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Synthesis and chemistry of phenyl(tTimethylstannyl)diazomethane and lithium phenyldiazomethane

Wheeler, Michael Thurman, Ph.D.

The Ohio State University, 1990

UMI 300 N. Zeeb Rd. Ann Arbor, MI 48106

SYNTHESIS AND CHEMISTRY OF PHENYL(TRIMETHYLSTANNYL)DIAZOMETHANE AND LITHIUM PHENYLDIAZOMETHANE

DISSERTATION

Presented in Partial Fulfillment of the Requirem ents for

the Degree of Doctor of Philosophy in the Graduate

School of the Ohio State University

Michael T. Wheeler, M.S.

The Ohio State University

1990

Dissertation Committee: Approved by

Dr. Harold Shechter

Dr. Anthony Czarnik

Dr. Gideon Fraenkel Adviser Department of Chemistry To My Family

ii ACKNOWLEDGMENTS

I would sincerely like to thank Professor Harold Shechter for his many helpful suggestions and discussions during the course of this research endeavor. I will always remember his absolute dedication to being a Teacher both in the classroom and in the laboratory, I am grateful for having had the opportunity to learn research principles under his direction. Also I would like to thank all of the members of the Shechter Research Group for all the interesting discussions that we have had over the years.

I would like to extend my appreciation to the Ohio State University and the National Science Foundation for their financial support.

Also I would like to thank Wiley Organics of Cochocton, Ohio for their kind donation of several research samples.

ill VITA

1981 ...... B.S., Ohio State University,

The Ohio State University, Columbus, Ohio

1981 -1984 ...... M.S., University of Toledo,

Toledo, Ohio

1984-1987 Teaching Associate,Department of Chemistry,

The Ohio State University, Columbus, Ohio

1987-1990 ...... Research Associate, Department of Chemistry

The Ohio State University, Columbus, Ohio

FIELD OF STUDY

Major Field: Chemistry

iv TABLE OF CONTENTS

DEDICATION...... II

ACKNOWLEDGMENTS...... ill

VITA...... Iv

LIST OF FIGURES...... vll

LIST OF TABLES...... xl

STATEMENT OF PROBLEM...... 1

HISTORICAL Introduction...... •...... 2 Synthesis of a-Metalloldo and a-Metallo DIazo Compounds ...... 3 Chemistry of a-Metalloldo and a-Metallo DIazo Com pounds...... 13

RESULTS AND DISCUSSION Introduction...... 24 Synthesis of Phenyl(trimethylstannyl)dlazomethane (70) ...... 24 Cycloaddition Reactions of 70 ...... 28 Bromlnatlon of 70...... 36 Photolysis and Thermolysis of 70 ...... 38 Rhodlum(ll) Acetate Catalyzed Decomposition Reactions of 70 ...... 44 The Relative Reactivities of Triethylsllane and Ethyl Vinyl Ether Towards 70/Rhodium(ll) Acetate ...... 61 Synthesis and Chemistry of Lithium Phenyldiazomethane (72) ...... 62 SUMMARY...... 75

EXPERIMENTAL...... 78 APPENDICES

A. 1H-NMR and '•^C-NMR Spectra for New Compounds ...... 107

B. Alternative Mechanisms for Diastereoseiectivity of Metai

Catalyzed Decompositions of Diazo Compounds ...... 144

REFERENCES...... 152

vi LIST OF FIGURES

FIGURE PAGE

1 Carbon-tin (p-d)jc Back-bonding In 7 0 ...... 28

2 Nucleophilic Diazo Carbon Attacks ^-Position of Mono-acceptor-substitued Alkene...... 31

3 Possible Geometric Isomers of Azine 118 ...... 40

4 Structure of Rhodium(ll) Acetate...... 45

5 Rhodium(ll) Acetate Ylide ...... 45

6 Insertion of Carbene 71 into a Si-H B o n d ...... 50

7 Insertion of Unsaturated Carbene into a Si-H Bond ...... 50

8 Possible Geometric Isomers of Azines 173 and 174 ...... 73

9 250 MHz 1 H-NMR of Phenyl(trimethylstannyl)diazomethane (70) ...... 108

10 63 MHz 1 3c -NMR of Phenyl(trimethylstannyl)diazomethane (70) ...... 109

11 250 MHz 1 H-NMR of N,3-Diphenyl-2-pyrazoline-4,5- dicarboximide (83)...... 110

12 63 MHz 1 3C-NMR of N,3-Diphenyl-2-pyrazoline-4,5- dicarboximide (83)...... 111

1 3 250 MHz 1 H-NMR of 3-Pyrazoline-5-carbonitrile (87)...... 112

14 63 MHz 13C-NMR of 3-Pyrazoline-5-carbonitrile (87)...... 113

1 5 250 MHz 1 H-NMR of 3-Phenyl-1 -(trimethylstannyl)-1H-benz[f]indazole-4,9-dione (93)...... 114

VÜ 1 6 63 MHz 13C-NMR of 3-Phenyl-1-(trimethylstannyl)-1 H-benz[f]in-dazole-4,9-dione (93)...... 115

17 250 MHz 1 H-NMR of 3-Phenyl-1-trimethylstanny!pyrazole- 4,5-dicarboxylate (101)...... 116

18 63 MHz 13C-NMR of 3-Phenyl-1-trimethylstannylpyrazole- 4,5-dicarboxylate (101)...... 117

19 250 MHz 1 H-NMR of 3,4,5-Triphenylpyrazole (105)...... 118

20 63 MHz I^C-NMR of 3,4,5-Triphenylpyrazole (105)...... ,,.119

21 250 MHz 1 H-NMR of Bis(trimethylstannyl)benzalazine (118)...... 120

22 63 MHz 13C-NMR of Bis(trimethylstannyl)benzalazine (118)...... 121

23 250 MHz 1 H-NMR of a-Triethylsiiyl-a-trimethylstannyltoluene (129)...... 122

24 250 MHz 13C-NMR of a-Triethylsilyl-a-trimethylstannyltoluene (129)...... 123

25 300 MHz 1 H-NMR of a-Triisopropylsilyl-a-trimethylstannyltoluene (131)...... 124

26 75 MHz 13C-NMR of a-Tiiisopropylsilyl-a-trimethylstannyltoluene (131)...... 125

27 250 MHz 1 H-NMR of a-Dimethylphenylsilyl-a-trimethylstannyitoluene (133)...... 126

28 63 MHz ‘•3H-NMR of a-Dimethylphenylsilyl-a-trimethylstannyltoluene (133)...... 127

29 250 MHz 1 H-NMR of a-Cyclohexyldimethylsilyl-a-trimethyl- stannyltolusns (135)......

30 63 MHz ‘•Sc-NMR of a-Cyclohexyldimethylsilyl-a-trimethylstannyltoluene (135)...... 129

v iü 31 250 MHz 1 H-NMR of (E)-2-Ethoxy-1-phenyl-1-trimethyl- stannylcydopropane (139) ...... , 130

3 2 63 MHz ISC-NMR of (E)-2-Ethoxy-1-phenyl-1-trimethyl- stannyicyciopropane (139) ...... 131

33 300 MHz 1 H-NMR of (E)-2-Butoxy-1-phenyl-1-trimethylstannylcyclopropane (141) ...... 132

34 75 MHz ‘•3C-NMR of (E)-2-Butoxy-1-phenyl-1-trimethylstannylcyclopropane (141) ...... 133

3 5 300 MHz 1 H-NMR of (E)-2,4-dihydropyranyl-1 -phenyl-1 - trimethylstannylcyclopropane (143)...... 134

3 6 75 MHz 13C-NMR of (E)-2,4-dihydropyranyl-1-phenyl-1- trimethylstan nylcyclopropane (143)...... 135

3 7 300 MHz 1 H-NMR of 2,2-Dimethoxy-1-trimethylstannyl-1 -phenylcyclopropane (147) ...... 136

3 8 75 MHz 13C-NMR of 2,2-Dimethoxy-1-trimethylstannyl-1 -phenylcyclopropane (147) ...... 137

3 9 250 MHz 1 H-NMR of Phenyl(triphenylstannyl)diazomethane (161) ...... 138

4 0 250 MHz 1 H-NMR of Phenyl(triphenylplumbyl)diazomethane (162) ...... 139

41 250 MHz 1 H-NMR of p-Chlorobenzoylbenzalazine (173) ..... 140

4 2 83 MHz 13Q-NMR of p-Chlorobenzoylbenzalazine (173) ..... 141

43 250 MHz 1 H-NMR of p-Trifluoromethylbenzoyi- benzalazlne (174)...... 142

4 4 63 MHz 13C-NMR of jO-Trifluoromethylbenzoyl- benzalazine (174)...... 143

4 5 Metal Diazocarbon Ylide ...... 145

Ix 4 6 Metal Diazocarbon-olefin Complex ...... 146

4 7 Most Stable Intermediate Predicts Z-Cyclopropane for Phenyldiazomethane ...... 147

4 8 Hybrization to sp2 Carbanion Predicts Formation of the E-Cyclopropane for Ethyl Diazoacetate ...... 148

4 9 Hybrization to sp2 Carbanion Predicts E-Cyclopropane for Phenyl(trimethylstannyl)diazomethane ...... 149

5 0 Preferred Approach of Metal Diazocarbon to Form Most Stable Complex...... 150

51 Most Stable Intermediate Predicts Z-Cyclopropane forW(CO)5CHC6H5 ...... 151 LIST OF TABLES

TABLE PAGE

1 Mercury Derivatives of Diazomethyl Compounds ...... 3

2 Preparation of Dimetallated Diazomethanes by the Metal Amide Method" ...... 7

3 Preparation of Silyl and Germyl Diazo Compounds from Uthium Tosylhydrazones ...... 11

4 Cycloaddition Reactions of Organometallic Diazomethanes with Dimethyl Acetylenedicarboxylate ...... 13

5 Alkylation of Silver Diazocarbonyl Compounds With Organic Halides ...... 15

6 Synthesis of a-Silyl Esters and Ketones by Rhodium(ll) Acetate-Catalyzed Decompositions of Diazo Compounds in the Presence of Triethylsilane ...... 47

7 Synthesis of a-Silyl-a-trimethylstannyltoluene Derivatives by Rhodium(ll) Acetate-Catalyzed Decomposition of 70 in the Presence of Organosilanes ...... 49

8 Rhodium(ll) Acetate Catalyzed Reactions of Phenyldiazo methane (76) with Representative Olefins 58

9 Rhodium(ll) Acetate Catalyzed Reactions of Ethyl Diazo acetate (146) with Representative Olefins ...... 60

10 Relative Reactivities of Diazo Compounds for Si-H insertion and Addition to C-C Double Bonds ...... 63

x i STATEMENT OF PROBLEM

Interest in a-metalloido and a-metallo diazo compounds and their corresponding carbenes has increased greatly over the last few years. Diazo compounds containing group IV atoms, e. g. silicon and germanium, have been of particular synthetic and mechanistic interest. As yet there has not been any thorough investigation involving a diazo compound containing an a-trialkylstannyl group attached to the diazo function. Furthermore, methodology for lithiation or metallation of diazo compounds that contain a- hydrogen is very limited.

The present study involves investigation of the synthesis and chemistry of phenyl(trimethylstannyl)diazomethane, its subsequent carbene and/or carbenoid and lithium phenyldiazomethane. Of particular importance in this investigation is developing practical methods for the synthesis and utilization of phenyl(trimethylstannyl)diazomethane and lithium phenyldiazomethane.

Through this study knowledge of a métallo diazo compounds is to be extended. HISTORICAL

A. Introduction

Mercuric ethyl diazoacetate (1), the first a-metallated aliphatic diazo compound to be prepared, was reported in 1895 by Buchner etal (Eq, 1).1

11^ ?\ HgO ^ 11^ \ (^\ 2 H— C— C— OCHgCHa ------► Hg C— C—S OCHgCHg) g V) -HgO 1

There was little subsequent interest in métallo diazo compounds until preparation of lithium diazomethane ( 2 ) from diazomethane and methyllithium was described in 1954 (Eq. 2 ) 2 In recent years, besides development of the

CH,U ]j2 H — C — H . Q u H— C — Li (2)

chemistry of aliphatic diazo compounds, there has been increased of activity in the synthesis and reactions of diazo compounds containing metalloids and metals bonded directly to the diazo carbon.

