 4-octyne, diphenylacetylene or phenylmethylacetylene

(internal unactivated alkynes) was observed after 24 hours under the same catalytic conditions. For 18j and 18k, performing the catalytic reactions at room temperature gave mixtures of E and Z isomers and the reactions were complete in less than 30 minutes.

Thus, they were instead repeated at 0 oC, which lengthened the reaction time but formed solely the E isomer. After reaction completion at 0 oC to form only the E isomer, the catalytic mixture was monitored for 12 hours at room temperature but no signs of isomerization to the Z isomer were observed. As postulated in previous reports, the partial isomerization of the E isomer is very likely to occur via an insertion and β-hydride elimination sequence in the presence of Pd-H species.311

Another interesting set of substrates tested were 1,3-enynes, given the possible regioselectivity issues present as investigated recently.312 To our surprise, enynes also underwent hydrosilylation with diphenylsilane regioselectivity to form a single isomer in each case (Scheme 22). The regioselectivity and reactivity found in this case can be explained by considering intermediates formed after insertion of the unsaturated bond into Pd-H. Investigating the observed regioselectivity with phenylsilane, methylphenylsilane and diisopropylsilane was inconclusive due to the formation of complex mixtures. Regioselectivity difficulties in the hydrosilylation of 1,3-enynes were also recently discussed by Zhou and Moberg, in which reaction optimization by screening 123

different ligands led to selective internal hydrosilylation of the C-C triple bond.312 As before, tertiary silanes did not show any reactivity in the hydrosilylation of 1,3-enynes.

The Pd-Si intermediates believed to be formed after treatment of (3- iminophosphine)palladium precatalyst 15a with tertiary silanes are less reactive for olefin insertion than Pd-H species. Moreover, Pd-Si intermediates have much greater steric hindrance at the catalyst center, preventing the insertion of olefins.263

Scheme 22. Hydrosilylation of 1,3-enynes with diphenylsilane catalyzed by 15a.

To further study the intermediates present in this catalyst system, we performed equimolar reactions of palladium precatalyst 15a with diphenylsilane, and the reaction was monitored over time. Although we were not able to detect complete conversion to a distinct palladium intermediate, the formation of a Pd-H complex was observed as a triplet by proton NMR spectroscopy (JH-P=92.4 Hz; Figure 15). The existence of this hydride as a triplet can be explained by formation of a dinuclear palladium complex bearing a bridging hydride, due to the unsaturated coordination sphere in the resulting monomeric Pd-H species. Further efforts to isolate this hydride intermediate were unsuccessful, since it was not a stable species and decomposed during attempted workup.

Time-resolved 31P NMR analysis of this reaction, as recorded every 15 minutes, also showed diminishing of the precatalyst 31P resonance in tandem with a new 31P resonance growing in as a doublet (Figure 16). Interestingly, this same hydride was also formed in

124

the equimolar reactions of palladium precatalyst with either phenylsilane or methylphenylsilane (primary and secondary silanes) but was not observed in reactions with the aforementioned tertiary silanes. No precise conclusion about the catalytic activity of this Pd-H species can be made at this point though, since other species within the reaction mixture may be responsible for the observed catalytic activity.

125

Figure 16. 1H NMR spectrum for equimolar reaction of 15a and diphenylsilane, resulting in the formation of a Pd-H species.

Figure 17. Time-resolved 31P NMR spectra from equimolar reaction of 15a and diphenylsilane (recorded every 15 minutes).

126

Nickel complex 4a was also investigated in hydrosilylation reactions. Synthesis of

4a was described in Chapter 3, and it was fully characterized by NMR spectroscopy and elemental analysis. Suitable crystals were grown by layering pentane over a saturated solution of 4a in tetrahydrofuran, and its structure was determined by X-ray crystallography via direct methods solution (Figure 17).

Figure 18. Crystal structure of complex 4a (50% thermal ellipsoids).

The equimolar reaction of 4a with diphenylsilane was monitored by 1H NMR spectroscopy over time. Unlike the Pd complex 15a, no conclusion was obtained due to the uninterpretable 1H NMR spectrum of the resulting mixture. Other than the formation of a complex mixture of products, no catalytic hydrosilylation of methylpropiolate was observed over 24 hours with 5 mol% of nickel complex 4a. However, due to recent interest in the hydrosilylation of carbonyls, we set out to investigate the hydrosilylation of aldehydes and ketones utilizing 4a. Interestingly, this nickel complex proved to be active for the hydrosilylation of carbonyls. For comparison, the nickel and palladium complexes were both investigated in the hydrosilylation of benzaldehyde and acetophenone (Table

13). Initial data showed that the nickel complex was a better catalyst than palladium in

127

the hydrosilylation of C=O derivatives, forming quantitative conversion to the silylether product with both benzaldehyde and acetophenone, while the palladium complex proved to be almost inactive under these conditions.

Table 14. Catalytic activity of 15a and 4a in the hydrosilylation of benzaldehyde and acetophenone with diphenylsilane.a

Rxn time (h) Rxn time (h) Entry Substrate Solvent 15a 4a

b c 1 benzaldehyde CDCl3 NR --

b c 2 acetophenone CDCl3 NR --

b 3 benzaldehyde C6D6 NR 2

b 4 acetophenone C6D6 NR 12 a Catalytic procedure: Reactions were carried out at ambient temperature in NMR tubes prepared in a glovebox using solvent-d (800 µl), catalyst 15a or 4a (0.01 mmol, 2 mol%), hydrosilane (0.5 mmol), and carbonyl compound (0.5 mmol), followed by frequent monitoring of the reaction by 1H NMR spectroscopy; b Trace amount of product detected after 24 h at 60 oC; c < 5% conversion was observed after 24 h at rt.

In previous reports, nickel-alkoxide and nickel-hydride complexes have been synthesized directly and demonstrated activity for the hydrosilylation of carbonyl derivatives, making them plausible intermediates in the catalytic hydrosilylation of the carbonyl functional group.163, 164 In our chemistry, a nickel-hydride complex is a

128

plausible active catalyst, although more mechanistic investigations are required to further support the similarity of this system to traditional mechanisms.163, 164 The scope of carbonyl hydrosilylation with 4a is summarized in Table 14.

Table 15. Hydrosilylation of ketones with diphenylsilane catalyzed by 4a.a

Isolated yield Entry Product Time (h) (%)

1 12 94

19a

2 21 85

19b

3 36 71

19c

48 86 4 16 c

19d

5 30 66

19e

129

--b 6

19f

7 44 77

19g

8 --b

19h

9 3 89

19i

10 8 82

19j

11 36 c 76

19k

24 c 83 12 14 c,d 19l

30 c 79 13e 20 c,d

19m a Catalytic procedure: Reactions were carried out at ambient temperature in NMR tubes prepared in a glovebox using C6D6 (800 µl), 4a (0.01 mmol, 2 mol%), hydrosilane (0.5 mmol), and ketone (0.5 mmol), followed by frequent monitoring of the reaction by 1H NMR spectroscopy; b Trace amount of product was detected by 1H NMR spectroscopy; c Reaction was carried out at 60 oC; d Reaction was carried out with 5 mol% of 4a. e 2 eq. of diphenylsilane was used due to sluggish reaction with 1 eq. of hydrosilane.

130

Initial data on the hydrosilylation of ketones using 4a shows that the necessary reaction time is highly dependent on the sterics of the ketone, and that only a very small amount of product formation was detected with a bulky mesityl group present (entry 6).

Comparing entries 7 and 8 (ortho-methoxyphenyl vs ortho-chlorophenyl groups) also provides information on the advantageous effect of an electron-donating group (OMe) on the rate of the reaction. In general, as previously noted,163 electron-donating groups on the aryl unit of ketones and imines promotes η2-coordination of the carbonyl or imine to the metal center, which is required for successful insertion of the C=O or C=N group into a metal-hydride species.

It was observed that hydrosilylation of E-4-phenylbut-3-en-2-one (entry 13) resulted in exclusive formation of the 1,4-hydrosilylation product. A literature survey revealed that 1,4-hydrosilylation of α,β-unsaturated ketones has been obtained with rhodium complexes313, 314 while nearly all nickel-catalyzed examples favor direct hydrosilylation of the carbonyl functionality, with only a single exception reported recently.315 Although further investigation of other α,β-unsaturated carbonyl compounds is necessary, entry 13 shows the strength and capability of nickel as a replacement for more expensive transition metal-catalyzed systems. To test the scale-up robustness of 15a and 4a in the hydrosilylation of π-compounds, gram scale hydrosilylation reactions with both catalysts were performed, resulting in excellent yields of the desired products selectively (Scheme 23).

131

Scheme 23. Gram-scale catalytic reactions of 15a and 4a.

During the substrate screening for alkyne hydrosilylation, it was noted that nickel complex 4a worked well in the cis-hydrosilylation of internal alkynes to form the corresponding vinylsilane products (Table 15). Although a few examples of first row transition metal-catalyzed hydrosilylation of alkynes have been reported to date,65, 286, 292 overall selectivity is variable in all cases, often yielding more than one product isomer.

These previous reports include a cobalt system by Mo and coworkers that works perfectly for terminal alkynes but lacks regioselectivity with unsymmetric internal alkynes.292

Additionally, a recent report of nickel-catalyzed hydrosilylation by Srinivas and coworkers forms two regioisomers in the hydrosilylation of an unsymmetric alkyne (1- phenyl-1-propyne). This contrasts with our observation of only a single isomer with the same substrate. 65, 286, 292 Another interesting observation with our catalyst was the 132

telomerization of 1-hexyne in the presence of diphenylsilane (entry 5). In this case, reaction was carried out with 2 eq. of 1-hexyne in order to obtain full conversion, since the equimolar reaction yielded telomerized product and unreacted diphenylsilane. As with most organotransition chemistry, it should be emphasized that the reactivity and selectivity observed in catalytic hydrosilylation is highly dependent on the combination of metal and ligand used in the catalyst as well as the electronic and steric parameters of the hydrosilane.246, 271, 316

Table 16. Substrate scope of alkyne hydrosilylation catalyzed by 4a.a

Isolated yield Entry Alkyne Product Time (h) (%)

22 84 1 R1=R2=nPr 12b

20a

30 77 2 R1=R2=Ph 16b

20b

R1=Me 14 80 3 R2=Ph 10b

20c

133

R1=Et 24 81 4 R2=2-Propenyl 14b

18n

R1=nBu 36 86 5c R2=H 24b

20e a Catalytic procedure: Reactions were carried out at room temperature in NMR tubes prepared in a glovebox using C6D6 (800 µl), 4a (0.01 mmol, 2 mol%), hydrosilane (0.5 mmol), and ketone (0.5 mmol), followed by frequent monitoring of the reaction by 1H NMR spectroscopy; b Reaction was carried out at 60 oC; c 2 eq. of alkyne was used.

5.3 Experimental Section

General methods and instrumentation: All NMR-scale reactions were set up in a nitrogen-filled glovebox. CDCl3 and C6D6 were purchased from Cambridge Isotope

Laboratories and for air-sensitive usage, dried over calcium hydride and sodium, respectively, freeze-pump-thawed three times, vacuum-transferred, and stored over molecular sieves in a nitrogen-filled glovebox. The [(3IP)Pd(allyl)]OTf (15a and 15b) precatalysts were synthesized via the procedure described in Chapter 3.116 Hydrosilanes for catalytic hydrosilylation reactions were purchased from Gelest, AK Scientific, or

Acros, dried neat over calcium hydride and distilled under nitrogen, freeze-pump-thawed, and transferred to the glovebox. All aromatic aldehydes, ketones, and allylamine required to synthesize 16a-x were supplied from Alfa Aesar, AK Scientific, Sigma-Aldrich, and

Acros. Alkynes were purchased from either Sigma-Aldrich or AK Scientific. 1H and 13C

NMR data were obtained either on a 400 MHz Varian VXRS NMR spectrometer at

399.95 MHz for 1H NMR and 100.56 MHz for 13C NMR or on a 600 MHz Bruker

134

Avance III at 599.9 MHz for 1H NMR and 150.8 MHz for 13C NMR. 19F NMR was obtained on the 400 MHz Varian NMR at 376.29 MHz. High resolution mass spectrometry data were determined by the University of Illinois Mass Spectrometry

Laboratory, Urbana, IL, USA and University of Toledo Mass Spectrometry Laboratory,

Toledo, Ohio, USA.

Synthesis of allylimines: Aromatic aldehydes (1 eq.) and allylamine (1.2 eq.) were dissolved in either diethylether or dichloromethane and stirred over molecular sieves overnight. After reaction completion, the mixture was filtered, dried over MgSO4 in a Schlenk flask, cannula filtered, and then volatiles were removed under vacuum. The resulting allylimine was further degassed under vacuum, transferred to the glovebox and kept over molecular sieves in the freezer. All allylimines were characterized by 1H and

13C NMR spectroscopy with the E isomer as the major product.

Catalytic hydrosilylation of allylimines and isolation of allylamines: All catalytic reactions were set up inside a nitrogen-filled glovebox in NMR tubes.

Allylimine (0.5 mmol) was added to a mixture of PhSiH3 (0.6 mmol) and palladium precatalyst (5 mol%, 15a or 15b) dissolved in CDCl3. Temperature was controlled in an oil bath on a hot plate connected to a thermoprobe. 1H NMR spectra were collected frequently to check the reaction completion detected by disappearance of the iminic proton or corresponding starting material. Then, the mixture was hydrolyzed in H2O and extracted with diethylether (3x2 ml) and dried over either MgSO4 or Na2SO4. The dried solution was filtered through a small plug of celite and after removal of volatiles, was purified by silica column (hexanes : ethylacetate, 90 : 10). Allylamine products were characterized by 1H, 13C NMR spectroscopy, and high resolution mass spectrometry. 135

Catalytic hydrosilylation of alkynes and ketones and isolation of hydrosilylation products: For the hydrosilylation reactions of alkynes, unless otherwise noted, 15a or 4a was suspended in CDCl3 or C6D6, followed by addition of hydrosilane

(1 eq.) and alkyne (1 eq.). In the case of carbonyl hydrosilylation, the carbonyl derivative was added before the hydrosilane. Then, the resulting solution was transferred to an

NMR tube, sealed and reaction progress was monitored by acquiring 1H NMR data frequently. Gram scale reactions were set up in 20 ml vials, sealed with gentle stirring, and reaction completion was monitored by TLC analysis of the reaction mixture. After detection of reaction completion by 1H NMR (based on diminishing starting material peaks), all volatiles were removed under vacuum, and the crude reaction mixture was extracted with hexanes and passed through a short plug of silica gel to remove inorganics.

This mixture was concentrated and purified by flash chromatography (hexanes for vinylsilane products and 90:10 hexanes:ethylacetate for silylether products) as a colorless oily liquid. Isolated yields are calculated based on unsaturated substrate (alkyne or carbonyl derivative). For silylether products, due to partial hydrolysis of the product on silica gel, yields are based on total of silylether and corresponding alcohol. All vinylsilanes were characterized by 1H, 13C NMR spectroscopy, and high resolution mass spectrometry. Silylether products were characterized only by 1H and 13C NMR spectroscopy.

N-Allyl-1-phenylmethanimine (16a):317 Colorless liquid, 92% isolated yield, 1H NMR

(CDCl3, 400 MHz): 8.29 (s, 1H), 7.79-7.74 (m, 2H), 7.44-7.40 (m, 3H), 6.09 (ddt,

136

3J=17.2 Hz, 3J=10.4 Hz, 3J=5.6 Hz, 1H), 5.25 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz, 1H), 5.17

(dq, 3J=10.4 Hz, 4J=2J=1.6 Hz, 1H), 4.27 (dt, 3J=5.6 Hz, 4J=1.6 Hz, 2H); 13C{1H} NMR

(CDCl3, 400 MHz): 162.0, 136.2, 135.9, 130.7, 128.6, 128.2, 116.1, 63.6.

N-Allyl-1-(4-iodophenyl)methanimine (16b): Colorless liquid, 77% isolated yield, 1H

3 3 NMR (CDCl3, 400 MHz): 8.21 (s, 1H), 7.75 (d, J=8.4 Hz, 2H), 7.47 (d, J=8.4 Hz, 2H),

6.05 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=5.6 Hz, 1H), 5.22 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz,

1H), 5.16 (dq, 3J=10.4 Hz, 4J=2J=1.6 Hz, 1H), 4.24 (dm, 3J=5.6 Hz, 2H); 13C{1H} NMR

(CDCl3, 400 MHz): 161.0, 137.9, 135.7, 129.7, 116.4, 97.4, 63.6.

N-Allyl-1-(2-bromophenyl)methanimine (16c):318 Pale yellow oily liquid, 90% isolated

1 3 3 yield, H NMR (CDCl3, 400 MHz): 8.67 (s, 1H), 8.05 (d, J=8.0 Hz, 1H), 7.55 (d, J=8.0

Hz, 1H), 7.32 (t, 3J=8.0 Hz, 1H), 7.24 (t, 3J=8.0 Hz, 1H), 6.08 (m, 1H), 5.25 (dm, 3J=17.2

3 3 13 1 Hz, 1H), 5.18 (dm, J=10.4 Hz, 1H), 4.30 (dm, J=6.0 Hz, 2H); C{ H} NMR (CDCl3,

400 MHz) 161.0, 135.6, 134.5, 133.0, 131.9, 128.8, 127.6, 125.1, 116.4, 63.6.

N-Allyl-1-(3-bromophenyl)methanimine (16d):319 Pale yellow oily liquid, 86% isolated

1 3 yield, H NMR (CDCl3, 400 MHz): 8.18 (s, 1H), 7.92 (s, 1H), 7.60 (d, J=7.6 Hz, 1H),

7.51 (d, 3J=7.6 Hz, 1H), 7.24 (t, 3J=7.6 Hz, 1H), 6.04 (ddt, 3J=17.2 Hz, 3J=10.4 Hz,

3J=5.6 Hz, 1H), 5.22 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz, 1H), 5.16 (dq, 3J=10.4 Hz, 4J=2J=1.6 137

3 13 1 Hz, 1H), 4.24 (dm, J=5.6 Hz, 2H); C{ H} NMR (CDCl3, 400 MHz): 160.2, 138.1,

135.5, 133.5, 130.6, 130.1, 126.9, 122.9, 116.3, 63.4.

N-Allyl-1-(2-chlorophenyl)methanimine (16e):318 Colorless oily liquid, 86% isolated

1 3 4 yield, H NMR (CDCl3, 400 MHz): 8.72 (s, 1H), 8.07 (dd, J=7.6 Hz, J=2.0 Hz, 1H),

7.35-7.25 (m, 3H), 6.12-6.02 (m, 1H), 5.24 (dd, 3J=17.2 Hz, 2J=1.6 Hz, 1H), 5.17 (dd,

3 2 3 13 1 J=10.0 Hz, J=1.6 Hz, 1H), 4.29 (dm, J=5.6 Hz, 2H); C{ H} NMR (CDCl3, 400

MHz): 158.6, 135.7, 135.1, 133.1, 131.5, 129.7, 128.3, 127.0, 116.3, 63.7.

N-Allyl-1-(3-chlorophenyl)methanimine (16f):320 Colorless oily liquid, 84% isolated

1 4 3 yield, H NMR (CDCl3, 400 MHz): 8.20 (s, 1H), 7.76 (d, J=1.6 Hz, 1H), 7.55 (dt, J=7.6

Hz, 4J=1.6 Hz, 1H), 7.36-7.27 (m, 2H), 6.09-5.99 (m, 1H), 5.22 (dm, 3J=17.2 Hz, 1H),

3 3 13 1 5.15 (dm, J=10.4 Hz, 1H), 4.23 (dm, J=6.0 Hz, 2H); C{ H} NMR (CDCl3, 400 MHz):

160.3, 137.9, 135.5, 134.7, 130.6, 129.8, 127.7, 126.5, 116.3, 63.4.

N-(4-Chlorobenzyl)prop-2-en-1-amine (16g):321 Pale yellow oily liquid, 80% isolated

1 3 3 yield, H NMR (CDCl3, 400 MHz): 8.23 (s, 1H), 7.67 (d, J=8.4 Hz, 2H), 7.37 (d, J=8.4

Hz, 2H), 6.05 (ddt, 3J=17.2 Hz, 3J=10.0 Hz, 3J=5.6 Hz, 1H), 5.22 (dq, 3J=17.2 Hz,

4J=2J=1.6 Hz, 1H), 5.16 (dq, 3J=10.0 Hz, 4J=2J=1.6 Hz, 1H), 4.24 (dm, 3J=5.6 Hz, 2H);

13 1 C{ H} NMR (CDCl3, 400 MHz): 160.6, 136.7, 135.7, 134.7, 129.4, 128.9, 116.3, 63.6. 138

N-(4-Fluorobenzyl)prop-2-en-1-amine (16h):322 Pale yellow oily liquid, 83% isolated

1 yield, H NMR (CDCl3, 400 MHz): 8.25 (s, 1H), 7.76-7.71 (m, 2H), 7.12-7.06 (m, 2H),

6.06 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.23 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz,

1H), 5.15 (dq, 3J=10.4 Hz, 4J=2J=1.6 Hz, 1H), 4.24 (dm, 3J=6.0 Hz, 2H); 13C{1H} NMR

1 4 (CDCl3, 400 MHz): 164.3 (d, JCF=250.6 Hz), 160.6, 135.9, 132.6 (d, JCF=2.9 Hz), 130.1

3 2 19 1 (d, JCF=8.7 Hz), 116.2, 115.8 (d, JCF=21.9 Hz), 63.5; F{ H} NMR (CDCl3, 400

MHz): 109.9.