The subsequent historical section will be divided into two parts. In part B synthesis of diazo compounds containing metalloids and metals adjacent to the diazo carbon will be described. In part C the chemistry of these types of diazo compounds will be summarized.

2 B. Synthesis of a-Metalloldo and a-Metailo Diazo Compounds

Mercuration of diazomethyl compounds as in Equation 1 is usually carried out with mercuric oxide in aprotic solvents. Examples of such mercurations are illustrated in Table 1. Mercury derivatives of diazo compounds are generally quite stable and, as will be described later, are synthetically useful reagents.3

Table 1. Mercury Derivatives of Diazomethyl Compounds

11^ f 2 R—C— H + HgO -► R-—C' Hg- HoO

R Yield % R Yield %

— C— CHg 83 ——0— G H =C H — CgHg 67

H — CFg 95 — C— CgHg 97

? — C = N 80 — C— CH2 C6 H5 55

N—SO2 CH3 — COO-t-C,^ Hg 64

if ---- C--- C(CHg ) 3 81 82 \ hs Silver diazo compounds 3 are preparable via direct metallation of

primary diazo compounds with silver oxide (Eq. 3),'^ Silver a-diazo ketones

Ag^O N 2 — — A g - C - R

(3)

H H ^ R = — COC2H5 , — CCH3 , — CC5H5 , — P(0C2Hs)2 and — P(CgHs)2

and a-diazo esters are considerably less stable than their mercury analogs.

Silver derivatives of a-PO-substituted diazo compounds however can be isolated without difficulty.

Disilver diazomethane (4) has been synthesized by reactions of

diazomethane with silver(l) salts at -5 oc in aprotic solvents (Eq. 4).5 Disilver

diazomethane (4) may be stored in the dark under argon for several months

without change, but is light sensitive and decomposes in daylight under air

within a few days yielding silver cyanide as the major product.

? 2 AgOCCHg + S H—C— H -2N0 Ag— C— Ag + 2 CH3OCCH3 (4

Lithium diazomethane (2) can be prepared at -78 °C from diazomethane

with methyllithium^ (Eq.5), phenyllithium^ (Eq. 6 ) and lithium N-methyl-N-

trimethylsilylamideS (Eq. 7), respectively. The related sodium derivative, 5

Na CH3U Na H—C—H . Q|_| H—C—Li (5) 2

Na C3H3U Na H— C — H . QgHg H—-c- C — Li (6) 2

N2 (CH3)3SiN(CH3)LI 5)2 H—c—H "ZTTTTTZTTT H—c~u (7) (CH3)3SiN(CH3)H 2

N a C ( N 2 )H, has been synthesized from diazomethane and triphenylmethyisodium.7 Both lithium diazomethane (2) and sodium diazomethane are handied in suspension, since they are highly explosive in the dry state. The lithium derivative of ethyl diazoacetate (5) can be prepared

at -100 °C using n-butyllithium in ether (Eq. 8 ) .8 Dimethyl-

phosphonodiazomethane, HC(N 2 )PO(CH 3 )2 , is metallated under similar

conditions.9

Na O n-BuU 5|a ^

H— C— C— OC2 H5 . Li—C—C—OC2 H5 (8 ) 5

Little is known about magnesium, zinc or cadium diazoalkanes. The

Grignard reagent, methyl magnesium iodide, is reported to react with ethyl

diazoacetate at -65 OC to form ethyl iodomagnesium diazoacetate ( 6 ); 6 is

stable only in solution (Eq. 9).10

Ma 0 CH^Mgl N:

H—C— C— OC2 H5 _ Qu IMg— C— C— OC 2 H5 (9) Neutralization of diazomethyl compounds with suitably substituted metal amides has been used to prepare zinc and cadmium bis (ethyl diazoacetates)

(7, Eq. 1 0 ) . The preparative methodology is known as the "Metal Amide

Method". Compounds 7 can be isolated as slowly decomposing oils.

Ng Cj> M{N[Si(CH 3)3]}2 jj)

2 H—C—C—OCgHs - 2 HN[Si(CH 3)3] m (— C—C—OCgHg): (1°)

M — Zn, Cd

Similarly, arsenic-, antimony- and bismuth- substituted diazomethanes 8 have

been obtained from primary diazo compounds and substituted metal amides (Eq.11).12

(CH3)3MN(CH3)2 N2 ------► jja n - HN(CH3)2 (CH3)2M*~^^“R ( 11) 8

M = Sb, Bi, As

R = H ,C 02CH3 ,C 0 C6H5

The "Metal Amide Method" has also been used to Introduce two

germanium-, tin- or lead- containing groups into diazomethane.13 Examples

of thermally stable dimetallated compounds prepared as above are given in

Table 2. TABLE 2. Preparation of Dimetailed Diazomethanes by the "Metai Amide Method"

11^ H—C—H +2R3MN(CHg)2 MRg—C—RgM + 2 HN(CH 3)2

R M Yield %

CH3 Ge 58 CH3 Sn 95 C2H5 Sn 82 /7-G4H9 Sn 46 CeHs Sn 90 CH3 Pb 100

Ethyl diazoacetate undergoes stannyiation using trialkylstannyldimethyi- amine compounds to yield diazoethoxycarbonylmethyltin derivatives 9. In a simiiar reaction, dialkyltin bis dialkylamides react with ethyl diazoacetate to produce bis[diazoethoxycarbonylmethyl]tin derivatives (10, Eq. 1 2 ).’'4

RgSn— N(CH 3)2 RgSn— C—C— OC 2H5 -(CH3)2NH 9

H—C—-C— OC 2H5 R = CH3 , C2H5 , n - C^Hg (12)

RgSn— [N(CH 3)2]2 (0.5 equiv) N

(CHa)2NH 10 8

Another important method for preparing métallo diazo compounds is metallation of metallodiazoalkanes (transmetallation). In this process, the metal atom of a metallated diazo compound is exchanged with another metal. Such transmetallations are generally performed by treating a metallated diazo compound with the appropriate organometallo halide to form the new metallated diazo compound. For example, lithium ethyl diazoacetate reacts at low temperature (-100 °C) with trialkylmetal halides to form the corresponding metallated diazoesters (11, Eq. 13).15

Li—C— OCgHg - LiCI (CHg)a M—C—C—OC 2H5 (13) 5 11

M = Si (52 % ), Sn (50 % ), Pb (10 %)

A variant of this method consists of using an organometallic sulfide in place of an organometallo halide to prepare a-metallated diazo compounds

(12, Eq. 14). 16

Ng O [(CH 3)3Ml2S Ng O Hg ( — C— C— 003145)2 ^ ^ (CH3)3M -—0 — 0 — OC2H5 (14) 1 ^ 1 2

M = Si (75 % ), Ge (57 % ), Sn (30 %)

By extension of the above methods, lithium diazomethane (2) can be

made to undergo dimetallation. For example, various trialkylmetal halides and 2 at -78 °C yield bis(trialkylmetal)diazomethanes 13. in these sequences, lithium diazomethane ( 2 ) lithiates the intermediate metal diazomethane; the lithium trialkylmetaldiazomethane generated then reacts with the trialkylmetal halide to give 13 (Eq. 15).17

^ 11^ 11^ 2 Li— C— H + 2 R3 MCI _ 2 LiCI R3 M—0 —MR3 + H—0 —H

M = G e, R = C6Hs(44%)

M=Sn, R = C6 Hs (56%)

M = S n , R = CH3 (80 %)

Lithium diazomethane (2) and trimethylsilyl chloride however yield trimethylsilyldiazomethane (14) rather than bis(trimethylsilyl)diazomethane (15).

Synthesis of 15 can be efficiently accomplished from 14 and n-butyllithium and then trimethylsilyl chloride (Eq. IS)."*®

N2 1) n-BuLi N2

^ ^ " 2) (CH3 )3 SIGI (CH3 )3 Si— C - H 14 (16)

1) n-BuU Ng

2) (CH,),SICI ' (CHakSi-LsKCH,), 15 10

Of further interest Is that lithium diazomethane Is converted by cadmium chloride at -78 °C to cadmium bls(dlazomethane) (16, Eq 17)J9

2 Li—C—H + CdClg ► H—C—Cd—C—H ( 17) 2 -2 UC\

Routes to a-metalloldodlazomethanes have also been developed which

Involve Introduction of the metal before creating the diazo function. An example of this synthetic method Is generation of trimethylsllyldlazomethane (14) from

N-nltroso-N-trimethylsllylmethylurea and potassium hydroxide (Eq. 1S).20

20 % KOH i|2 (CH3)3SiCH2N(NO)CONH2 ------► (CH3)3Si— 0 —H (18) 14 64%

Metalloldo diazo compounds may also be obtained by diazo transfer reactions of organometallic reagents. Thus 14 can be synthesized efficiently from trimethylsllylmethylmagneslum chloride and diphenyl phosphorazldate

(Eq. 19).21

Mg (CgH 50)2P(0 )N3 (CH3)3SiCH2C I ► [(CH3)3SICH2MgCI] ------►

(19 ) I|2 — ------► (0143)381 —C—H (C6H50)2P(0)NH2 14 85% 11

{Pentamethyldisilanyl)diazomethane, (CH 3 )3 SiSi{CH3 )2 C(N 2 )H, has been prepared similarly by the diazo transfer method .22

Very stable metalloido diazoalkanes such as a-silyl and a-germyl- diazoalkanes have been obtained via the 'Bamford Stevens Reaction".23 This method involves heating lithium salts of tosylhydrazones of acylmetalloids in aprotic environments, examples of which are summarized in Table 3.

Table 3. Preparation of Silyl and Germyl Diazo Compounds from Lithium Tosylhydrazones

Ü N—I s N -UTs 11^ R1,M_L, R2 R \,M - C —r 2

R'aM Ff Yield %

(Ph3)sSi Ph 73

(^^3)3^1 Ph-p-F 63

(PhgjgSi CH3 82

(Ph 3)3Si CHgPh 65 (PhglgGe Ph 65

(CH3)3Si Ph 73

(CHgjgGe Ph 70 12

Metalloido diazoalkanes have also been prepared by oxidation of hydrazones of acylmetalloids. Thus phenyl(trimethylsilyl)diazomethane (17) has been obtained by reaction of phenyl (trimethylsilyl) ketone hydrazone with manganese dioxide (Eq. 20).24

N Ng II 2 MnOg II (CH3)3Si— C-CeHg ------:------^ (CH3)3Si—C-CeHg ( 20) HgO, -MngOa 1 7

Reactions of bis(triethylsilyl)- or bis(triethylgermyl)- mercury (18) with mercurial diazo compounds 19 in THF result in formation of unsymmetrical mercurials 20 which are thermally unstable. Subsequent elimination of

mercury yields the corresponding a-(triethylsilyl)- or a-(triethylgermyl)- diazocarbonyl compounds (21,.Eq. 21).25

ii= ? (EtaMj^Hg + H g (— C - C - r ), 18 19 (21)

Et3MHg”~C—C—R 513.^ m —C—C— X S - f R - Hg 20 ~ 21

M = Si, Ge

R = CH3 , CgHg, OCH 2CH3 13

C. Chemistry of a-Metalloldo and a-Metallo Diazo Compounds

Along with development of synthetic methodology for a-metaiioido and a-metaiio diazo compounds has been an interest in their chemistry. Limited

investigations have been made of their cycioaddition and substitution reactions, their thermoiyses and their photolyses.

Study of 1,3-dipolar cycloaddition reactions of organometallic

diazoalkanes with dimethyl acetylenedicarboxylate has been reported.