N-Allyl-1-(p-tolyl)methanimine (16i):322 Colorless oily liquid, 92% isolated yield, 1H

3 3 NMR (CDCl3, 400 MHz): 8.25 (s, 1H), 7.66 (d, J=8.0 Hz, 2H), 7.22 (d, J=8.0 Hz, 2H),

6.08 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=5.6 Hz, 1H), 5.27 (dq, 3J=17.2 Hz, 2J=4J=1.6 Hz,

1H), 5.16 (dq, 3J=10.4 Hz, 2J=4J=1.6 Hz, 1H), 4.25 (dm, 3J=5.6 Hz, 2H), 2.38 (s, 3H);

13 1 C{ H} NMR (CDCl3, 400 MHz): 161.8, 140.9, 136.0, 133.6, 129.3, 128.1, 115.9, 63.5,

21.5.

N-Allyl-1-(4-methoxyphenyl)methanimine (16j):321 Colorless oily liquid, 94% isolated

1 3 3 yield, H NMR (CDCl3, 400 MHz): 8.19 (s, 1H), 7.68 (d, J=8.8 Hz, 2H), 6.90 (d, J=8.8

Hz, 2H), 6.05 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=5.6 Hz, 1H), 5.22 (dq, 3J=17.2 Hz,

2J=4J=1.6 Hz, 1H), 5.13 (dq, 3J=10.4 Hz, 2J=4J=1.6 Hz, 1H), 4.20 (dm, 3J=5.6 Hz, 2H),

139

13 1 3.80 (s, 3H); C{ H} NMR (CDCl3, 400 MHz): 161.6, 161.3, 136.2, 129.7, 129.1, 115.9,

114.0, 63.5, 55.3.

4-((Allylimino)methyl)-N,N-dimethylaniline (16k):320 Colorless oily liquid, 81%

1 3 isolated yield, H NMR (CDCl3, 400 MHz): 8.14 (s, 1H), 7.63 (d, J=8.8 Hz, 2H), 6.68

(d, 3J=8.8 Hz, 2H), 6.07 (ddt, 3J=17.2 Hz, 3J=10.2 Hz, 3J=5.8 Hz, 1H), 5.23 (dq, 3J=17.2

Hz, 4J=2J=1.8 Hz, 1H), 5.14 (dq, 3J=10.2 Hz, 4J=2J=1.8 Hz, 1H), 4.20 (dm, 3J=5.8 Hz,

13 1 2H), 2.98 (s, 6H); C{ H} NMR (CDCl3, 400 MHz): 161.9, 152.0, 136.6, 129.5, 124.3,

115.5, 111.5, 63.5, 40.1.

N-(4-Nitrobenzyl)prop-2-en-1-amine (16l):323 Pale yellow solid, 86% isolated yield, 1H

3 3 NMR (CDCl3, 400 MHz): 8.38 (s, 1H), 8.26 (d, J=8.8 Hz, 2H), 7.91 (d, J=8.8 Hz, 2H),

6.07 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.24 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz,

1H), 5.19 (dq, 3J=10.4 Hz, 4J=2J=1.6 Hz, 1H), 4.32 (dm, 3J=6.0 Hz, 2H); 13C{1H} NMR

(CDCl3, 400 MHz): 159.7, 149.1, 141.7, 135.2, 128.9, 124.0, 116.8, 63.8.

N-Allyl-1-(3,4,5-trimethoxyphenyl)methanimine (16m):324 Colorless oily liquid, 86%

1 isolated yield, H NMR (CDCl3, 400 MHz): 8.15 (s, 1H), 6.96 (s, 2H), 6.05-5.97 (m, 1H),

5.19 (dm, 3J=17.2 Hz, 1H), 5.12 (dm, 3J=10.4 Hz, 1H), 4.21 (dm, 3J=5.6 Hz, 2H), 3.86 (s,

140

13 1 6H), 3.84 (s, 3H); C{ H} NMR (CDCl3, 400 MHz): 161.6, 153.4, 140.2, 135.8, 131.7,

116.2, 105.0, 63.4, 60.9, 56.2.

N-Allyl-1-(3-(trifluoromethyl)phenyl)methanimine (16n):325 Colorless oily liquid,

1 81% isolated yield, H NMR (CDCl3, 600 MHz): 8.33 (s, 1H), 8.04 (s, 1H), 7.92 (d,

3J=7.6 Hz, 1H), 7.67 (d, 3J=7.6 Hz, 1H), 7.53 (t, 3J=7.6 Hz, 1H), 6.06 (ddt, 3J=17.2 Hz,

3J=10.0 Hz, 3J=5.6 Hz, 1H), 5.25 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz, 1H), 5.18 (dq, 3J=10.0

4 2 3 13 1 Hz, J= J=1.6 Hz, 1H), 4.29 (dm, J=5.6 Hz, 2H); C{ H} NMR (CDCl3, 600 MHz):

2 3 160.4, 137.0, 135.5, 131.4, 131.2 (q, JC-F=32.7 Hz), 129.2, 127.2 (q, JC-F=3.5 Hz), 124.9

3 1 19 1 (q, JC-F=3.0 Hz), 124.0 (q, JC-F=272.2 Hz), 116.5, 63.6; F{ H} NMR (CDCl3, 400

MHz): -63.16.

4-((Allylimino)methyl)benzonitrile (16o):326 Colorless liquid, 86% isolated yield, 1H

3 3 NMR (CDCl3, 400 MHz): 8.31 (s, 1H), 7.84 (d, J=7.6 Hz, 2H), 7.68 (d, J=7.6 Hz, 2H),

6.04 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=5.6 Hz, 1H), 5.22 (dq, 3J=17.2 Hz, 2J=4J=1.6 Hz,

1H), 5.17 (dq, 3J=10.4 Hz, 2J=4J=1.6 Hz, 1H), 4.28 (dm, 3J=5.6 Hz, 2H); 13C{1H} NMR

(CDCl3, 400 MHz): 160.0, 140.0, 135.2, 132.5, 128.6, 118.6, 116.7, 114.0, 63.6.

3-((Allylimino)methyl)benzonitrile (16p): Colorless liquid, 81% isolated yield, 1H

3 NMR (CDCl3, 400 MHz): 8.27 (s, 1H), 8.03 (s, 1H), 7.94 (d, J=7.6 Hz, 1H), 7.66 (d, 141

3J=7.6 Hz, 1H), 7.50 (t, 3J=7.6 Hz, 1H), 6.03 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=6.0 Hz,

1H), 5.21 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz, 1H), 5.15 (dq, 3J=10.4 Hz, 4J=2J=1.6 Hz, 1H),

3 13 1 4.26 (dm, J=6.0 Hz, 2H); C{ H} NMR (CDCl3, 400 MHz): 159.4, 137.2, 135.2, 133.7,

132.2, 131.5, 129.5, 118.3, 116.6, 112.9, 63.4.

4-((Allylimino)methyl)-2,6-dimethoxyphenol (16q): Pale orange solid, 91% isolated

1 yield, H NMR (CDCl3, 400 MHz): 8.15 (s, 1H), 7.00 (s, 2H), 6.09-6.00 (m, 1H), 5.22

(dm, 3J=17.2 Hz, 1H), 5.14 (dm, 3J=10.2 Hz, 1H), 4.22 (dm, 3J=5.2 Hz, 2H), 3.88 (s, 6H);

13 1 C{ H} NMR (CDCl3, 400 MHz): 161.9, 147.4, 137.7, 136.1, 127.6, 116.2, 105.1, 63.4,

56.4.

N-(1,3-Benzodioxol-5-ylmethylene)-2-propen-1-amine (16r):327 Colorless liquid, 85%

1 4 isolated yield, H NMR (CDCl3, 400 MHz): 8.15 (s, 1H), 7.37 (d, J=1.6 Hz, 1H), 7.10

(dd, 3J=7.8 Hz, 4J=1.6 Hz, 1H), 6.81 (d, 3J=7.8 Hz, 1H), 6.04 (ddt, 3J=17.2 Hz, 3J=10.6

Hz, 3J=5.8 Hz, 1H), 5.98 (s, 2H), 5.21 (dq, 3J=17.2 Hz, 4J=2J=1.8 Hz, 1H), 5.14 (dq,

3 4 2 3 13 1 J=10.6 Hz, J= J=1.8 Hz, 1H), 5.20 (dm, J=5.8 Hz, 2H); C{ H} NMR (CDCl3, 400

MHz): 161.2, 149.9, 148.3, 136.1, 131.1, 124.5, 116.0, 108.1, 106.6, 101.5, 63.3.

N-Allyl-1-(furan-2-yl)methanimine (16s):328 Dark red liquid, 81% isolated yield, 1H

3 3 NMR (CDCl3, 400 MHz): 8.07 (s, 1H), 7.49 (d, J=1.6 Hz, 1H), 6.74 (d, J=3.6 Hz, 1H), 142

6.45 (dd, 3J=3.6 Hz, 3J=1.6 Hz, 1H), 6.08-5.98 (m, 1H), 5.19 (dd, 3J=17.2 Hz, 2J=1.6 Hz,

1H), 5.13 (dd, 3J=10.0 Hz, 2J=1.6 Hz, 1H), 4.20 (dd, 3J=5.6 Hz, 4J=1.2 Hz, 2H); 13C{1H}

NMR (CDCl3, 400 MHz): 151.6, 150.4, 144.8, 135.6, 116.5, 114.1, 111.7, 63.7.

N-Allyl-1-(naphthalen-2-yl)methanimine (16t):329 Colorless liquid, 91% isolated yield,

1 3 4 H NMR (CDCl3, 400 MHz): 8.39 (s, 1H), 8.08 (dd, J=8.8 Hz, J=1.1 Hz, 1H), 8.02 (s,

1H), 7.89-7.84 (m, 3H), 7.54-7.50 (m, 2H), 6.20-6.13 (m, 1H), 5.34 (dm, 3J=17.2 Hz,

3 3 13 1 1H), 5.25 (dm, J=10.3 Hz, 1H), 4.34 (dm, J=5.5 Hz, 2H); C{ H} NMR (CDCl3, 400

MHz): 162.0, 135.9, 134.7, 133.8, 133.0, 130.0, 128.6, 128.4, 127.8, 127.1, 126.4, 123.8,

116.1, 63.6.

N-Allyl-1-(naphthalen-1-yl)methanimine (16u):329 Colorless liquid, 90% isolated yield,

1 3 H NMR (CDCl3, 400 MHz): 9.00 (d, J=5.6 Hz, 1H), 8.96 (s, 1H), 7.95-7.90 (m, 3H),

7.63-7.52 (m, 3H), 6.25-6.15 (m, 1H), 5.34 (dm, 3J=17.2 Hz, 1H), 5.23 (dm, 3J=10.0 Hz,

3 13 1 1H), 4.41 (dm, J=4.4 Hz, 2H); C{ H} NMR (CDCl3, 400 MHz): 161.7, 136.2, 133.9,

131.7, 131.4, 131.1, 128.8, 128.7, 127.2, 126.1, 125.3, 124.3, 116.1, 64.6.

N-Allyl-1-(ferrocenyl)methanimine (16v):330 Dark red oily liquid, 80% isolated yield,

1 3 3 3 H NMR (CDCl3, 400 MHz): 8.13 (s, 1H), 6.03 (ddt, J=17.2 Hz, J=10.4 Hz, J=5.6 Hz, 143

1H), 5.21 (dm, 3J=17.2 Hz, 1H), 5.14 (dm, 3J=10.4 Hz, 1H), 4.66 (t, J=2.0 Hz, 2H), 4.37

3 13 1 (t, J=2.0 Hz, 2H), 4.18 (s, 5H), 4.09 (dm, J=5.6 Hz, 2H); C{ H} NMR (CDCl3, 400

MHz): 162.3, 136.5, 115.8, 80.5, 70.6, 69.2, 68.6, 63.8.

N-Allyl-1-phenylethan-1-imine (16w):331 (E:Z 91:9 by 1H NMR) Colorless oily liquid,

1 90% isolated yield, E isomer: H NMR (CDCl3, 400 MHz): 7.81-7.80 (m, 2H), 7.40-7.37

(m, 3H), 6.12 (ddt, 3J=17.4 Hz, 3J=10.2 Hz, 3J=5.4 Hz, 1H), 5.26 (dq, 3J=17.4 Hz,

4J=2J=1.8 Hz, 1H), 5.15 (dq, 3J=10.2 Hz, 4J=2J=1.8 Hz, 1H), 4.19 (d, 3J=5.4 Hz, 2H), 2.25

13 1 (s, 3H); C{ H} NMR (CDCl3, 600 MHz): 166.4, 141.3, 136.2, 129.7, 128.4, 126.8,

115.3, 54.7, 15.8.

N-Allyl-1-(4-methoxyphenyl)ethan-1-imine (16x):332 (E:Z 96:4 by 1H NMR) Colorless

1 3 oily liquid, 86% isolated yield, E isomer: H NMR (CDCl3, 600 MHz): 7.78 (dm, J=8.9

Hz, 2H), 6.89 (dm, 3J=8.9 Hz, 2H), 6.11 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=5.4 Hz, 1H),

5.24 (dq, 3J=17.2 Hz, 4J=2J=1.8 Hz, 1H), 5.14 (dq, 3J=10.4 Hz, 4J=2J=1.8 Hz, 1H), 4.16

3 13 1 (dm, J=5.4 Hz, 2H), 3.84 (s, 3H), 2.22 (s, 3H); C{ H} NMR (CDCl3, 600 MHz): 165.6,

160.9, 136.4, 133.9, 128.3, 115.1, 113.6, 55.5, 54.6, 15.4.

144

N-Benzylprop-2-en-1-amine (17a):333 Colorless liquid (60 mg, 81% isolated yield), 1H

3 NMR (CDCl3, 600 MHz): 7.34-7.31 (m, 4H), 7.28-7.24 (m, 1H), 5.94 (ddt, J=16.3 Hz,

3J=10.3 Hz, 3J=6.0 Hz, 1H), 5.20 (dq, 3J=16.3 Hz, 4J=2J=1.7 Hz, 1H), 5.13 (dq, 3J=10.3

Hz, 4J=2J=1.7 Hz, 1H), 3.80 (s, 2H), 3.29 (dt, 3J=6.0 Hz, 4J=1.7 Hz, 2H), 1.60 (s, broad,

13 1 1H); C{ H} NMR (CDCl3, 600 MHz): 140.3, 136.8, 128.5, 128.3, 127.1, 116.2, 53.4,

+ 51.9; HRMS (ESI) (m/z): [M+H] calc for C10H14N, 148.1126; found, 148.1120.

N-(4-Iodobenzyl)prop-2-en-1-amine (17b): Colorless oily liquid (121 mg, 89% isolated

1 3 3 yield), H NMR (CDCl3, 400 MHz): 7.64 (d, J=8.0 Hz, 2H), 7.08 (d, J=8.0 Hz, 2H),

5.91 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.18 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz,

1H), 5.11 (dq, 3J=10.4 Hz, 4J=2J=1.6 Hz, 1H), 3.73 (s, 2H), 3.25 (dt, 3J=6.0 Hz, 4J=1.6

13 1 Hz, 2H), 1.43 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz): 140.0, 137.5, 136.7,

+ 130.3, 116.3, 92.3, 52.7, 51.8; HRMS (ESI) (m/z): [M+H] calc for C10H13IN, 274.0093; found, 274.0103.

N-(2-Bromobenzyl)prop-2-en-1-amine (17c):334 Colorless oily liquid (89 mg, 79%

1 3 3 isolated yield), H NMR (CDCl3, 600 MHz): 7.54 (d, J=7.8 Hz, 1H), 7.39 (dd, J=7.2

Hz, 4J=1.2 Hz, 1H), 7.28 (t, 3J=7.8 Hz, 1H), 7.13 (td, 3J=7.2 Hz, 4J=1.2 Hz, 1H), 5.98-

5.91 (m, 1H), 5.22 (dm, 3J=17.4 Hz, 1H), 5.13 (dm, 3J=10.2 Hz, 1H), 3.87 (s, 2H), 3.28 145

3 13 1 (dm, J=6.0 Hz, 2H), 1.83 (broad s, 1H); C{ H} NMR (CDCl3, 600 MHz): 139.0, 136.5,

133.0, 130.6, 128.8, 127.6, 124.2, 116.6, 53.1, 51.6; HRMS (ESI) (m/z): [M+H]+ calc for

C10H13BrN, 226.0231; found, 226.0230.

N-(3-Bromobenzyl)prop-2-en-1-amine (17d):335 Colorless oily liquid (101 mg, 76%

1 3 isolated yield), H NMR (CDCl3, 600 MHz): 7.50 (s, 1H), 7.38 (d, J=7.2 Hz, 1H), 7.25

(d, 3J=7.2 Hz, 1H), 7.19 (t, 3J=7.2 Hz, 1H), 5.92 (ddt, 3J=17.2 Hz, 3J=10.2 Hz, 3J=5.8 Hz,

1H), 5.20 (dq, 3J=17.2 Hz, 4J=2J=1.8 Hz, 1H), 5.13 (dq, 3J=10.2 Hz, 4J=2J=1.8 Hz, 1H),

3.76 (s, 2H), 3.26 (dt, 3J=5.8 Hz, 4J=1.8 Hz, 2H), 1.37 (broad s, 1H); 13C{1H} NMR

(CDCl3, 600 MHz): 142.8, 136.7, 131.3, 130.2, 130.1, 126.9, 122.7, 116.4, 52.7, 51.8;

+ HRMS (ESI) (m/z): [M+H] calc for C10H13BrN, 226.0231; found, 226.0227.

N-(2-Chlorobenzyl)prop-2-en-1-amine (17e):336 Colorless oily liquid (74 mg, 82%

1 isolated yield), H NMR (CDCl3, 600 MHz): 7.39-7.35 (m, 2H), 7.25-7.19 (m, 2H), 5.94

(ddt, 3J=17.2 Hz, 3J=10.2 Hz, 3J=5.8 Hz, 1H), 5.21 (dq, 3J=17.2 Hz, 4J=2J=1.8 Hz, 1H),

5.13 (dq, 3J=10.2 Hz, 4J=2J=1.8 Hz, 1H), 3.89 (s, 2H), 3.28 (dt, 3J=5.8 Hz, 4J=1.8 Hz,

13 1 2H), 1.59 (broad s, 1H); C{ H} NMR (CDCl3, 600 MHz): 137.7, 136.8, 133.9, 130.4,

+ 129.7, 128.5, 126.9, 116.3, 51.8, 50.8; HRMS (ESI) (m/z): [M+H] calc for C10H13ClN,

182.0737; found, 182.0736.

146

N-(3-Chlorobenzyl)prop-2-en-1-amine (17f):335 Colorless oily liquid (76 mg, 84%

1 isolated yield), H NMR (CDCl3, 400 MHz): 7.34 (s, 1H), 7.26-7.19 (m, 3H), 5.97-5.87

(m, 1H), 5.20 (dm, 3J=17.4 Hz, 1H), 5.13 (dm, 3J=10.2 Hz, 1H), 3.77 (s, 2H), 3.26 (dm,

3 13 1 J=6.0 Hz, 2H), 1.43 (broad s, 1H); C{ H} NMR (CDCl3, 600 MHz): 142.5, 136.7,

134.4, 129.7, 128.4, 127.2, 126.4, 116.3, 52.7, 51.8; HRMS (ESI) (m/z): [M+H]+ calc for

C10H13ClN, 182.0737; found, 182.0731.

N-(4-Chlorobenzyl)prop-2-en-1-amine (17g):321 Colorless oily liquid (84 mg, 92%

1 3 isolated yield), H NMR (CDCl3, 400 MHz): 7.30-7.24 (m, 4H), 5.91 (ddt, J=17.2 Hz,

3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.19 (dm, 3J=17.2 Hz, 1H), 5.12 (dm, 3J=10.4 Hz, 1H), 3.76

3 13 1 (s, 2H), 3.25 (dm, J=6.0 Hz, 2H), 1.40 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz):

138.9, 136.7, 132.7, 129.6, 128.6, 116.3, 52.6, 51.8; HRMS (ESI) (m/z): [M+H]+ calc for

C10H13ClN, 182.0737; found, 182.0739.