The initially formed A"!- pyrazoles rearrange by migration of the metal

group to give the a 2 - pyrazoles (Table 4). When mercury bis(diazoalkanes)

Table 4. Cycloaddition Reactions of Organometallic Diazomethanes with Dimethyl Acetylenedicarboxylate

__ R^aM—C“ R^ + CHgOgCGssrsCCOgCHa ►

CH3C02

CHoCO^

R^M Ff Yield %

(CHg) 3Sn (^ 143)380 94

(CH3)3Sn CO2CH2CH3 84

(CH3)3Pb (CH3)3Pb 100

(CH3)3Pb CO2CH2CH3 87

(CH3)2Sb CO2CH2CH3 43

(CH3)gBi CO2CH2CH3 93 14

{Hg[C(N2)R]2. R = CO2CH2CH3, COCH3} react with dimethyl acetylene dicarboxylate the products obtained are the mercury bis - a 1 - pyrazoles 2 2

(>80%) (Eq. 22).26

li’- Hg (— C—R2)g + CH 3O2CCSCCO 2CH3 ------^

(22)

COgCH;

Mercuric ethyl diazoacetate (1) undergoes substitution reactions. Thus 1 may be halogenated to 23, C-alkylated to 24, silylated to 25 and stannyiated to

26. Notewohny are the metallating reactions with [(trimethyl)silyl] sulfide and bis[(trimethyl) or (triphenyl)sîannyl] sulfide (Eq. 23).27

II 11^ ? Hal— C— C—OC 2 H5 (CgHg)gC— C— C— OC 2 H5 23 Hal = I , Br,Cl V '2 . Brg X o r SOCI2 (C6Hg) 3CBr

^ n Hg (— C-C-0C2 Hs )2 (23) 1

[(GHg) 3 Si]2 S y / ^ 11)2 8 ; R = C H 3 , CgHg

. 11^ ? ^ ? (CH3)3Si—C—C—0C2Hg RgSn—C—C—0C2Hg 25 26 15

S trau sz et al report that when mercuric ethyl diazoacetate (1 ) is photolyzed at wavelengths shorter than 290 nm. ethoxycarbonylcarbyne (27) is generated.(Eq. 24). Photolysis of 1 in tetrahydrofuran gives the solvent-derived product 28 (Eq. 2 5 ).28

1)2 hv . ? H g (— C—C—OCgHs): ------► 2 :c—c —oCoHs (24) Hg, -2Ng 27

CH 2 CO 2 C 2 H 5 (2 5 ) -H g. -2Ng 28

Silver derivatives of diazo ketones and diazo esters, though not isolated, have been used directly in substitution reactions.29 Examples of these displacements are summanzed in Table 5.

Table 5. Alkylation of Silver Diazocarbonyl Compounds with Organic Halides

11' Ag- ■Ri R 2—X Ri- ■R2 + AgX

R2—X Yield %

Cj) — C—OC2H5 H2C=CH —CHgH 66 CgH g—CHg— Br 59 g — 0—GH3 H2C=CH—CH2~I 25 0 — c — CgHs H2C = C H -C H ^ I 55 16

Further, lithium ethyl diazoacetate 5 undergoes satisfactory substitution reactions (Eq. 26).30 Thus 5 can be methylated to 29, benzoylated to 30, silylated to 31 and stannyiated to 32.

» II II CH3—C—C—OC2H5 CgHg—C—C—C—OC 2H5 2 9 3 0

4 3 % 4 5 % CH,I

Li— C—C—OC2H5 (26) 5 (CH3)3SiCyX \(C4H9)3SnCI y / 4 7 % 45 % X .

. 11^ ? 11^ ? (CH3)aSi— C—C—ÜÜ2H5 (C4Hg) 3Sn—C—C—OC2H5 31 3 2

Lithium trimethylsilyldiazomethane (33) reacts with alkyl halides to yield a-trimethylsilyldiazoalkanes 34 which can be oxidized with m-chloroperbenzoic acid (m-CPBA) to acylsilanes 35 in good yields.3"l

RX + Li— C—Si(CH3)3 ------► 3 3 (27) Ng O II m-CPBA II R -C — Si(CH3)3 ------► R—C— Si(CH3)3 3 4 - ^ 2 3 5

RX = CgHgCHgCI (77 %), CH3(CH2)gBr (65 %),

CH2=CH(CH2)9 l(7 2 %) and C 6H50(CH2)3Br (62 %) 17

Copper-catalyzed thermoiyses of a-(triethylgermyi)diazo ketones 36 in hexane at 80-90 °C produce germyiated keto-carbenes 37 which rearrange to monogermyiated ketenes 38 (Eq. 28). Ketenes 38 do not dim erize.32

?\ Cu :CH3CH2)3Ge—C—C—R (CH3CH2)3G0—C—C—R 36 N, 37 (28) (CH3CH2)3Ge, _CL ; c = c = o

38 R = CH3,CH3CH2,CgH5

Thermolysis of trimethylsiiyidiazomethane (14) at 440 °C and 10 mm.

Hg pressure yields vinyidimethylsilane (39), els-and trans-1,1,2,3,3,4- hexamethyi-1,3-disiiacyciobutenes (40), 3,3,4,4-tetramethyi-3,4-tetramethyi-

3,4-disila-1-hexene (41), vinyitrimethyisiiane (42) and invoiatiie products

(Eq. 29).33 The dimerization products 40 are thought to be derived

(CH3)3Si— C—H (CH3)2HSi— CH =CH 2 + 14 -N, 39

+ (29)

H,C‘ 40 40

CH3CH2(CH3)2Si— Sl(Cl^)2—CH =:CH2 + (CH3)3Si— C H = C H 2 41 42 18 from 2-methyl-2-sila-2-butene (44), Silaolefin 44 is formed via 43 by migration of a methyl group from the silyl group to the carbene carbon (Eq. 30).

This investigation demonstrates that migration of an alkyl group to a

CH3 , CH3 (CH3)3Si— C— H (CH3)3SI— C— H c h / = ' ^ h 14 -N, 4 3 44 carbene carbon occurs with a-silyl diazo carbenes as it does with aliphatic diazo carbenes.

Photolyses of trimethylsilyldiazomethane (14) at 25 °C in 2-propanol,

3-ethyl-3-pentanol, 2-methyl-2-propanol and diethylamine give ethyldimethyl-2- propoxysilane (45), ethyl(3-ethyl-3-pentoxy)dimethylsilane (46), ethyldimethyl-2-propoxysilane (47) and ethyldlmethyl-N,N-diethylaminosilane (48), respectively (Eq 31).33

N, II /)/ ■ ■ (CH3)Si— O—H _------► (0143)381 — O —H (31) 14 N, 43

[(CH3)2Si=CHCW )] Hg)2NH ^ (CgH5)2(j)—CH 2CH3 44 N(CH2CH3)2 48

(CH 3 )2 Sj— C H 2 CH 3 (0143)28 ^ CH2CH3 (0143)2 Sh OH 2CH3 )0 (0 H3)3 0-C(OH2CH3)3 °^CH(CI^ )2 4 6 45 19

Photolysis and pyrolysis of (pentadisilanyl)diazomethane (49) generate a-silyicarbene 50; exclusive migration of the trimethylsilyl group gives silene

51. Trapping of 51 with tert -butyl alcohol, acetone and benzophenone gives te n -butoxysilane 52, silyl end ether 53 and vinylsilane 54 via Wittig-type reactions , respectively. Pyrolysis of 49 at 450 ©C results in 1,3-disila- cyclobutane 55 as a mixture of cIs- and trans-isomers; ratio 41:59 (Eq. 32).22

Ng II hv ox ùk. ■ ■ (CH3)3SiSi(CH3)2— C— H ------► (CH3)3SiSi(CH3)2— C— H (32) 49 -Ng SO

Si(CI^ )3

^ [(CH3)2Si=CHSI(Cl^)3]------► (CH3)2Si(^i(CI^)2

Si(Cli)3 (CH,)3C0 H , V

A (47 %

(CH3)2Si—CH2SI(CH3)3 (CH3)2SpCH2SI(CH3)3 (CgH5)2C=CHSi(Ckt)3 0C(CH3)3 52 1 A (58%) hv (41 %) 5 3 ® +

/,v(2 8 %) (CH3)2Si=0 A (54) %

Triisopropylsilyldlazomethane (56) can be lithiated using n-butyllithium.

Subsequent reaction with triisopropylsilyl chloride gives a C- and N-silylated nitrile imine (57, Eq. 33).34 Also, 57 is stable enough to be distilled at 90-100

°C (0.15 torr) without decomposition (80%). Of particular importance is that silylation occurs on terminal nitrogen instead of on carbon of the diazo anion. 20

The non-equivalence of the silicon atoms in the 29g; n m r spectrum, excluded formation of the diazo isomer {[(CH 3 )2 CH]3 SiC(N2 )Si[CH(CH3 )2 ]3 ) (Eq. 33).

1) BuU 11^ [(CH algCHjaSi— C— H 56 2) [(CH3)CH]3SiCI (33) © O [(CH3)2CH]3SF IN—N— Si[CH(Cti)3b 57

The behavior of bis(trimethylstannyl)diazomethane (58) demonstrates the sensitivity of a trimethylstannyl group to acids and bases. Furthermore, the absence of reactions with styrene and diphenylacetylene suggests that highly activated dipolarophiles are needed for 58 to undergo cycloaddition (Eq. 34).35

(CHg)3Sn—C — Sn(Chb)3 (34) 58

no reaction

O H ©

no reaction

no reaction 21

Ando et al have investigated the thermolytic behavior of phenyl-

(trimethyisiiyl)diazomethane (59). Pyrolysis of 59 yields two identifiable products: 1,1-dimethyl-2,3-benzo-1-silacyclopent-2-ene (60) and the coupling product 61 (Eq. 35).36

0 % ^ ^ - C — Si(Cti)3 60 (35)

69 (CH3)3Sk C^Hs

CgHg' Si(Cli)3 61

A mechanistic study by Barton, in which the diazo carbon of 59 is

labelled with 1^0 reveals that benzosilacyclopentene 60 is formed via a

phenylcarbene-cycloheptatrienylldene interconversion (Eq 3 6 ).37

i(Chb)3 ------► I S>r-Si(CHb)3

I^K^i(CH3)3

V > s „ c ^ ) 3 — " Q r

H—C

^ 60 | h > 22

The Barton study disproves the alleged intermediacy of siiacyclopropane

62 in pyrolysis of phenyl(trimethylsilyl)diazomethane (59) to form 60, since the labelled carbon would have remained aliphatic in the Ando mechanism (Eq. 37).36

i(Cli)3 C—H Insertion

62 CH, (37)

“CH CH. 6 0 C H

Pyrolysis of phenyl(trimethylsilyl)diazomethane (59) in the presence of carbonyl compounds gives styrene derivatives S3, bsnzosilacyclopentene 60

and coupling product 61 (Eq. 38).38

500 °C — SI(CI^ )3 + R’— c — R2

5 9 (38)

WR1d 2

CgH/ S i(C % 6 3 6 0

= r 2 = CHg (23%) R ’ = r 2 = (CHglb (11 %)

r 1 = H , r 2 = Cglt (28%) 23

Jo n es et al reported a study of pyrolysis of phenyl(trimethyigermy!)- diazomethane (64). Thermolysis of 64 at 450 OC yields three products;

1,1-dimethyl-2,3-benzo-1-germacyclopent-2-ene (65), styrene (66) and a-methylstyrene (67, Eq. 39).

N, Ge(CH3)3 .. - Ng

(39)

66 67

Benzogermacyclopentene 65 is believed to be derived from carbene-to-

carbene rearrangement. However, styrene (66) is rationalized as being formed

from the germacyclopropane 68 by expulsion of dimethylgermylbene

(69, Eq. 40).39

Ge(CH3)3 OA CH, 68 (40)

» + H3C—Ge—GH3 69 RESULTS AND DISCUSSION

The present study involves investigation of the chemistry of phenyl(trimethylstannyl)diazomethane (70), its subsequent carbene 71 and/or carbenoid and lithium phenyldiazomethane (72). Both 70 and 72 have not

.. 11^ CgHg— C— Sn(CHg ) 3 CgHg—C—Sn(CHg ) 3 C g H g — C — Li 7 0 71 72

been previously reported; thus, their synthesis and chemistry may add significantly to the disciplines of diazo chemistry.