N-(4-Fluorobenzyl)prop-2-en-1-amine (17h):337 Colorless oily liquid (74 mg, 90%

1 isolated yield), H NMR (CDCl3, 400 MHz): 7.30-7.26 (m, 2H), 7.03-6.97 (m, 2H), 5.92

(ddt, 3J=17.2 Hz, 3J=10.0 Hz, 3J=6.0 Hz, 1H), 5.19 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz, 1H),

5.11 (dq, 3J=10.0 Hz, 4J=2J=1.6 Hz, 1H), 3.75 (s, 2H), 3.26 (dt, 3J=6.0 Hz, 4J=1.6 Hz,

13 1 1 2H), 1.39 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz): 162.0 (d, JC-F=244.0 Hz),

147

4 3 2 136.8, 136.1 (d, JC-F=2.9 Hz), 129.8 (d, JC-F=7.8 Hz), 116.2, 115.2 (d, JC-F=21.5 Hz),

19 1 + 52.6, 51.8; F{ H} NMR (CDCl3, 400 MHz): -116.49; HRMS (ESI) (m/z): [M+H] calc for C10H13FN, 166.1032; found, 166.1040.

N-(4-Methylbenzyl)prop-2-en-1-amine (17i): Colorless liquid (70 mg, 84% isolated

1 3 3 yield), H NMR (CDCl3, 600 MHz): 7.21 (d, J=7.9 Hz, 2H), 7.14 (d, J=7.9 Hz, 2H),

5.96-5.90 (m, 1H), 5.19 (dm, 3J=17.2 Hz, 1H), 5.11 (dm, 3J=10.2 Hz, 1H), 3.76 (s, 2H),

3.27 (dt, 3J=5.9 Hz, 4J=1.4 Hz, 2H), 2.33 (s, 3H), 1.52 (broad s, 1H); 13C{1H} NMR

(CDCl3, 600 MHz): 137.3, 136.9, 136.6, 129.2, 128.3, 116.1, 53.1, 51.8, 21.2; HRMS

+ (ESI) (m/z): [M+H] calc for C11H16N, 162.1283; found, 162.1288.

N-(4-Methoxybenzyl)prop-2-en-1-amine (17j):338 Colorless oily liquid (67 mg, 76%

1 3 3 isolated yield), H NMR (CDCl3, 400 MHz): 7.24 (d, J=8.8 Hz, 2H), 6.91 (d, J=8.8 Hz,

2H), 5.97 (ddt, 3J=17.2 Hz, 3J=10.2 Hz, 3J=5.8 Hz, 1H), 5.23 (dq, 3J=17.2 Hz, 4J=2J=1.8

Hz, 1H), 5.16 (dq, 3J=10.2 Hz, 4J=2J=1.8 Hz, 1H), 3.85 (s, 3H), 3.77 (s, 2H), 3.31 (dt,

3 4 13 1 J=5.8 Hz, J=1.8 Hz, 2H), 1.52 (broad s, 1H); C{ H} NMR (CDCl3, 600 MHz): 158.7,

137.0, 132.6, 129.5, 116.1, 113.9, 55.4, 52.8, 51.9; HRMS (ESI) (m/z): [M+H]+ calc for

C11H16NO, 178.1232; found, 178.1238.

148

4-((Allylamino)methyl)-N,N-dimethylaniline (17k): Colorless oily liquid (87 mg, 91%

1 3 3 isolated yield), H NMR (CDCl3, 400 MHz): 7.20 (dm, J=8.8 Hz, 2H), 6.72 (dm, J=8.8

Hz, 2H), 5.94 (ddt, 3J=16.8 Hz, 3J=10.0 Hz, 3J=6.0 Hz, 1H), 5.19 (dq, 3J=16.8 Hz,

4J=2J=1.6 Hz, 1H), 5.11 (dq, 3J=10.0 Hz, 4J=2J=1.6 Hz, 1H), 3.70 (s, 2H), 3.27 (dt, 3J=6.0

4 13 1 Hz, J=1.6 Hz, 2H), 2.94 (s, 6H), 1.42 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz):

149.9, 137.1, 129.2, 128.4, 115.9, 112.8, 52.9, 51.8, 40.9; HRMS (ESI) (m/z): [M+H]+ calc for C12H19N2, 191.1548; found, 191.1557.

N-(4-Nitrobenzyl)prop-2-en-1-amine (17l):336 Pale yellow oily liquid (75 mg, 78%

1 3 3 isolated yield), H NMR (CDCl3, 400 MHz): 8.18 (d, J=8.4 Hz, 2H), 7.51 (d, J=8.4 Hz,

2H), 5.91 (ddt, 3J=17.6 Hz, 3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.20 (dq, 3J=17.6 Hz, 4J=2J=1.6

Hz, 1H), 5.14 (dq, 3J=10.4 Hz, 4J=2J=1.6 Hz, 1H), 3.90 (s, 2H), 3.28 (dt, 3J=6.0 Hz,

4 13 1 J=1.6 Hz, 2H), 1.50 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz): 148.4, 136.5,

+ 128.9, 123.9, 116.7, 52.6, 52.0; HRMS (ESI) (m/z): [M+H] calc for C10H13N2O2,

193.0977; found, 193.0975.

N-(3,4,5-Trimethoxybenzyl)prop-2-en-1-amine (17m): Colorless oily liquid (106 mg,

1 3 89% isolated yield), H NMR (CDCl3, 400 MHz): 6.56 (s, 2H), 5.94 (ddt, J=17.2 Hz,

149

3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.21 (dm, 3J=17.2 Hz, 1H), 5.12 (dm, 3J=10.4 Hz, 1H), 3.86

(s, 6H), 3.83 (s, 3H), 3.73 (s, 2H), 3.29 (dm, 3J=6.0 Hz, 2H), 1.48 (broad s, 1H); 13C{1H}

NMR (CDCl3, 400 MHz): 153.3, 136.8, 136.2, 116.3, 105.0, 61.0, 56.2, 53.7, 52.0;

+ HRMS (ESI) (m/z): [M+H] calc for C13H20NO3, 238.1443; found, 238.1447.

N-(3-(Trifluoromethyl)benzyl)prop-2-en-1-amine (17n): Colorless oily liquid (99 mg,

1 92% isolated yield), H NMR (CDCl3, 600 MHz): 7.61 (s, 1H), 7.53-7.50 (m, 2H), 7.45-

7.42 (m, 1H), 5.93 (ddt, 3J=16.4 Hz, 3J=10.2 Hz, 3J=6.0 Hz, 1H), 5.21 (dq, 3J=16.4 Hz,

4J=2J=1.6 Hz, 1H), 5.13 (dq, 3J=10.2 Hz, 4J=2J=1.6 Hz, 1H), 3.85 (s, 2H), 3.28 (dt, 3J=6.0

4 13 1 Hz, J=1.6 Hz, 2H), 1.43 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz): 141.4, 136.6,

2 3 1 131.6, 130.8 (q, JC-F=32.3 Hz), 128.9, 125.0 (q, JC-F=3.5 Hz), 124.3 (q, JC-F=271.8 Hz),

3 19 1 123.9 (q, JC-F=3.8 Hz), 116.4, 52.8, 51.9; F{ H} NMR (CDCl3, 400 MHz): -62.96;

+ HRMS (ESI) (m/z): [M+H] calc for C11H13F3N, 216.1000; found, 216.0998.

4-((Allylamino)methyl)benzonitrile (17o):336 Colorless oily liquid (75 mg, 83% isolated

1 3 3 yield), H NMR (CDCl3, 400 MHz): 7.61 (d, J=8.4 Hz, 2H), 7.45 (d, J=8.4 Hz, 2H),

5.90 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.19 (dq, 3J=17.2 Hz, 4J=2J=1.6 Hz,

1H), 5.13 (dq, 3J=10.4 Hz, 4J=2J=1.6 Hz, 1H), 3.85 (s, 2H), 3.26 (dt, 3J=6.0 Hz, 4J=1.6

13 1 Hz, 2H), 1.44 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz): 146.1, 136.4, 132.3,

+ 128.8, 119.1, 116.5, 110.8, 52.7, 51.9; HRMS (ESI) (m/z): [M+H] calc for C11H13N2,

173.1079; found, 173.1087.

150

3-((Allylamino)methyl)benzonitrile (17p):335 Colorless oily liquid (76 mg, 88% isolated

1 3 yield), H NMR (CDCl3, 400 MHz): 7.66 (s, 1H), 7.59-7.53 (m, 2H), 7.42 (t, J=7.6 Hz,

1H), 5.91 (ddt, 3J=17.2 Hz, 3J=10.2 Hz, 3J=5.8 Hz, 1H), 5.20 (dq, 3J=17.2 Hz, 4J=2J=1.6

Hz, 1H), 5.14 (dq, 3J=10.2 Hz, 4J=2J=1.6 Hz, 1H), 3.83 (s, 2H), 3.27 (dt, 3J=5.8 Hz,

4 13 1 J=1.6 H, 2H), 1.46 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz): 142.0, 136.5,

132.7, 131.8, 130.8, 129.3, 119.1, 116.6, 112.5, 52.4, 51.9; HRMS (ESI) (m/z): [M+H]+ calc for C11H13N2, 173.1079; found, 173.1084.

N-2-Propen-1-yl-1,3-benzodioxole-5-methanamine (17r):339 Colorless liquid (80 mg,

1 79% isolated yield), H NMR (CDCl3, 600 MHz): 6.83 (s, 1H), 6.75 (s, 2H), 5.94-5.88

(m, 1H), 5.93 (s, 2H), 5.18 (dq, 3J=17.2 Hz, 4J=2J=1.7 Hz, 1H), 5.10 (dq, 3J=10.3 Hz,

4J=2J=1.7 Hz, 1H), 3.69 (s, 2H), 3.25 (dt, 3J=6.0 Hz, 4J=1.7 Hz, 2H), 1.43 (broad s, 1H);

13 1 C{ H} NMR (CDCl3, 600 MHz): 147.8, 146.6, 136.9, 134.4, 121.4, 116.1, 108.9,

+ 108.2, 101.0, 53.2, 51.7; HRMS (ESI) (m/z): [M+H] calc for C11H14NO2, 192.1025; found, 192.1032.