Synthesis of Phenyl(trimethylstannyi)diazomethane (70)

Initial attempts to prepare 70 involved deprotonation of phenyldiazomethane (76) by strong bases and subsequent reaction with trimethyltin chloride (78) (Eq 41). In the present work 76 was obtained by

N 2 1 .R U CgHg—C— H — ------► 7 0 (41) 76 2. (C%SnCI

R = CHg, n - Bu, sec -Bu, tert- Bu

2 4 25

vacuum decomposition of the sodium salt of benzaldehyde p- to lu e n e - sulfonylhydrazone as prepared from benzaldehyde, p- toluenesulfonyl hydrazide (73) and sodium methoxide by the sequence in Equation 42.

ySO gC gH^ CH 3

K SO2C6H4CH3 N—N. + CgHg—C— H -H g O CgHg— C—H H H 74 73 (42) .SOgCgHtCHg

NaOCI^ N, Na - CH3OH CgHg— C—H - NaS%h*Cky CgHg—C—H 75 76

Commercial trimethyltin chloride (78) is expensive and was presently prepared

on a large scale from méthylmagnésium iodide and tin(IV) chloride as in

Equations 43a and b.

4 Ct^Mgl + SnCl, - (CHgjijSn (43a) ■4MglCI 77

3 (C l^ S n + SnCIt -► 4 (C%SnCI (43b) 77 78 26

Numerous attempts to prepare 70 by reacting 76 with aikyllithiums: methyilithium, n -butyllithium, sec -butyilithium and tert -butyllithium, with subsequent addition of 78 were unsuccessful. Inverse addition of reactants 76 and alkyllithium reagents also failed. Furthermore, using tetramethylethylenediamine (TMEDA) with an alkyllithium in ethyl ether or tetrahydrofuran did not help (Eq 44). These experiments will be discussed in greater detail later.

1.RU

CgHs— C— H ------► 7 0 (4 4 )

2 . (C % S n C I

R = CHg, n - Bu, sec - Bu, fert-Bu

Synthesis of 70 is achieved via the " Metal Amide Method" from phenyldiazomethane (76) and diethylaminotrimethylstannane (79).

Aminostanne 79 is prepared by deprotonation of diethylamine with n - butyllithium at - 78 OC, followed by addition of trimethyltin chloride (78)

(Eq 45). Then, 70 is synthesized in 80 % yield by refluxing 76 with 79 in

(C % S n C I n ~ BuLi 7 8 (CH3CH2)2N—H ------► (CH3CH2)2N— Ü ------► (45) - n -BuH . LiCl

(CH3CH2)2N-Sn(CH3)3 79 27

petroleum ether (bp 60-90 °C) for approximately twenty hours. Distillation gives

70 in high purity (Eq 46). Of note is that the reaction to give 70 proceeds very

îl= CgHs—O—H + (CH3CH2)2N—Sn(CH3)3 .(C^tC%NH CeH5^C-Sn(CH3)3 (46) 7 6 7 9

slowly in refluxing pentane. The success of the synthesis of 70 in refluxing petroleum ether (bp 60-90 °C) appears to depend upon the reaction temperature, the thermal stability of 70 and that the reaction is driven to completion by removal of the diethylamine.

A mechanistic rationale for the formation of 70 involves initial 1,3- addition of 79 with 76, followed by elimination of diethylamine (Eq 47).

Q:N, .Sn(CH3)3 7 6 + 7 9 7 0 (4 7 ) - HN(CliCH3)^ (c h 3CH2)2 n : u

Phenyl(trimethylstannyl)diazomethane (70) is extremely moisture sensitive and must be kept under an inert atmosphere at all times. Under argon

70 can be stored in a refrigerator (10 °C) for months without any apparent decomposition. In contrast to phenyldiazomethane (76), which explodes violently when heated above 40 oc (0.45 mm), distillation of 70 at 28

100 OC (0.45mm) may be effected efficiently with no apparent danger. The impressive stability of 7 0 may be due to (p-d)n; back-bonding betw een the p-orbital of the diazo carbon and the empty d-orbitals of tin (Fig 1).

Sn (C %

Figure 1. Carbon - tin (p-d);c Back-bonding in 7 0

Cycloaddition Reactions of Phenyi(trimethyIstannyi)diazomethane

( 7 0 )

Cycloaddition of diazo compounds to electron-deficient alkenes and alkynes is a fairly well-established method for synthesis of pyrazolines and pyrazoles.40 Phenyl(trimethylstannyl)diazomethane ( 7 0 ) has now been shown to react readily with alkenes and alkynes to produce the corresponding pyrazolines and pyrazoles. The present studies of such reactions are described as follows.

When N-phenylmaleimide ( 8 0 ) is added to 7 0 at -15 °C and the mixture is warmed to room temperature (12h), reaction occurs to produce N,3-diphenyl-2-pyrazoline-4,5-dicarboximide ( 8 3 , 86 %, Eq 48). 29

70 + f N-CgH.

(CHa)3Sn CgHg O 80 81 (48)

+ [H] N— CgHg [Sn(CkWj

CgHg 82 8 3

Pyrazoline 83 is assigned on the basis of its IR, 1H-NMR, ISC-NMR, mass spectral and elemental analyses. Of particular interest is the IR spectrum of 83 which shows absorption at 3220 cm'1 for a N-H group. Supporting evidence from the 1H-NMR spectrum of 83 is a signal at 8.38 ppm which integrates for

one proton in the region expected for N-H in a pyrazoline. Furthermore, the

I^C-NMR of 83 reveals two distinct carbonyl signals (174.49 and 172.78 ppm)

and both the mass spectrum and elemental analyses are consistent with the

proposed structure.

There is no evidence that a trimethylstannyl group is present in the

isolated product. The trimethylstannyl group is totaliy replaced by hydrogen in

the final product 83. Since, Sn-N bonds are known to be very labile and

extremely air sensitive, great precaution was taken to eliminate moisture, i.e. dry

solvents and reaction under argon. In no instance could a product containing

the trimethylstannyi group be isolated. 30

Production of 83 is presumed to proceed according to Equation 48.

Intermediate 81 apparently undergoes metallotropic migration of its trimethylstannyl group to give a 2 - pyrazoline 82 with subsequent loss of the métallo group during reaction or work-up to give 83. Noteworthy is the fact that

TLC of the reaction mixture before work-up shows a major spot that has the same Rf - value as does the product 83 after Isolation.

1,3 - Dipolar cycloaddition also occurs with acrylonitrile (84) and 70 at -15 °C to room temperature to give 3-phenyl-2-pyrazoline-5-carbonitrile (87,

64 %, Eq 49). Ù? - Pyrazoline 87 (containing N-H) is the only product isolated.

,CN H. .H 7 0 + ^ C = C \ n 8 4 8 5 (4 9 )

+ [H]

IS n (C I^

The IR spectrum of 87 shows absorptions for N-H (3300 cm'1) and CM (2250 cm'l) groups. The H-NMR gives a N-H signal at 7.94 ppm. The structure of

87 is assigned on the basis that diazo compounds have been shown to add regiospecifically to mono-acceptor-substituied alkenes such as acrylonitrile

(84) and by comparison with the H-NMR of the cycloadduct of trimethylsilyl- 31 diazomethane (14) and acrylonitrile (84). Thus, the nudeophilic diazo carbon

of 70 forms a bond with the electrophilic p-position of 84 (Fig. 2).41 When 14

H _

©NI ------Ç

/B k ' ^ c CeH5^®\n(CH3)3 H ^ ® \ 70 84

Figure 2. Nudeophilic Diazo Carbon Attacks p- Position of Mono - acceptor - substituted Alkene

reacts with acrylonitrile the a 2 - pyrazoline 88 is obtained (Eq 50). The 1H-

[|2 \ (0143)38!— 0—H + yp—(I ^ N I (50) H ON Si(CH3)3^‘’ 88

N M R of 88 is reported to show a signal at 4 . 8 0 ppm for the hydrogen (Ha) on

carbon bonded directly to the cyano g r o u p . 4 2 The methine hydrogen on 87

gives a signal at 4 . 6 3 ppm, which is similar to that observed for the same type of

hydrogen (Ha) in 88. Also, the 1H NMR spectrum of 88 contains signais at 2.0

ppm for the methylene protons (Hp), which are upfield from proton Ha- These

effects, as expected, are observed for 87 in which methylene proton

resonances are observed at 3 .4 3 and 3 . 4 0 ppm. The structural assignment as

87 is also consistent with mass spectral and elemental analyses. 32

Reaction of 70 and 1,4 - naphthoquinone, surprisingly, gives 3-phenyl-

1-(trimethylstannyl)-1H-benz[f]indazole-4,9-dione (93,92 %, Eq 51). The structure of 93 is assigned on the basis of its IR, ‘•h n m R, IS n m r .

7 0 +

(CH3)3Sn CgHg Q 90

(CH3)3Sn |_| jj

(5 1 )

(CH3)3Sn (CH3)gSri

8 9

mass spectral and elemental analyses. The IR of 93 indicates the presence of different carbonyls by absorptions at 1670 and 1650 cm'1. Furthermore, the

13C NMR(Dept) of 93 shows two distinct carbonyls at 180.09(s) and

178.56(s).ppm. Of particular importance is that the product has no NMR for methine protons as would be the case for 91. Presence of the methyl groups of

93 demonstrated by the iH NMR signals at 0.79 ppm (integrating for 9 H s). 33

Formation of 9 3 is presumed to occur as in Equation 50. When 7 0 cycloadds to 8 9 pyrazoline 9 0 is formed which undergoes metallotropic rearrangement to give 9 1 , Bis-enolization of 9 1 to 9 2 which is then oxidized by 8 9 yields 9 3 . Interestingly, the trimethylstannyl group stays on nitrogen in 9 3 . Since, pyrazole 9 3 is highly conjugated, perhaps back-bonding between its nitrogen and tin atoms strengthens their connectivity so that the trimethylstannyl group is retained.

A similar explanation of reaction of ethyl diazoacetate ( 9 4 ) and 1,4-naph thoquinone ( 8 9 ) to produce pyrazole 9 8 rather than pyrazoline 9 6 h as been proposed by F i e s e r .4 3 Oxidation of intermediate 9 7 is stated to give 9 8 (Eq 52)

n + (52) 94 0 89

CH3 CH2 O2 C H Q CH3CH2O2C o 95 96

CH3CH2O1 CH3CH2O2C 34

Dimethyl acetylenedicarboxi'iste (99) is found to react with 70 to give dimethyi 3-phenyl-1-trimethylstannylpyrazole-4,5-dicarboxylat0 (101, 87 %, Eq

'O2CH;

7 0 + C H 3 O 2 CC 5 CCO 2 CH 3

9 9 ‘CO2CH;

100 (CH3)gSn (5 3 ) yC02CH3

CO2CH3

53). Formation of 101 is presumed to occur via migration of the trimethylstannyl group in 100 to yield 101, a A^-pyrazole. The presence of the trimethylstannyl group in 101 is confirmed by its 1 H-NMR and I^C-NMR spectra. Furthermore, the mass spectral and elemental analyses are consistent with the proposed structure.

The thermal stability of 70 as discussed earlier suggests that 70 could be suitable for cycloaddition reactions at high temperatures. Hence, it seemed likely that 70 could be forced to add to reactants that are usually considered to be poor dipolarophiles. Indeed, when 70 and diphenylacetylene (102) in petroleum ether (bp 60-90 OC) are heated in a glass bomb at 150 °C

(10 atm) for four days, 3,4,5-triphenylpyrazole (105, 56 %, Eq 54) is obtained 35

7 0 + CgH gC— CCgH g 102

103 (54)

1 0 5

Pyrazole 105 shows IR (3200 cm’"*) and 1H NMR (12.5 ppm) evidence for a

N-H group. The "*3c NMR, mass spectral and elemental analyses are consistent for the structure assigned as 105. Presumably, after metallotropic rearrangement of 103 to 104, the trimethylstannyl group is replaced by hydrogen at elevated temperatures.

Success in the reaction of 70 and diphenylacetylene (102) stimulated interest into the possibility of using electron-rich alkynes for cycloadditions with

70 at high temperatures and pressures. 3-Hexyne (106) and 70 were thus

reacted in a bomb at 150 °C (10 atm) for several days, but the corresponding

pyrazole 107 was not observed (Eq 55). Similarly, when bis(trimethylsilyl)

H ,GH2GH3 A

7 0 + C H 3 GH 2 GECCH 2 CH 3 (55) 1 0 6 HoGHo 36

acetylene (108) and bis(trimethylstannyl)acetyiene (110) are heated with 70, the corresponding pyrazoles 109 (Eq 56) and 111 (Eq 57), respectively, are not obtained. Apparently, these alkynes are not activated enough to react with

7 0 .

i(CH3)3 A 70 + (CH3)3SiC=CSi(CH3)3 (56) 1 0 8 K Si(CH3)3 6^5 1 0 9 H jij^^ySn(CH3)3

70 + (CH3)3SnC=CSn(CH3)3 (57) 110 / Sn(CH3)3 CsHs 111

Bromination of Phenyl(trimethyistannyl)diazomethane (70)

Conversion of diazo compounds to geminal dihalides has been

previously reported. For example, diphenyldiazomethane reacts smoothly with

sulfuryl chloride to give diphenyldichloromethane (112, Eq 58).44

Cl -Na CcH r— 0 —CcHi6^5 SOfeClg CgHg— 6 —C6^5rH (58) -SO, 01 112 37

Of special interest is whether there will be halogenative displacement of the trimethylstannyl group of 70 with bromine.

The reaction of phenyl(trimethylstannyl)diazomethane (70) with two

equivalents of bromine has been presently investigated. Bromine in

dichloromethane is found to convert 70 at 0 °C to a,a,a - tribromotoluene

(113, 82 %, Eq 59).

Br 70 + 2Big ------► CgHg—C—Br + (CH^SnBr (59) Br 113

Tribromide 113 is a white crystalline solid of proper melting point.45

The 1H-NMR of 113 shows only aromatic protons (8.06-7.42 ppm) as expected.

T he‘•^C-NMR of 113 consists of five signals indicative of four aromatic

carbons and one benzyl carbon.

It is presumed that the overall sequence for preparation of 113 involves

displacement of nitrogen from the diazo moiety to give 114 and then

substitution of the trimethylstannyl group (Eq 60). Formation of 113 suggests

D' ^ Brg _ f ______CeHs— C—Sn(CH3)3 ------CgHg— C—Sn(CH3)g 70 & 114 (60) Br Br, CgHg—Ç—Br (ChybSnBr & 113 38 that reaction of 70 with similar types of reagents could be of general synthetic value for preparing varied toluene derivatives.

Photolysis and Thermolysis of Phenyl(trlmethylstannyl)dlazomethane (70)

A major purpose of this investigation is study of the chemistry of phenyltrimethyistanny! carbene (71) as generated by photolysis and thermolysis of 70 (Eq 61). Thermal decomposition of trimethylsilyldiazomethane (14, Eq 29) has been found to give 2-methyl-2-silabutene,

hv /A CgHg— C—Sn(CHg)3 [CgHg— C - S n ( C H 3)3] (6 1 ) 7 0 71

1,1-dimethylsilacyclopropane and subsequent products.46 it was of interest to determine if carbene 71 behaves similarly (Eq 6 2 ) . Thus, 115 might be formed

/methyl \ ^migration j CH ,CH •C = S ri CH

(62)

( C-H insertion ) ■Sh

116 39

by methyl migration to the carbene carbon. It is unlikely that 115 is stable, but isolation of the dimer 117 would be evidence for formation of 115.

Stannaoyolopropane 116 will be produced if carbene 71 inserts into a C-H bond of a methyl group bonded to tin.

Photolysis of 70 with a medium pressure mercury lamp (X>300 nm) in benzene is found to yield bis(trimethylstannyl)benzal azine (118, 60%, Eq 63).

CeHjHsv yCHg H3C, / / / » [115] Srf HgC^ X CHs

1 1 7 (63) h v 70 116 -Ng

(CH3)gSn fgHg ^V = N M — N m =( _ _ q “ CsH/ ^^n(CHa)3 1 1 8

There is no evidence for formation of 115, its dimer 117, stannaoyolopropane

116 or any other tin derivatives. Azine 118 is single geometric isomer. Its 1H

NMR shows single signals for the methyl protons (0.33 ppm) of its

trimethylstannyl groups and the aromatic protons (7.64-7.36 ppm) of its

phenyl groups. Azine 118 exhibits six distinctive ‘l3C-NMR(Dept) signals 40

at 192.88(s), 140.79(s), 129.29(d), 128.29(d), 128.02(s) and -4.95 (q) ppm. The absence of any other signals suggests that azine 118 is a single geometric isomer. In theory three possible geometric isomers could be formed from 70:

118A-118C (Fig. 3). It is not known which geometric isomer of 118 is

Sn(CH3)3 Sn (0143)3 CgHg ^C — CgHg N-N N-N CgHg— (CHg)3Sn— Sn(CH3)3 6^5 118A 118B

CgHg ^C — Sn(CH3)3 yN—N (0143)380 — 0 ^

CgHg

1 1 8 0

Figure 3. Possible Geometric Isomers of Azine 11 8

presently formed.

Formation of 118 can be rationalized by at least three different

mechanisms. If carbene 71 is generated by photolysis of 70, then trapping of

71 by its precursor 70 can give 118 (Eq 64). It is also possible that 70 is 41

ÇeHs O 0 /n(CH3)3 70 O c 0 + N =N =C ,\ 11 8 (64) CcH6^5 $n(CH3)3 70 71

promoted to an excited state [70]* by light absorption. [3+3] Cycloaddition of

[70]* might yield 119 from which elimination of nitrogen from 119 gives 118

(Eq 65). A third possibility is attack of [70]* on 70 to form open-chain

70 ^|^Sn(CH3)3 70 [70] 118 (65) (CH3)3Sn-yt^.^^ -Ng CfiH6^5 1 19

intermediate 120 which undergoes loss of nitrogen to form azine 118 (Eq 66)

70 (CH,)sSn^ ^ 70 [70]' (D^C—N—N— C—N—N 1 18 (66) -Ng n(CH3)3 120

photochemically.

In an effort to learn more abouts its behavior, 70 was photolyzed in

cyclohexene. The purpose of this experiment was to determine if [70}* and/or

71 as generated might react with the jc-bond of cyclohexene to form

cyclopropanes 121 (Eq 67). Cyclopropanation products 121 are not 42

121 hv 7 0 + 0 (67) (^ 143)3811I., ^ = N —N = c f / C6^5rH Sn(CH3)3 118

observed; only azine 118 (51 %) was Isolated. Similarly, photolysis of 70 in ethyl vinyl ether yields azine 118; cyclopropane 122 is not found (Eq 6 8 ).

CH3CH2O, V<,Sn(CH3)3 CeHs 122 70 . (68 ) \ -Ng

(CH3)3Sn^ ^g H g ‘^ = N —N = c ! C s H / \n ( C H 3)3 118

Thus the results from the previous photolyses of 70 do not establish that carbene 71 is generated.

The thermal behavior of 70 was then studied. Detection of 115 (Eq 61), its dimer 117 or cyclopropane 116 (Eq 61) would suggest that carbene 71 is formed. Solutions of 70 in benzene were thus pyrolyzed over quartz chips at temperatures ranging from 175-500 °C under flowing argon. The pyrolysate was collected at -78 OQ. In all cases black material was deposited in the 43

pyrolysis tube and the collection flask. At elevated temperatures (> 425 °C), a

metallic (tin) mirror is observed on the inside of the pyrolysis tube. There is no evidence for formation of 115,116, 117 or any other tin derivatives. The

appearance of the tin mirror indicates removal of the trimethylstannyl group at

high temperatures. Flash vacuum pyrolyses of 70 over the same temperature ranges give similar results. When 70 is refluxed (160 °C) in cyclooctane for 3h the products obtained are azine 118 and diphenylacetylene

(123). Furthermore, when 70 is decomposed thermally in a mass spectral gas

chromatograph instrument with the injection port at 260 OC, the products that

could be identified are benzonitrile (124) and diphenylacetylene (123). These

observations suggest that 70 undergoes a thermal [3+3]-cycloaddition with

elimination of nitrogen to give azine 118. Formation of benzonitrile (124) can

be rationalized by the removal of trimethylstannyl groups and cleavage of the N-

N bond of azine 118. Diphenylacetylene could possibly be formed by removal

of the trimethylystannyl group from 70 to form the diazo radical 125 which upon

dimerization with another phenyidiazomethyl radical loses two equivalents of

nitrogen (Eq 69).

1 1 8 ------^ CgHg— CN -2 0Sn(CH3)à ■'24

70 (69)

1 2 5 U" ÎI" CgHg—C 0 CgHg— 0 —0 — CgHg - OSn(CH3)3 1 2 5 - 2 N2

CgHgC=CCgHg 123 44

It Is emphasized that intense effort and much time was given to study of the thermolysis of 70. Conditions could not be found however such that the primary reaction processes could be effrectively investigated.

In summary, photolysis of 70 in benzene, cyclohexene and ethyl vinyl ether produces azine 118 and there is no evidence for the formation 115, its dimer 117,116, or cyclopropanes 121 and 122. Azine 118 Is also formed upon thermolysis of 70. Additionally, removal of the trimethylstannyl group occur thermally to produce 123 and 124. In a later section it will be shown that carbene 71 and/or carbenoid can be effectively generated by rhodium(ll) acetate catalyzed decomposition of 70.

Rhodium(ll) Acetate Catalyzed Decomposition Reactions of

Phenyl(trimethylstannyl)dlazomethane (70)

As discussed earlier phenyl(trimethylstannyi)diazomethane (70) is quite

stable thermally. Diazo compound 70 can be refluxed in petroleum ether

(bp 60-90 OQ) for at least 24h without any apparent decomposition. The thermal

stability of 70 in solution suggests that some type of catalyzed process is

necessary for it to function effectively as a carbenic and/or carbenoid reagent.

Study was then directed to the behavior of 70 with rhodium acetate dimer in the

presence of varied substrates.

Rhodium(ll) acetate is an exceptionally effective catalyst for a wide

variety of reactions of diazo compounds.'^^ Rhodium(ll) acetate is a dimer with

a rhodium-rhodium single bond and four acetate ligands symmetrically attached

to the two rhodium atoms (Fig 4). Each rhodium atom has one-free unhindered 45

CHa

Figure 4. Structure of Rhodium(ll) Acetate

coordination site. Addition of rhodium acetate dimer to a diazo compound is beiieved to cause loss of nitrogen and production of an electrophilic metal- stabilized carbene (Fig 5).48 The metaliized carbene (carbenoid) reacts with

HoC-

Flgure 5. Rhodium(ll) Acetate Carbene Ylide 46

electron rich substrates resulting in transfer of the carbene moiety.

A study was first made of the behavior of phenyl(trimethylstannyl) diazomethane (70) in the presence of catalytic amounts of rhodium(ll) acetate

(4 mole %). In dichloromethane 70 is converted by rhodium(ll) acetate in 6 h to bis(trimethylstannyl)benzal azine (118, 95 %, Eq 70).

2 , 0 (70) -Ng CgH / Sn(CH3)3 1 1 o

The physical properties of azine 118 have been discussed in an earlier section.

A mechanistic rationaie for formation of azine 118 is as follows.

Rhodium(ll) acetate reacts with the nucleophilic carbon of 70 with elimination of

nitrogen to give rhodium ylide (carbenoid) 126. This carbenoid then adds to

70 to give intermediate 127 from which expulsion of rhodium acetate dimer

produces azine 118 (Eq 71). Formation of azine 118 by decomposition of 70

O 6^5 Rh 2(oCCftX / II V O 70 iv (H3CC0)4 Rhg—c0 + 70

(71)

, M , G /tf ® /-X >(CH3)3 ^ H3C CO j 4 Rhg — —N— ------to- -j Q 47

with rhodlum(ll) acetate is consistent with a study by Shankar and Shechter in that secondary aryldiazoalkanes are converted by rhodium(ll) acetate to the corresponding azines.49

Recently, Doyle et al have reported remarkable facility for Si-H insertion by metal carbenoids. In their study diazo esters and diazo ketones were decomposed by rhodium(ll) acetate in the presence of triethylsilane to yield a-silyl ketones (Table 6 ). A study has been presently made of the behavior of 70 when decomposed catalytically by rhodium(il) acetate in the presence of varied silanes. The following describes the results of this investigation .50

ta b le 6. Synthesis ofa-Silyl Esters and Ketones by Rhodium(ll) Acetate-Catalyzed Decomposition of Diazo Compounds in the Presence of Triethylsilane

Diazo Organo- Product Compound silane % Yield

NgCHCO^CHgCHg (CHyC%SiH (CK^CHglbSiCliCO^CHgCh^ 94

NgCHCOCfCI^ (CI^CHgiîSiH (Cf^CHaijSiCttCOCfCHg)^ 89

NgCHCOQI^ (CHgC^SiH (Ck^CHglliSiCliCOC^tt 95 NgCHCOCl^CBl^ (CHjCHalbSiH (Ch^CH2)3SiCliCOCH2CBt^ 85 NaCfChyCOCçt^ (CI-^C^SiH (CI^CH2]bSiCH(Cli)COC6Ht 90

Upon of addition of 70 in dichloromethane in 6 h to rhodium(ll) acetate in

excess triethylsilane (128), a-triethylsilyl-a-trimethylstannyltoluene (129, 85 %,

Eq 72) is formed. The IR spectrum of 129 exhibits bands characteristic 48

70 + (CHgCHgj^SiH ------^-- CgHg—CrH c~ C6 —Sn(CH — S n(CH,)a3)3 (72) 128 i 1 2 9

for Si-C absorptions (770 and 1245 cm -1). The ‘*H NMR of 129 shows signals for C-H protons attached to the alkyl portions of the silyl and stannyl groups.