N-(Furan-2-ylmethyl)prop-2-en-1-amine (17s):340 Colorless liquid (55 mg, 81%

1 isolated yield), H NMR (CDCl3, 600 MHz): 7.36-7.35 (m, 1H), 6.31-6.30 (m, 1H), 6.17

(d, 3J=3.2 Hz, 1H), 5.90 (ddt, 3J=16.8 Hz, 3J=10.2 Hz, 3J=6.6 Hz, 1H), 5.19 (dm, 3J=16.8

Hz, 1H), 5.11 (dm, 3J=10.2 Hz, 1H), 3.78 (s, 2H), 3.25 (dm, 3J=6.6 Hz, 2H), 1.57 (broad 151

13 1 s, 1H); C{ H} NMR (CDCl3, 600 MHz): 153.9, 141.9, 136.6, 116.4, 110.2, 107.1, 51.6,

+ 45.5; HRMS (ESI) (m/z): [M+H] calc for C8H12NO, 138.0919; found, 138.0907.

N-(Naphthalen-2-ylmethyl)prop-2-en-1-amine (17t):339 White solid (88 mg, 89%

1 isolated yield), H NMR (CDCl3, 400 MHz): 7.85-7.81 (m, 3H), 7.78 (s, 1H), 7.50-7.45

(m, 3H), 5.97 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.23 (dm, 3J=17.2 Hz, 1H),

5.15 (dm, 3J=10.4 Hz, 1H), 3.97 (s, 2H), 3.33 (dm, 3J=6.0 Hz, 2H), 1.52 (broad s, 1H);

13 1 C{ H} NMR (CDCl3, 400 MHz): 137.9, 136.9, 133.5, 132.7, 128.2, 127.81, 127.76,

126.7, 126.6, 126.1, 125.7, 116.2, 53.5, 51.9; HRMS (ESI) (m/z): [M+H]+ calc for

C14H16N, 198.1283; found, 198.1285.

N-(Naphthalen-1-ylmethyl)prop-2-en-1-amine (17u):341 Colorless oily liquid (86 mg,

1 3 3 87% isolated yield), H NMR (CDCl3, 400 MHz): 8.13 (d, J=8.0 Hz, 1H), 7.87 (d, J=8.0

Hz, 1H), 7.78 (d, 3J=8.0 Hz, 1H), 7.56-7.41 (m, 4H), 6.00 (ddt, 3J=17.2 Hz, 3J=10.2 Hz,

3J=6.2 Hz, 1H), 5.25 (dq, 3J=17.2 Hz, 4J=2J=1.8 Hz, 1H), 5.16 (dq, 3J=10.2 Hz, 4J=2J=1.8

Hz, 1H), 4.24 (s, 2H), 3.40 (dt, 3J=6.2 Hz, 4J=1.8 Hz, 2H), 1.50 (broad s, 1H); 13C{1H}

NMR (CDCl3, 400 MHz): 137.0, 136.0, 134.0, 131.9, 128.8, 127.9, 126.24, 126.20,

+ 125.7, 125.5, 123.8, 116.4, 52.5, 51.0; HRMS (ESI) (m/z): [M+H] calc for C14H16N,

198.1283; found, 198.1288.

152

N-Allyl-1-(ferrocenyl)methanamine (17v):342 Red oily liquid (107 mg, 84% isolated

1 3 yield), H NMR (CDCl3, 400 MHz): 5.97-5.87 (m, 1H), 5.19 (dm, J=16.8 Hz, 1H), 5.11

(dm, 3J=10.4 Hz, 1H), 4.19 (t, J=2.0 Hz, 2H), 4.12 (s, 5H), 4.11 (t, J=2.0 Hz, 2H), 3.51 (s,

3 13 1 2H), 3.28 (dm, J=6.0 Hz, 2H), 1.44 (broad s, 1H); C{ H} NMR (CDCl3, 400 MHz):

137.0, 116.1, 86.9, 68.54, 68.51, 67.9, 52.1, 48.4; HRMS (ESI) (m/z): [M+H]+ calc for

C14H18FeN, 256.0789; found, 256.0793.

N-(1-Phenylethyl)prop-2-en-1-amine (17w):343 Pale yellow oily liquid (55 mg, 68%

1 isolated yield), H NMR (CDCl3, 600 MHz): 7.34-7.31 (m, 4H), 7.26-7.23 (m, 1H), 5.89

(ddt, 3J=16.8 Hz, 3J=10.2 Hz, 3J=6.0 Hz, 1H), 5.13 (dq, 3J=16.8 Hz, 4J=2J=1.8 Hz, 1H),

5.07 (dq, 3J=10.2 Hz, 4J=2J=1.8 Hz, 1H), 3.80 (q, 3J=6.6 Hz, 1H), 3.10 (dm, 3J=6.0 Hz,

3 13 1 2H), 1.37 (d, J=6.6 Hz, 3H), 1.35 (broad s, 1H); C{ H} NMR (CDCl3, 600 MHz):

145.6, 137.1, 128.6, 127.0, 126.7, 115.8, 57.7, 50.4, 24.4; HRMS (ESI) (m/z): [M+H]+ calc for C11H16N, 162.1283; found, 162.1284.

N-(1-(4-Methoxyphenyl)ethyl)prop-2-en-1-amine (17x):343 Colorless oily liquid (51

1 3 mg, 53% isolated yield), H NMR (CDCl3, 400 MHz): 7.23 (dm, J=13.2 Hz, 2H), 6.87

153

(dm, 3J=13.2 Hz, 2H), 5.88 (ddt, 3J=17.2 Hz, 3J=10.4 Hz, 3J=6.0 Hz, 1H), 5.12 (dm,

3J=17.2 Hz, 1H), 5.06 (dm, 3J=10.4 Hz, 1H), 3.80 (s, 3H), 3.76 (q, 3J=6.4 Hz, 1H), 3.09

3 3 13 1 (dm, J=6.0 Hz, 2H), 1.36 (broad s, 1H), 1.34 (d, J=6.4 Hz, 3H); C{ H} NMR (CDCl3,

400 MHz): 158.6, 137.6, 137.1, 127.7, 115.8, 113.9, 57.0, 55.4, 50.3, 24.4; HRMS (ESI)

+ (m/z): [M+H] calc for C12H18NO, 192.1388; found, 192.1385.

1 Methyl 2-(phenylsilyl)acrylate (18a): 86% isolated yield (83 mg), H NMR (CDCl3,

400 MHz): 7.64-7.61 (m, 2H), 7.44-7.37 (m, 3H), 7.03 (d, 2J=2.0 Hz, 1H), 6.26 (d, 2J=2.0

13 1 Hz, 1H), 4.69 (s, 2H), 3.76 (s, 3H); C{ H} NMR (CDCl3, 400 MHz): 168.5, 144.6,

+ 137.2, 135.7, 130.5, 130.2, 128.2, 52.1; HRMS (EI) (m/z): [M-H] calc for C10H11O2Si,

191.0528; found, 191.0530.

1 Methyl 2-(diphenylsilyl)acrylate (18b): 91% isolated yield (122 mg), H NMR (CDCl3,

400 MHz): 7.66-7.63 (m, 4H), 7.47-7.41 (m, 6H), 7.15 (d, 2J=2.8 Hz, 1H), 6.25 (d, 2J=2.8

13 1 Hz, 1H), 5.31 (s, 1H), 3.73 (s, 3H); C{ H} NMR (CDCl3, 400 MHz): 168.9, 145.0,

+ 138.9, 135.7, 132.4, 130.1, 128.2, 52.0; HRMS (EI) (m/z): [M-H] calc for C16H15O2Si,

267.0841; found, 267.0841.

154

Methyl 2-(methyl(phenyl)silyl)acrylate (18c): 80% isolated yield (83 mg), 1H NMR

2 (CDCl3, 400 MHz): 7.60-7.58 (m, 2H), 7.42-7.37 (m, 3H), 6.96 (d, J=2.8 Hz, 1H), 6.16

(d, 2J=2.8 Hz, 1H), 4.72 (q, 3J= 4.0 Hz, 1H), 3.75 (s, 3H), 0.57 (d, 3J=4.0 Hz, 3H);

13 1 C{ H} NMR (CDCl3, 400 MHz): 169.0, 142.9, 140.3, 134.8, 133.5, 129.8, 128.0, 51.9,

+ -5.3; HRMS (EI) (m/z): [M-H] calc for C11H13O2Si, 205.0685; found, 205.0684.

Methyl 2-(diisopropylsilyl)acrylate (18d): 64% isolated yield (64 mg), 1H NMR

2 2 (CDCl3, 600 MHz): 6.92 (d, J=3.6 Hz, 1H), 6.17 (d, J=3.6 Hz, 1H), 3.75 (s, 3H), 3.65 (t,

3J=3.6 Hz, 1H), 1.20-1.15 (m, 2H), 1.05 (d, 3J=7.2 Hz, 6H), 0.98 (d, 3J=7.2 Hz, 6H);

13 1 C{ H} NMR (CDCl3, 600 MHz): 169.6, 143.3, 139.0, 51.8, 18.9, 18.8, 10.7; HRMS

+ (CI) (m/z): [M+H] calc for C10H21O2Si, 201.1311; found, 201.1313.

Methyl (E)-2-(phenylsilyl)hex-2-enoate (18e): 93% isolated yield (109 mg), 1H NMR

3 (CDCl3, 400 MHz): 7.62-7.60 (m, 2H), 7.42-7.36 (m, 3H), 6.68 (t, J=6.8 Hz, 1H), 4.66

(s, 2H), 3.70 (s, 3H), 2.62 (q, 3J=6.8 Hz, 2H), 1.53-1.47 (m, 2H), 0.95 (t, 3J=7.2 Hz, 3H);

13 1 C{ H} NMR (CDCl3, 400 MHz): 168.7, 162.9, 135.6, 131.5, 129.9, 128.1, 127.5, 51.4,

155

+ 33.9, 22.2, 13.9; HRMS (EI) (m/z): [M-H] calc for C13H17O2Si, 233.0998; found,

233.0990.

Methyl (E)-2-(diphenylsilyl)hex-2-enoate (18f): 88% isolated yield (137 mg), 1H NMR

3 (CDCl3, 400 MHz): 7.64-7.62 (m, 4H), 7.45-7.39 (m, 6H), 6.60 (t, J=7.2 Hz, 1H), 5.23

(s, 1H), 3.63 (s, 3H), 2.62 (q, 3J=7.2 Hz, 2H), 1.55-1.49 (m, 2H), 0.97 (t, 3J=7.2 Hz, 3H);

13 1 C{ H} NMR (CDCl3, 400 MHz): 169.3, 161.7, 135.6, 133.1, 129.9, 129.5, 128.0, 51.3,

+ 33.9, 22.3, 13.9; HRMS (EI) (m/z): [M-H] calc for C19H21O2Si, 309.1311; found,

309.1306.