Also the methine proton absorption is a singlet at 2.01 ppm. Further, the 13C-

(Dept) NMR exhibits seven distinctive signals accounting for the different carbons in 129. Both the mass spectral and elemental analyzes are consistent with the assigned structure.

Triisopropylsilane (130) was than found to react with 70 in the presence of rhodium(ll) acetate to give a-triisopropylsilyl-a-trimethylstannyltoluene

(131, 76 %, Eq 73). Benzal derivative 131 was characterized by its 1 H-NMR,

f(CH.CH,CH3)3 70 + (C1tC1^C%SIH ------CeHs— Ç—Sn(CH3>3 (73) -No 130 ^ H 131

13C-NMR(Dept), mass spectral and elemental analyses.

Similarly, cyclohexyldimethylsilane (132) and dimethylphenylsilane

(134) containing rhodium(ll) acetate (4 mole %) react with 70 to yield the

corresponding a- trialkyl-a-trimethylstannylbenzal derivatives, 133 (Eq 74) and

135 (Eq 75), respectively. Stannylsilanes 129, 131, 133 and 135 are 49

Si(CH3)2CsHii Rh2(0CCh^)4 70 + (CHjJ^C^HiiSiH CeHs— Ç—Sn(CH3)3 (74) -Ng 1 3 2 H 133

Si(CH3)2CeH5 (^^(oCCHaX 70 + (C%C^hySiH CeHs— Ç—Sn(CH3)3 (75) 13 4 H 135

liquids at room temperature which can be purified using column chromatography (silica gel) and are moisture insensitive. These experiments demonstrate the generality of using rhodium(ll) acetate to decompose 70 in the presence of varied silanes to produce a-trialkylsilyl-a-trimethylstannylbenzal derivatives. Concurrent formation of bis(trimethylstannyl)benzal azine 118 lowers the yields of the isolated products (Table 7).

Table 7. Synthesis of o-Sllyl-a-trimethylstannyltoluene Derivatives by Rhodium(ll) Acetate-Catalyzed Decomposition of 70 in the Presence of Organosilanes

Diazo Organosilane Product % Yield Compound

70 (CHgCHgl^SiH (CHgCHgj^SiCH^SnfCltk 84

70 (CHgCHgCHalljSiH (CH)CH2CH2))SiCH%Sn(CI-y^ 76

70 (CH3)^CbH„SiH (CH3)^CsHiiSiHqitSn(CH 3)b 83

70 (CHgj^C^H^SiH (C%SiH(Q%Sn(C% 79 50

A mechanistic rationale for Si-H insertion by rhodium(ll) acetate catalyzed decomposition of 70 is illustrated in Fig. 6 . It is presumed that

(CHskSn 0 _>iR 3 : 0 C e H/ R/O ' '

Figure 6 . Insertion of Carbene 71 Into a SI-H Bond

carbene 71 inserts into Si-H bonds as a singlet by a concerted, three centered

process. This Interpretation is consistent with recent observations that

unsaturated carbenes undergo intramolecular Si-H insertion with retention of

configuration (Fig. 7).51

SIR,

Figure 7. insertion of Unsaturated Carbene Into a SI-H Bond

Cyclopropanations of olefins by diazo compounds using transition-metal

catalysts is an important synthetic transformation.52 Such catalytic reactions

have frequently supplanted thermal and photochemical methods. The behavior

of phenyl(trimethylstannyl)diazomethane (70) when decomposed by

rhodium(ll) acetate in the presence of varied olefins thus became of interest. 51

The methodology employed for the study with olefins is similar to that described earlier for trialkylsilanes. Thus, 70 in dichloromethane is added over

6 h to a mixture of olefin and rhodium(ll) acetate (4 mole %) in dichloromethane.

The first olefin investigated was styrene (136A) in an attempt to prepare cyclopropane 137A (Eq 76). The reaction product shows no evidence for cyclopropane 137A; only azine 118 (72%) is isolated. Cyclopropane

7 0 + (76)

136A

;C=N—N =C

formation with olefins is known to be competitive with production of azines when

using metal-catalyzed decomposition methods.53 However, the total absence

of 137A is surprising. In contrast, phenyldiazomethane (76) gives

cyclopropanes in reactions with styrene (38 %), 1-hexene ( 6 %),

cyclopentene (6 %) and 2-methyl-2-butene (23 %) in the presence of

rhodium(ll) acetate.54 52

Further, 2-methyl-2-butene (136B) and cyclopentene (136C) are not oyclopropanated by 70 and rhodium(ll) acetate; only azine 118 (70 %) Is isolated. The failure to form any cyclopropane derivative suggests that a more

reactive olefin is needed. Thus, methylenecyclohexane (136D) and

methylenecyclopentane (136E) were investigated. Again, only azine 118 (70

%) is formed (Eq 77).

137(A-E) (77) R2' R3 -Ng 136(A-E)

CsHs ^ n (C H 3)3 136A:R^ = H, R^ = H, R^ = Cgft ^C = N —N = c f 136B: R^ = CHg r2 = CHg, R® = CHg (CH3)3Sn''^ ^ ^ ^ % H 5 136C: R’ = H, R 2 and R® = (CHgCHgCHg) 11 8 136D: R^andff = [CH2(CH2)bCH2l , R® = H 136E: R’ and R^ = [CH2(CH2)^CH2], R® = H

Doyle has reported that cyclopropanations of vinyl ethers with diazo

compounds and rhodium(ll) acetate are synthetically u s e f u l .5 5 The behavior of

phenyl(trimethylstannyl)diazomethane (70) and oxyvinyl derivatives in the

presence of rhodium(ll) acetate was thus investigated.

The oxyvinyl derivatives presently studied are ethyl vinyl ether (138), n -

butyl vinyl ether (140), dihydropyran (142), vinyl acetate (144) and 1,1-

dimethoxyethylene (146). In all cases, 70 in dichloromethane is added to the 53 olefin and rhodium(ll) acetate (4 mole %) in dichloromethane at room temperature.

Addition of 70 to ethyl vinyl ether (138) occurs smoothly as catalyzed by rhodium(ll) acetate to give (E)-2-ethoxy-1-phenyl-1-trimethylstannylcyclopropane (139, 80 %, Eq 78). Cyclopropane 139 has 1 H-NMR

CH3CH2Q

Ph,{oècH,), CebTs \ (78) h '' \ -N, 138 8 0 (0113)3 139

for aromatic protons and tha appropriate signals for ethoxy , trimethylstannyl

and cyclopropyl ring protons. The 1^0- NMR(Dept) shows ten signals, as

expected, for the different carbons in 139 Also the mass spectral (exact mass)

and elemental analyses are consistent with the assigned structure.

The stereochemistry of 139 is of interest since both 1 H-NMR and

"13Q-NMR indicate that only one pair of diastereoisomers is formed. A NOE

experiment with 139, in which the trimethylstannyl group is irradiated to detect

neighboring groups, shows enhancement for the methine group attached to the

cyclopropane ring. This result indicates that the trimethylstannyi group and ring

methine hydrogen are on the same side of the cyclopropane ring providing

evidence for the assigned E-stereoisomer (139). Thus, formation of 139

occurs diastereospecifically. Of note is that azine 118 is also formed in this

experiment. 54

Reaction of 70 and n -butyl vinyl ether (140) as catalyzed by rhodium(ll) acetate yields (E)-2-butoxy-1-phenyl-1-trimethyistannyicyclo- propane (141, 82 %, Eq 79). The cyclopropane is assigned as 141 on the

CH3(CH2)2CH2Q

CH3(CH2)2CH20 H RhafoCCHbl 70+ ^C=C - / \ H H - Ng 140 8 0 (083)3 141

basis of its spectral properties and elemental analyses. Again, distereo- specificity is observed to give the E-stereoisomer as indicated by a NOE experiment.

Since both ethyl vinyl ether and n-butyl vinyl ether undergo

cyclopropanations diasterospecifically it was of interest to investigate

addition to the cyclic vinyl ether dihydropyran (142). Reaction of

142 with 70 and rhodium(M) acetate is found to give (E)-2,4-

dihydropyranyl-1-phenyl-1-trimethylstannylcyclopropane (143, 71 %, Eq 80).

0 Rh2(0CCktX 70 + (80) 0 -Ng 1 4 2 (083)380 143 55

Interestingly, the E-stereoisomers are again formed as demonstrated by

NOE. Furthermore, the H-NMR and ‘•Sc-NMR of 143 indicate that no other diastereisomer is formed.

To learn more about electronic effects on the reactions of 70 with olefins studies were made of vinyl acetate (144) and of 1,1-dimethoxyethene (146).

Vinyl acetate (144) is much less and 146 is much more electron rich than are the previously studied alkoxy-substituted ethers: 138,140 and 142. When

144 is used under conditions similar to those successful for 138,140 and

142, no cyclopropanation product (145) is obtained (Eq 81); azine 118 is the

u CHgCQ

Sn(CH3)3 (81) 145 \ -Ng 1 4 4

CeHs ^n(C H 3)3 jC=:N—N = c f (CH3)3Sn*‘^ % H e 1 1 o

only product isolated. Cyclopropanation of 146 occurs however in high yield to give 2-dimethoxy-1-phenyl-1-trimethylstannylcyclopropane (147 92% , Eq

82). The "I H-NMR, 13C-NMR(DEPT), mass spectral and elemental analyses are consistent with the structure assigned for 147. These experiments 56

0 CH3Q CHgO. H Rh 2 (0 CC^^)^ 70 + (82) CH3 O CH3 O H -N2 1 4 6 Sn(CH3)3 147

demonstrate the need for an electron-rich olefin in order for cyclopropanation to occur with 70 and rhodium(ll) acetate.

A mechanistic rationale which accounts for the diastereoselectivity in the above experiments is of interest. An elaborate mechanistic model has been proposed by Doyle for rhodium(ll) acetate catalyzed reactions of ethyl diazoacetate (150) and phenyldiazomethane (76) with vinyl ethers.56

According to Doyle, cyclopropanes result from association (148A and I486) of the olefin %-bond with the electrophilic center of the métallo carbene followed by

c-bond formation with backside displacement of the catalyst (Eq 83).

H H LnM U,M- -M L A H H R Z — 149A LnM=C: H H 148A (83) R H H R LnM LpM--- H -IC h 149B

148B 57

When transition states Tc and Tt are nearly equal in energy then the difference in stabilities of the 7c-complexes (148A and 148B) determine which stereoisomer (Z or E) product is favored. However, when transition states Tc and Tt differ as result of interactions between groups R and Z, then the stereoisomer (Z or E) derived from the lower transition state energy will be favored. Thus, in the absence of predominant steric effects between R and Z in the transition states: Tq and Tt the Z isomer is predicted to be favored since the jt-complex 148A is less hindered. Thus the Z isomer 149A is the predominant product (Table 8 ). As the size of the R group on the olefin

Table 8 . Rhodium(ll) Acetate Catalyzed Reactions of Phenyldlazo- methane(76) with Representative Olefins

cis / trans Oiefin % Yield (Z/E)

n -butyl vinyl ether 92 2.5 ethyl vinyi ether 54 3.0 styrene 38 3.3 2-methyi -2 butene 23 12 vinyl acetate 7 3.8 1-hexene 6 0.9 cyclopentene 6 1.6 3-methyl-1-butene 4 0.6

is increased, kc and the Z / E ratio of the cyclopropyl products are decreased 58

Stereochemical preference for the formation of E-cyclopropyl isomers in catalytic cyclopropanations of olefins with ethyl diazoacetate (94) appears to be an exception to the previous model. It has been however proposed that since the carbonyl group is highly polar, there could be interaction between the nucleophilic oxygen of the carbonyl group and developing positive charge on the olefin in the %-complex formed from the metallocarbene and olefin (Eq 84 ).

H - M o C H , C H 3 * W (84) 94 " " t

0 (HgC CD) 4Rh 2 HgC 00)4Rh2 C—OCH2CH3 T^C-OCHaCHg

?\ " R H (HgC CD)4Rh2 H C = 0 ■Rh2(0CCh^)4 I OCH 2 CH 3 CH3CH2O

Electronic stabilization therefore is possible in the transition state leading to

E-cyclopropane (150) Thus, Doyle's mechanistic model can be made to 59

account for the predominant Z stereoselectivity observed for reactions of ethyl diazoacetate (94) and rhodium(ll) acetate with olefins (Table 9). What

Table 9. Rhodium(ll) Acetate Catalyzed Reactions of Ethyl Diazoacetate ( 94) with Representative Olefins

trans / cIs Olefin % Yield (E/Z)

n -butyl vinyl sthsr 64 1.7 ethyl vinyl ether 88 1.7 styrene 93 1.6 cyclohexene 90 3.8 dihydropyran 91 6.5

remains is to account for the diastereospecificity observed for the rhodium(ll) acetate catalyzed reactions of 70 with vinyl ethers in the present research.

The cyclopropanation reactions of phenyl(trimethylstannyl)diazomethane

(70) with ethyl vinyl ether (138), n-butyl vinyl ether (140) and dihydropyran

(142) give only E-cyclopropanes 139,141 and 143, respectively. The

(trimethylstannyl and the alkoxy groups are on opposite sides of the cyclopro pane ring). Thus, according to the previous mechanistic model the interactions of the bulky trimethylstannyl groups and the alkoxy groups raise the energies of

T q s o much that the reactions proceed exclusively through Tt to form only the E- cyclopropanes 152B (Eq 85) (See Appendix B for further discussion). 60

H O RQH ^HgCCO^^ Rhg— C © Sn(CH3)3 »X. 126

V ° " 6^5 O 6^5 n o o y < k / HgC OOj^Rhp' - r h m (HgG CO);Rh«Rho C î(î Sn(CHg )3 ^ ^ S n ( C H 3)3

H H H ^ O R 151A 151B (85)

OR OR

"^Rh2(0CCH3X -Rh. (oCCHa)^

H ,Sn(CH3)3

RO Sn(CH3)3 RO •CgH, 152A 152B 61

The Relative Reactivities of Triethyisiiane and Ethyl Vinyl Ether Towards Phenyi(trimethyistannyi)diazomethane/Rhodium(ii)Acetate

Study has been made of the relative reactivities of phenyl-

(trimethyistannyl)diazomethane (70) / rhodium(li) acetate with respect to

Insertion Into the Si-H bond of triethyisiiane (128) and addition to the C-C double bond in ethyl vinyl ether (138) at room temperature. The experimental method involves determination of the molar yields of 129 and 139 obtained from reactions of 70 / rhodium(il) acetate with excess triethyisiiane and ethyl vinyl ether in equimolar quantities. The actual experiments were conducted essentially identically with that described previously for 70 and rhodium(ll) acetate with silanes and electron-rich olefins. The relative rate constant is calculated from ki / k2 = (Pi / P2 )(Ql / 02). in which Pi / P 2 is the mole ratio of the reaction products from triethyisiiane (128) and ethyl vinyl ether (138) and

Q l / 0 2 is the mole ratio of triethyisiiane (128) and ethyl vinyl ether (138).

It has been found in the competitve experiment that 60 % a-triethylsilyl-a- trimethylstannyltoluene (129) and 24 % (E)-2-ethoxy-1 -trimethylstannyl-1 - phenylcyclopropane (139) are formed. The relative reactivity of triethyisiiane

(128) to ethyl vinyl ether (138), ki28 /k i 3 g , is thus 2.5 at room temperature.

This competitive study indicates that Si-H insertion of 70 / rhodium(ll) acetate is 2.5 times faster than addition to the C-C double bond of ethyl vinyl ether. The results of competitive studies for Si-H insertion and addition to the

C-C bond in cyclohexene for ethyl diazoacetate and dichlorodiazomethane are summarized in Table 10.57 The relative reactivities are therefore dependent on the diazo compound investigated. 62

Table 10. Relative Reactivities of Diazo Compounds for Si-H insertion and addition to C-C Double Bond

Diazo Compound Reactants ^ silane ^ ^ olefin

/ / CgHg — C— Sn(CH3)3 (CI-^C%SiH /H gC ^cr 2 .5 ' OCH2CH3

II H— C— C— OCH2CH3 5 .8

li^ Cl— C—Cl (Ch^CH^SiH y 0.8

Synthesis and Chemistry of Lithium Phenyidiazomethane (72)

Methods of preparation and knowledge of the chemistry of electrovalent

metallized salts of diazomethyl compounds are as yet quite limited.

Investigation has been presently made of synthesis and the reactions of lithium

phenyidiazomethane (72). Choice of 72 for study was made because of its

relationship with 70 and it is a model for a-lithiated diazo compounds which are

not highly delocalized and do not have a-hydrogen.

As have been described earlier, diazomethane (Eq 8 6 ), ethyl

diazoacetate (Eq 87) and trimethylsilyldiazomethane (Eq 8 8 ) may be 63

{*2 CHaU ^2 H—C—H . Qu H—C—U (86) 2

Îj2 0 „ .Buu N2 O

H—C—C—OC 2 H 5 . gjj|-| Li—C—C—OC 2 H 5 (8 7) 5

Ng Ng Il n -BuU II (CH3)3Si— C—H ------► (CH3)3Si— C— U (88) -BuH 3 3

successfully deprotonated with alkylllthium reagents. Examples of the synthetic utility of lithium diazomethane (2), lithium ethyl diazoacetate (5) and lithium trimethylsilyldiazomethane (33) are illustrated in Equations 89-91.

f ^ f 2 Li— C—H + 8 R3MCI _ 2 |_jQ| R3M—C—MR3 + H—C—H

2 13

M = Ge, R = C6Hs (44%) M = S n, RzzCgHg (56%)

M = S n. R = CH3(80%)

Li— C—C—OC2H5 . LjQi (CH3)3M—C—C—OCgHg (90) 5 11

M = Si (52 % ), Sn (50 % ), Pb (10 %) 64

îl^ î|2 RX + Li“ C— Si(CHa)3 ------;----- ► R—C— Si(CHa)3 (91) 33 3 4

RX = CeHgCHaCK?? % ), CH3(CH2)gBr(65%),

CH2= C H (C H 2)gl( 7 2 %) and C6HsO(CH2)3Br(62%)

A major complication in deprotonation of diazo compounds by strong bases is attack on terminal nitrogen of the diazo groups to give hydrazones upon acidification. Thus diazoethane and methyllithium yield the

N-methylhydrazone of acetaldehyde (153) as in Equation 92.58

H LI - UOH H H 1 5 3

Similarly, diazo(tetraphenyl)cyclopentadiene and phenyllithium after acidifi cation afford tetraphenylcyclopentadienone phenylhydrazone (154, Eq 93).59

;U N—N' (93) 2. HoO

154 65

Further, Grignard reagents add to terminal nitrogen of diazomethane (Eq 94) and diphenyldiazomethane (Eq 95) to form hydrazones 155 and 156,

h X h '>=N-<" '''' 155

11^ CgHgMgBr CgHg ^CgHg HgO CrMs /CgHg CgHg— C—CsHg ------► C = N —N -MgBr(OH) C = N —N (95) CgHg/ MgBr CgH/ 156

respectively, upon acidification.60

Of further note is that diazomethane (157), ethyl diazoacetate (94) and trimethylsilyldiazomethane (14) undergo rapid deuterium exchange of a-

hydrogen upon reaction with deuterium oxide in the presence of catalytic quantities of deuteroxide bases.61 The acidities of 157, 94, and 14 are not

known but it is clear that exchange into 158 does ûûI occur by simple

acid-base processes (Eq 96). Apparently, diazomethane (158) is converted to

«2 ©OP Mz DjO H—C—H ------H— ------(96) 157 -DOH QOD

Mz O O D Na DgO N, H - C - D ------D - C © * ------D - C - D - DOH 0O D 158 66 dideuteromethane (158) by terminal attack on nitrogen (Eq. 97).

N: Q o D m V H_c—H HgC—N=N—OD " HgCD—N=N—OD 157 -OD© ©OD

0 O D © ^2® HCD—N=N—OD — HCDg—N=N—OD (97) - DOH © O D

The questions remain however as to whether varied primary diazoalkanes can be efficiently deprotonated by appropriate organometaliic bases and whether the conjugate bases of the diazo compounds can be conveniently used for meaningful syntheses. In a prelirhinary investigation in this laboratory

by Sheiue, reaction of phenyidiazomethane with alkyllithiums in the presence of tetramethylethylenediamine (TMEDA) was reported to give results which

appear promising for synthesis of lithium phenyidiazomethane ( 7 2 ).62 Thus

phenyldiazomethyllithium (72) was reported to be converted by f-butyllithium at

-78 °C in ethyl ether containing TMEDA to lithium phenyidiazomethane (72)

which reacts with trimethyisilyl chloride, triphenylsilyl chloride, triphenylgermyl

chloride and triphenylstannyl chloride to yield phenyl(trimethylsilyl)diazo-

methane (75 %), phenyl(triphenylsilyl)diazomethane (34 %), phenyl(triphenyl-

germyl)diazomethane (35%) and phenyl(triphenylstannyl)diazomethane (55%), 67

respectively. Further, lithium p-chlorophenyldiazomethane, prepared from p- chlorophenyldiazomethane and f-butyllithium / TMEDA / ethyl ether, was reported to react effectively (37-71 %) with trimethyisilyl chloride, triphenylsilyl chloride, triphenylgermyl chloride and triphenylstannyl chloride to give the correspondindg p-chlorophenyltrisubstitutedmetallodiazomethanes.

Unfortunately, infrared absorptions for diazo groups were not reported for the organometaliic diazo compounds and the melting points, when given, did not always agree with the literature. Furthermore, Shieue's study showed that reproducibility of the preparative results was difficult. The results from Shieue's study suggested that a more thorough investigation should be made in order to determine the proper experimental conditions to make the method more reliable.

An intensive investigation of lithiation of phenyidiazomethane using varied alkylllthium reagents was thus conducted. In the present study: methyllithium, n-butyllithium, sec-butyllithium and ferf-butyllithium,respectively, with and without TMEDA, were added to phenyidiazomethane in attempts to prepare lithium phenyidiazomethane efficiently. These experiments were performed at -78 °C and -100 °C and inverse addition methods were also tried. To the various reaction products were added trimethylstannyl chloride, triphenylstannyl chloride or triphenylsilyl chloride. In the present experiments there is no evidence that organometaliic diazo compound are formed (Eq 98). 68

N, I.R'U Na

CgHg—C—H CgHg C—MRg (98) 2 .R 2gMCI

R^ =CHg, n-Bu, sec-Bu, tert-Bu (TMEDA) R^k/l = (C% Sn, (CgH^Sn, (CgfUSi

The lack of success using phenyidiazomethane and varied alkyllithiums led to search for a reliable method for preparing 72. Study was then initiated of exchange reactions of phenyl(trimethylstannyl)diazomethane (70) and n-butyllithium. Indeed, when n-butyllithium is added to 70 at -78 °C, the mixture turns brown immediately with formation of lithium phenyidiazomethane

(72, Eq 99). Upon addition of triphenylsilyl chloride the reaction mixture gives a new intense IR band for a diazo group and crude phenyl(triphenylsilyl)diazomethane (159) is formed . Investigation was thus

No Ng i r n -BuU II CgHg— C—Sn(CH3)3 ------CgHg— C— Li (99 ) 70 - n -BuSn(CH3)^ 7 2

N (Cgl^SiCI 2 CgHg— C-Si(CgHs)3 ■ LiCI 159

made of the synthetic usefulness of 72 generated as above. Triphenymetallo chlorides were used as electrophiles for reactions with 72 in order to obtain solids that can be easily handled. 69

Addition of n-butyliithium to 70 at -78 °C followed by triphenylsilyl chloride gives crystalline phenyl{triphenylsilyl)diazomethane (159, 48 %, Eq

99) preparatively. Diazo compound 159 is of proper melting pointas and exact mass and has an IR diazo band at 2045 cm"1. As expected the 1H-NMR of 159 shows signals only in the aromatic region.