Methyl (E)-2-(methyl(phenyl)silyl)hex-2-enoate (18g): 85% isolated yield (106 mg),

1 3 H NMR (CDCl3, 400 MHz): 7.60-7.57 (m, 2H), 7.41-7.38 (m, 3H), 6.52 (t, J= 7.2 Hz,

1H), 4.67 (q, 3J=4.0 Hz, 1H), 3.69 (s, 3H), 2.54 (q, 3J= 7.2 Hz, 2H), 1.49 (sext, 3J=7.2 Hz,

3 3 13 1 2H), 0.95 (t, J=7.2 Hz, 3H), 0.54 (d, J=4.0 Hz, 3H); C{ H} NMR (CDCl3, 400 MHz):

169.5, 159.2, 134.9, 134.7, 131.0, 129.6, 127.9, 51.2, 33.8, 22.3, 13.9, -5.0; HRMS (EI)

+ (m/z): [M-H] calc for C14H19O2Si, 247.1154; found, 247.1153.

156

Methyl (E)-2-(diisopropylsilyl)hex-2-enoate (18h): 83% isolated yield (101 mg). 1H

3 3 NMR (CDCl3, 400 MHz): 6.38 (t, J=7.6 Hz, 1H), 3.68 (s, 3H), 3.56 (t, J=3.2 Hz, 1H),

2.42 (q, 3J=7.6 Hz, 2H), 1.50-1.41 (m, 2H), 1.13-1.05 (m, 2H), 1.01 (d, 3J=6.8 Hz, 6H),

3 3 13 1 0.97 (d, J=6.8 Hz, 6H), 0.90 (t, J=7.6 Hz, 3H); C{ H} NMR (CDCl3, 400 MHz):

170.4, 158.1, 129.9, 51.1, 33.8, 22.4, 18.8, 18.7, 13.8, 11.0. HRMS (EI) (m/z): [M-H]+ calc for C13H25O2Si, 241.1624; found, 241.1624.

Methyl (E)-2-(diphenylsilyl)-3-phenylacrylate (18j): 93% isolated yield (160 mg), 1H

NMR (CDCl3, 600 MHz): 7.69-7.68 (m, 4H), 7.48-7.45 (m, 2H), 7.43-7.41 (m, 4H),

13 1 7.38-7.32 (m, 5H), 7.10 (s, 1H), 5.34 (s, 1H), 3.58 (s, 3H); C{ H} NMR (CDCl3, 600

MHz): 171.2, 148.8, 136.2, 135.8, 132.0, 131.7, 130.3, 129.3, 128.7, 128.5, 128.2, 51.8;

+ HRMS (EI) (m/z): [M] calc for C22H20O2Si, 344.1233; found, 344.1238.

Methyl (E)-2-(methyl(phenyl)silyl)-3-phenylacrylate (18k): 79% isolated yield (112

1 mg), H NMR (CDCl3, 400 MHz): 7.66-7.64 (m, 2H), 7.44-7.31 (m, 8H), 7.03 (s, 1H),

3 3 13 1 4.81 (q, J=3.6 Hz, 1H), 3.67 (s, 3H), 2.62 (d, J=3.6 Hz, 3H); C{ H} NMR (CDCl3,

157

400 MHz): 171.5, 146.6, 136.3, 134.9, 133.4, 130.8, 130.1, 129.0, 128.53, 128.50, 128.2,

+ 51.8, -5.3; HRMS (EI) (m/z): [M] calc for C17H18O2Si, 282.1076; found, 282.1079.

Methyl (E)-2-(diisopropylsilyl)-3-phenylacrylate (18l): 68% isolated yield (94 mg), 1H

NMR (CDCl3, 600 MHz): 7.33-7.24 (m, 5H), 7.05 (s, 1H), 3.77-3.75 (m, 1H), 3.69 (s,

3H), 1.24-1.19 (m, 2H), 1.12 (d, 3J=7.6 Hz, 6H), 1.10 (d, 3J=7.6 Hz, 6H); 13C{1H} NMR

(CDCl3, 600 MHz): 172.3, 158.8, 146.4, 136.5, 128.8, 128.5, 128.4, 51.7, 18.61, 18.56,

+ 11.1; HRMS (EI) (m/z): [M-H] calc for C16H23O2Si, 275.1467; found, 275.1471.

(3-Methylbuta-1,3-dien-1-yl)diphenylsilane (18m): 92% isolated yield (115 mg), 1H

4 NMR (CDCl3, 400 MHz): 7.60-7.58 (m, 4H), 7.43-7.37 (m, 6H), 6.83 (d, J=18.8 Hz,

1H), 6.09 (dd, 4J=18.8 Hz, 2J=3.2 Hz, 1H), 5.17 (d, 2J=3.2 Hz, 1H), 5.14 (s, 1H), 5.06 (s,

13 1 1H), 1.92 (s, 3H); C{ H} NMR (CDCl3, 400 MHz): 152.1, 143.3, 135.6, 133.9, 129.8,

+ 128.2, 121.4, 119.0, 18.1; HRMS (EI) (m/z): [M] calc for C17H18Si, 250.1178; found,

250.1172.

(E)-(2-Methylhexa-1,3-dien-3-yl)diphenylsilane (18n): (same regio- and stereoisomers

1 from either 15a or 4a) 81% isolated yield (113 mg), H NMR (CDCl3, 600 MHz): 7.60

158

(dd, 3J=7.8 Hz, 4J=1.4 Hz, 4H), 7.42-7.26 (m, 6H), 5.89 (t, 3J=7.1 Hz, 1H), 5.09 (s, 1H),

4.86 (d, 2J=1.3 Hz, 1H), 4.53 (d, 3J=1.3 Hz, 1H), 2.20 (quint, 3J=7.1 Hz, 2H), 1.71 (s,

3 13 1 3H), 0.99 (t, J=7.1 Hz, 3H); C{ H} NMR (CDCl3, 600 MHz): 147.5, 145.4, 139.2,

135.9, 133.9, 129.7, 128.0, 112.2, 24.5, 23.8, 14.4; HRMS (EI) (m/z): [M]+ calc for

C19H22Si, 278.1491; found, 278.1491.

1 Diphenyl(1-phenylethoxy)silane (19a): 94% isolated yield (143 mg), H NMR (CDCl3,

400 MHz): 7.71 (dd, 3J=7.6 Hz, 4J=1.6 Hz, 2H), 7.66 (d, 3J=2.0 Hz, 2H), 7.52-7.36 (m,

11H), 5.51 (s, 1H), 5.09 (q, 3J=6.4 Hz, 1H), 1.60 (d, 3J=6.4 Hz, 3H); 13C{1H} NMR

(CDCl3, 400 MHz): 145.4, 134.83, 134.79, 134.4, 134.3, 130.5, 130.4, 128.4, 128.13,

128.06, 127.3, 125.7, 72.8, 26.4.344

Diphenyl(1-phenylpropoxy)silane (19b): 85% isolated yield (135 mg), 1H NMR

3 (CDCl3, 400 MHz): 7.71-7.62 (m, 4H), 7.51-7.36 (m, 11H), 5.47 (s, 1H), 4.81 (t, J=6.0

Hz, 1H), 2.01-1.91 (m, 1H), 1.91-1.82 (m, 1H), 0.96 (t, 3J=7.2 Hz, 3H); 13C{1H} NMR

(CDCl3, 400 MHz): 143.9, 135.9, 135.8, 134.9, 134.8, 134.4, 134.2, 130.4, 130.3, 130.0,

129.9, 128.2, 128.1, 128.0, 127.3, 126.4, 78.2, 32.9, 10.1.

159

1 Diphenyl(1-(p-tolyl)ethoxy)silane (19c): 71% isolated yield (113 mg), H NMR (CDCl3,

400 MHz): 7.72 (d, 3J=7.6 Hz, 2H), 7.67 (d, 3J=7.2 Hz, 2H), 7.52-7.41 (m, 6H), 7.33 (d,

3J=8.0 Hz, 2H), 7.21 (d, 3J=8.0 Hz, 2H), 5.51 (s, 1H), 5.07 (q, 3J=6.0 Hz, 1H), 2.42 (s,

3 13 1 3H), 1.59 (d, J=6.0 Hz, 3H); C{ H} NMR (CDCl3, 400 MHz): 142.4, 136.8, 135.9,

134.83, 134.79, 134.4, 130.41, 130.36, 129.0, 128.1, 128.0, 125.6, 72.7, 26.4, 21.4.

(1-(4-Methoxyphenyl)ethoxy)diphenylsilane (19d): 86% isolated yield (144 mg), 1H

3 4 3 NMR (CDCl3, 400 MHz): 7.63 (dd, J=8.0 Hz, J=1.6 Hz, 2H), 7.57 (dd, J=8.0 Hz,

4J=1.6 Hz, 2H), 7.46-7.33 (m, 6H), 7.26 (d, 3J=8.8 Hz, 2H), 6.85 (d, 3J=8.8 Hz, 2H), 5.39

(s, 1H), 4.97 (q, 3J=6.4 Hz, 1H), 3.81 (s, 3H), 1.50 (d, 3J=6.4 Hz, 3H); 13C{1H} NMR

(CDCl3, 400 MHz): 158.8, 137.6, 134.84, 134.79, 134.4, 134.3, 130.4, 130.3, 128.1,

128.0, 127.0, 113.7, 72.5, 55.4, 26.3.

(1-(4-Chlorophenyl)ethoxy)diphenylsilane (19e): 66% isolated yield (112 mg), 1H

3 4 3 NMR (CDCl3, 400 MHz): 7.62 (dd, J=8.0 Hz, J=1.6 Hz, 2H), 7.57 (dd, J=8.0 Hz,

4J=1.6 Hz, 2H), 7.46-7.33 (m, 6H), 7.27 (s, 4H), 5.40 (s, 1H), 4.96 (q, 3J=6.4 Hz, 1H),

160

3 13 1 1.48 (d, J=6.4 Hz, 3H); C{ H} NMR (CDCl3, 400 MHz): 143.9, 134.81, 134.76, 134.1,

133.9, 132.9, 130.6, 130.5, 128.5, 128.2, 128.1, 127.1, 72.2, 26.4.

(1-(2-Methoxyphenyl)ethoxy)diphenylsilane (19g): 77% isolated yield (129 mg), 1H

3 4 3 NMR (CDCl3, 400 MHz): 7.64 (dd, J=8.0 Hz, J=1.6 Hz, 2H), 7.59 (dd, J=8.0 Hz,

4J=1.6 Hz, 2H), 7.45-7.34 (m, 6H), 7.23 (t, 3J=8.4 Hz, 1H), 6.93-6.90 (m, 2H), 6.79 (dm,

3J=8.4 Hz, 1H), 5.42 (s, 1H), 4.99 (q, 3J=6.4 Hz, 1H), 3.77 (s, 3H), 1.51 (d, 3J=6.4 Hz,

13 1 3H); C{ H} NMR (CDCl3, 400 MHz): 159.7, 147.1, 134.84, 134.82, 134.3, 134.1,

130.5, 130.4, 129.4, 128.14, 128.07, 118.1, 112.8, 111.1, 72.7, 55.3, 26.4.

1 (Cyclohexyloxy)diphenylsilane (19i): 89% isolated yield (126 mg), H NMR (CDCl3,

400 MHz): 7.69 (dd, 3J=8.0 Hz, 4J=1.6 Hz, 4H), 7.49-7.41 (m, 6H), 5.53 (s, 1H), 3.90-

3.83 (m, 1H), 1.94-1.91 (m, 2H), 1.81-1.76 (m, 2H), 1.56-1.45 (m, 3H), 1.33-1.24 (m,

13 1 3H); C{ H} NMR (CDCl3, 400 MHz): 134.9, 134.7, 130.3, 128.1, 73.1, 35.4, 25.6,

24.2.

1 (Cyclopentyloxy)diphenylsilane (19j): 82% isolated yield (110 mg), H NMR (CDCl3,

161

600 MHz): 7.65 (dd, 3J=7.1 Hz, 4J=1.2 Hz, 4H), 7.47-7.39 (m, 6H), 5.46 (s, 1H), 4.44

(quint, 3J=4.6 Hz, 1H), 1.81-1.78 (m, 2H), 1.77-1.71 (m, 4H), 1.57-1.51 (m, 2H);

13 1 C{ H} NMR (CDCl3, 600 MHz): 134.8, 134.7, 130.3, 128.1, 76.7, 35.4, 23.2.

1 (Pentan-3-yloxy)diphenylsilane (19k): 76% isolated yield (103 mg), H NMR (CDCl3,

600 MHz): 7.65 (dd, 3J=7.8 Hz, 4J=1.4 Hz, 4H), 7.44-7.38 (m, 6H), 5.49 (s, 1H), 3.70

(quint, 3J=5.8 Hz, 1H), 1.58-1.53 (m, 4H), 0.90 (t, 3J=7.4 Hz, 6H); 13C{1H} NMR

(CDCl3, 600 MHz): 134.8, 134.4, 128.2, 128.0, 77.4, 29.2, 10.0.

1 (Pentan-2-yloxy)diphenylsilane (19l): 83% isolated yield (112 mg), H NMR (CDCl3,

400 MHz): 7.66-7.58 (m, 4H), 7.45-7.35 (m, 6H), 5.46 (s, 1H), 4.01-3.95 (m, 1H), 1.62-

1.55 (m, 1H), 1.47-1.32 (m, 3H), 1.21 (d, 3J=6.0 Hz, 3H), 0.87 (t, 3J=7.2 Hz, 3H);

13 1 C{ H} NMR (CDCl3, 400 MHz): 134.82, 134.79, 130.3, 128.1, 70.9, 41.6, 23.4, 19.0,

14.2.

4-Phenylbutan-2-one (hydrolyzed product of 19m): 79% isolated yield (58 mg), 1H

3 NMR (CDCl3, 400 MHz): 7.31-7.26 (m, 2H), 7.22-7.18 (m, 3H), 2.91 (t, J=7.2 Hz, 2H),

3 13 1 2.77 (t, J=7.2 Hz, 2H), 2.15 (s, 3H); C{ H} NMR (CDCl3, 400 MHz): 208.1, 134.4,

128.6, 128.4, 126.2, 45.3, 30.2, 29.8.

162

1 (E)-Oct-4-en-4-yldiphenylsilane (20a): 84% isolated yield (124 mg), H NMR (CDCl3,

400 MHz): 7.57 (d, 3J=6.6 Hz, 4H), 7.41-7.36 (m, 6H), 5.92 (t, 3J=7.2 Hz, 1H), 5.09 (s,

1H), 2.22 (t, 3J=7.8 Hz, 2H), 2.18 (q, 3J=7.2 Hz, 2H), 1.45-1.37 (m, 2H), 1.36-1.30 (m,

3 3 13 1 2H), 0.93 (t, J=7.2 Hz, 3H), 0.84 (t, J=7.2 Hz, 3H); C{ H} NMR (CDCl3, 400 MHz):

146.8, 135.8, 134.4, 129.6, 128.3, 128.0, 32.8, 31.0, 23.2, 22.7, 14.4, 14.1; HRMS (EI)

+ (m/z): [M] calc for C20H26Si, 294.1804; found, 294.1811.

(E)-(1,2-Diphenylvinyl)diphenylsilane (20b): 77% isolated yield (140 mg), 1H NMR

3 4 (CDCl3, 400 MHz): 7.58 (dd, J=7.6 Hz, J=1.6 Hz, 4H), 7.45-7.35 (m, 6H), 7.23-7.16

13 1 (m, 3H), 7.13-7.10 (m, 3H), 7.04-7.00 (m, 5H), 5.30 (s, 1H); C{ H} NMR (CDCl3, 400

MHz): 143.0, 141.7, 140.3, 137.1, 136.0, 133.1, 129.9, 129.8, 128.8, 128.2, 128.14,

+ 128.09, 127.7, 126.3; HRMS (EI) (m/z): [M] calc for C26H22Si, 362.1491; found,

362.1479.

(E)-Diphenyl(1-phenylprop-1-en-1-yl)silane (20c): 80% isolated yield (120 mg), 1H

3 4 NMR (CDCl3, 600 MHz): 7.53 (dd, J=7.8 Hz, J=1.8 Hz, 4H), 7.42-7.39 (m, 2H), 7.36-

163

7.34 (m, 4H), 7.25 (t, 3J=7.8 Hz, 2H), 7.17-7.15 (m, 1H), 7.03 (dd, 3J=7.2 Hz, 4J=1.2 Hz,

2H), 6.31 (q, 3J=6.6 Hz, 1H), 5.21 (s, 1H), 1.74 (d, 3J=6.6 Hz, 3H); 13C{1H} NMR

(CDCl3, 600 MHz): 142.2, 141.2, 139.1, 135.9, 133.7, 129.7, 128.6, 128.2, 128.0, 126.0,

+ 16.5; HRMS (EI) (m/z): [M] calc for C21H20Si, 300.1334; found, 300.1340.

(E)-(2-Butyl-3-methylenehept-1-en-1-yl)diphenylsilane (20e): 86% isolated yield (150

n n 1 mg, 2,3-di butyl/2,4-di butyl isomer : 1/0.27 from crude mixture), H NMR (CDCl3, 600

MHz): 7.56-7.54 (dd, 3J=7.6 Hz, 4J=1.6 Hz, 4H), 7.37-7.33 (m, 6H), 5.64 (d, 3J=5.7 Hz,

1H), 5.14 (d, 3J=5.7 Hz, 1H), 4.80 (d, 2J=2.0 Hz, 1H), 4.77 (d, 2J=2.0 Hz, 1H), 2.28 (t,

3J=7.6 Hz, 2H), 2.05 (t, 3J=7.1 Hz, 2H), 1.44-1.24 (m, 8H), 0.92 (t, 3J=7.3 Hz, 3H), 0.86

3 13 1 (t, J=6.9 Hz, 3H); C{ H} NMR (CDCl3, 600 MHz): 166.3, 150.9, 136.3, 135.1, 128.0,

127.9, 118.1, 113.1, 38.8, 34.6, 30.4, 29.6, 22.8, 22.4, 14.11, 14.08; HRMS (EI) (m/z):

+ [M] calc for C24H32Si, 348.2273; found, 348.2269.

Crystallography: A summary of crystal data and collection parameters for crystal structure of 4a is provided in Table 17. Detailed descriptions of data collection, as well as data solution, are provided below. A suitable crystal was mounted on a polymer loop using Paratone-N hydrocarbon oil. The crystal was transferred to a Apex2 diffractometer with a CCD area detector, centered in the X-ray beam, and cooled to 150 K using a nitrogen-flow low-temperature apparatus that had been previously calibrated by a thermocouple placed at the same position as the crystal. An arbitrary hemisphere of data

164

was collected using 0.3o ω scans, and the data were integrated by the program SAINT.

SHELXTL software package. All non-hydrogen atoms were refined anisotropically. X- ray quality crystals of 4a were grown from a pentane layered tetrahydrofuran solution at room temperature.

165

Table 17. Crystallographic data for compound 4a.

Compound 4a Formula C26H31F3NNiO3PS Formula weight 584.26 Space group Pbca Crystal system Orthorhombic Temperature (K) 150 a (Å) 16.472(2) b (Å) 17.510(2) c (Å) 18.549(2) α (o) 90.00 β (o) 90.00 γ (o) 90.00 V (Å3) 5350.2(9) Z 8 3 Densitycalc (g/cm ) 1.451 Diffractometer Bruker APEX2 Radiation Mo-Kα (λ = 0.71073 Å) Monochromator Graphite Detector CCD detector Scan type, width Ω, 0.3o Scan speed (s) 10 Reflections measured Hemisphere 2θ range (o) 4.04-60.76 Crystal dimensions (mm) 0.42 x 0.21 x 0.18 Reflections measured 82719 Unique reflections 8069 Observations (I > 2σ(I)) 6345 Rint 0.0269 Parameters 325 Robs, Rw, Rall 0.0325, 0.0925, 0.0467 GoF 1.070

5.4 Conclusion

In summary, systems for the catalytic hydrosilylation of imines, ketones and alkynes were studied using cationic complexes of palladium and nickel supported by the

166

3-iminophosphine ancillary ligand. The palladium precatalyst 15a showed satisfactory reactivity in the hydrosilylation of activated aldimines and electron-deficient alkynes.

The mechanism of this system was based on formation of reactive palladium-hydride intermediates formed after treatment of the precatalyst with primary or secondary silanes.

Our previous experiments and time-resolved 1H NMR study in this work provided supporting evidence for this proposed mechanism. On the other hand, the nickel analogue of the palladium catalyst performed regio- and stereoselectively in the hydrosilylation of ketones and internal alkynes with diphenylsilane. Additionally, the nickel precatalyst 4a showed interesting results in ketone hydrosilylation, as well as the 1,4-hydrosilylation of

E-4-phenylbut-3-en-2-one, which contrasts with previous reports on nickel-catalyzed ketone hydrosilylation. Although the mechanism involved in activation of the nickel precatalyst is not fully understood at present, mechanistic investigations and expansion of the substrate scope are ongoing in efforts to unveil details of the precatalyst activation step, as well as the detailed stepwise mechanism of this catalysis.

167

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