Reactions were then extended satisfactorily to triphenylgermyl chloride, triphenylstannyl chloride, triphenylplumbyl chloride and diphenyi- chiorophosphate [(CeH 5 )2 POCI] to yield phenyl(triphenylgermyl)- diazomethane (160 , 67 %, IR; C=N 2 , 2040 cm’"'em), phenyl(triphenylstannyl)diazomethane (161, 45 %, IR; C=N2, 2020 cm-"*), phenyl(triphenylplumbyl)diazomethane (162, 42 %, IR; 2005 cm’1) and diphenylphosphinyl(phenyl)diazomethane (163, 65 %, IR; C=N2, 2075 cm’1), respectively.

CgHg—C—Ge(C6Hg)3 CgHg— C—SnfCgHg); 160 161

11^ II II CgHg-C-Pb(CgHg)3 CgHg— C— P (CgHg), 162 1 6 3

Products 160,161,162 and 163 have proper mass spectral, IR and I H-NMR

analyses, 160 and 163 have melting points64 which correspond to literature values and 161 and 162 give satisfactory carbon and hydrogen analyses.

The behavior of 72 with phenylmercuric chloride was then investigated.

Surprisingly the product is 3,6-dipheny-1,2,4,5-tetrazine (164, 6 6 %, Eq 100); 7 0

Cst^HgCI N—N. CgH g —^ CgH -UCI N = N li^ 1 6 4 CgHg— C— Li (100) 72 C6^^HgCi CgHg— C— HgCgHg -UCI 185

phenylmercurio(phenyl)ciiazomethane (165) could not be detected during reaction. Tetrazine 164 is identified from its melting p o i n t , 65 its (simple) 1H-

NMR and its mass spectrum The mechanism of formation of 164 in the present experiment is speculative as will be discussed.

3,5-Diphenyl-1,2,4,5-tetrazine (164) has been previously prepared by thermolysis or photolysis of 5-phenyltetrazole ( 1 6 6 ).66 it was presumed that

164 is formed by conversion of 166 to phenylnitrilimine 167 which undergoes

1,3-dipolar cyclodimerization with elimination of hydrogen as in Equation 101.

CgHg 3 0 © O CgHg—C=N—N— H - CgHg— C—N— N— H

V - 1 6 7 166 (101) H

N-N^ N—N. CgHg— A— CgH, C gH g —^ CgH N-N -Hg N = N H 164 71

In the present experiment reaction of 70 with phenylmercuric chloride might have resulted in phenymercuric(phenyl)nitrilimine (168) and/or phenylmercuric(phenyl)diazomethane (165). Rapid 1,3-cyclodimerization of 168

(Eq 102) or 165 (Eq 103) with loss of phenylmercury [Hg 2 (C e H 5 )2 ] rationalizes the present synthesis of tetrazine 164.

(Cglt)HgCI L _ 0 (o CgHg— C— LI jCgHg— C=rN— IN- -HgCgHg 72 -LICI 1 6 8 HgCgHg (102) N—N N—N. CeHs——^ CgH CsHs— \ ^— CgH N—N - HgafCgf^ N=N CgHgHg 1 6 4

o CgHg— Ç— HgCgHg % CeH5^ N = N HgCgHg CgHg— 0 —HgCgHg 0 |!j N CgHgHg N=N CgHg 165 (103) N—N. CgHg — ^ ^ — CgH H 92(CgH s)2 N=N 1 64 72

The success in preparing organometaliic diazo compounds from 72 and tiiarylmetallo chlorides led to study of the possible synthesis of azibenzil (169) by reaction of benzoyl chloride (170) with 72 (Eq 104). Addition of benzoyl

?[ CgHs—C-CI 0 No 1 7 0 II \f 7 2 ------CgHg—C—C—CgHg (104) 1 6 9

chloride (170) to 72 at -78®C results in rapid displacement. The reaction mixture however shows no IR absorption for a diazo group and 189 is not detected. Inverse addition of 72 to benzoyl chloride (100 equiv) in great excess however gives an immediate yellow colored mixture with chromatographic

(Rf vaiue) properties and IR absorptions (C=N 2 at 2080 cm-1 ) identical with

169. Work-up of the reaction product yields 169 contaminated with benzoyl chloride (170). The method of synthesis of 169 as yet perfected is not highly practical because of the need for excess benzoyl chloride.

The method was then extended to reactions of 72 with p-chlorobenzoyl chloride (171) and p-trifluoromethylbenzoyl chloride (172). Additions of 171

and 172, respectively, to 72 give mixtures which do not show IR absorptions for

diazo groups (C=N 2 ). Work-ups of the reaction mixtures yield crystalline

products assigned as p-chlorobenzoylbenzalazine (173, 42 %) and p-

trifluoromethylbenzoylbenzal azine (174, 43 %), respectively. 73

Il II H C-CeHg-CI-p H C-CgHgCFa-i JO=N—N=qT J1C=N—N=cf C0H5 UgHg CgHg i^gHg 173 17 4

Azlnes 173 and 174 are assigned on the basis of their exact masses, carbonyl absorption and their IR, 1 H-NMR, 13C-NMR and caiton, hydrogen and nitrogen elemental analyses. In theory four possible geometric Isomers could be formed for azine 173 and 174 (Figure 8 ). The 1 H-NMR and 13C-NMR of 173 and

CgHg ÇsHs

C—CgHg-Z ^C—C—CgHg-2

"'6^5 ^

H" A . CgHg B

ÇgHg-Z ÇsHg-Z

Ç = 0 0 = 0 ^C—CgHg ^ 0 —CgHg N-N m-N CgHg— H—

A igHgng D

Figure 8 . Possible Geometric Isomers of Azines 173 and 174 74

174 suggest that only single geometric isomers are obtained. A possible

mechanistic route to 172 and 173 is illustrated as follows (Eq 105).

. N CgHg — 0 — Li + Cl— C — CgHg-Z II -UCI CgHg— C—C— CgHg-Z

Li— O CgHg-Z 7 2 vN 1.H2O (105) / 2.-N, C«H8^5 \;«H6^5

CX CgHg-Z H y r = N —N = c : Z = CI orCFg / C6^5rH 6^5 SUMMARY

Study has been made of synthesis and chemistry of phenyl(trimethylstannyl)diazomethane (70), its subsequent carbene (71) and or carbenoid and lithium phenyidiazomethane (72). A major purpose for this research was to gain knowledge concerning a-metallo diazo compounds.

Phenyl(trimethylstannyl)diazomethane (70) is obtained in 80 % yield from diethylaminotrimethylstannane and phenyidiazomethane in refluxing petroleum ether (bp 60-90 °C). Diazostannane 70 undergoes 1,3-dipolar cycloadditions with N-phenylmaleimide and acrylonitrile to give the a 2- pyrazolines: N,3-diphenyl-2-pyrazoline-4,5-dicarboximide (83) and 3-phenyl-2- pyrazoline-5-carbonitrile (87), respectively. Cycloaddition reactions of 70 with

1,4-naphthoquinone, dimethyl acetyienedicarboxylate and diphenylacetylene yield 3-phenyl-1-(trimethylstannyl)-1H-benz[f]indazole-4,9-dione (93), dimethyl

3-phenyl-1-trimethylstannylpyrazole-4,5-dicarboxylate (101) and 3,4,5- triphenylpyrazole (105), respectively. Also reaction of 70 with three equivalents of bromine, results in removal of nitrogen and the trimethylstannyl group to give a,a,a-tribromotoluene (113). I Photolysis and thermolysis of 70 to generate 71 were Investigated.

When 70 is irradiated in benzene, cyclohexene and ethyl vinyl ether, bis(trimethylstannyl)benzalazine (118) is obtained. No evidence was found for methyl migration of the trimethylstannyl group to the carbene carbon in 71 to give stannene 115, its dimer 117 or C-H insertion into the methyl group to give

75 76 cyclopropane 116. Thermolysis of 70 yields azine 118 and diphenyl acetylene (123). Decomposition and removal of the trimethylstannyl group at high temperatures prevent more detailed study of 71 and 115,116 and 117.

Rhodium(ll) acetate catalyzed reactions of 70 were investigated.

Addition of 70 to rhodium(ll) acetate in dichloromethane gives azine 118.

Reactions of 70/rhodium(ll) acetate with triethyisiiane, triisopropylsilane, dimethylphenylsilane and cyclohexyldimethylsilane yield a-triethylsilyl-a- trimethylstannyltoluene (129), a-triisopropylsilyl-a-trimethylstannyltoluene

(131), a-dimethylphenylsilyl-a-trimethylstannyltoluene (133) and a-cyclohexyldimethylsilyl-a-trimethylstannyltoluene (135), respectively. Attempted additions of 70 to styrene, 2-methyl-2-butene, cyclopentene, methylenecyclopentane and methylenecyclohexane containing catalytic quantities of rhodium(ll) acetate yield azine 118. No evidence is obtained for addition of 71 to the olefins to form cyclopropanes. Reactions of 70/rhodium(|[) acetate in the presence of ether vinyl ether, n-butyl vinyl ether and dihydropyran yield only E- cyclopropanes: (E)-2-ethoxy-1-phenyl- 1-trimethylstannylcyclopropane (139),

(E)-2-butoxy-1-phenyl-1-trimethylstannylcyclopropane (141) and (E)-2,4- dihydropyranyl-1-phenyl-1 -trimethylstannylcyclopropane (143), respectively.

Studies of electronic effects on the reactions of 70 with olefins were

made of vinyl acetate and 1,1 -dimethoxyethene. No cyclopropanation product

is obtained for vinyl acetate; only azine 118 is obtained. Cyclopropanation of

1 ,1-dimethoxyethene occurs however in high yield to give 2 ,2 -dimethoxy- 1-

phenyl-1-trimethylstannylcyclopropane (147). The relative reactivities of triethyisiiane and ether vinyl ether towards 70 /rhodium(ll) acetate demontrate that the silane is 2.5 times more reactive than is the vinyl ether. 77

Attempts to prepare lithium phenyidiazomethane (72) by deprotonation of phenyidiazomethane with alkylllthium reagents: methyllithium, n-butyllithium, seo-butyllithium and ferf-butyllithium, with and without TMEDA at -78 and -

100 °C were unsuccessful. However, 72 can be obtained by destannylation of

70 with n-butyllithium. Reactions of 72 with triphenylsilyl chloride, triphenylgermyl chloride, triphenylstannyl chloride, triphenylplumbyl chloride and diphenylphosphinic chloride give the corresponding a-metallodiazo compounds; phenyl(triphenylsilyl)diazomethane (159), phenyl(triphenylgermyl)diazomethane (160), phenyl(triphenylstannyl)diazomethane (161), phenyl(triphenylplumbyl)diazomethane (162) and diphenylphosphinyl-

(phenyl)diazomethane (163), respectively. Phenylmercuric chloride and 72 however yield 3,6-diphenyl-1,2,4,5-tetrazine (164).

The behavior of 72 with acid chlorides has been investigated. Addition of 72 to benzoyl chloride gives azibenzil. Reactions of 72 with p-chlorobenzoyl chloride and p-trifluorobenzoyl chloride yield p-chlorobenzoylbenzalazine

(173) and p-trifluoromethylbenzoylbenzalazine (174), respectively.

Results from this investigation suggest that future reseach should be directed towards finding bases that can deprotonate diazomethyl compounds effectively. Also a better understanding of the chemical behavior of lithiated diazomethyl compounds is needed. Questions remain to be answered concerning whether diazo carbon or terminal nitrogen of diazomethyl anions react as the nucleophilic site for attack on varied electrophiles. Furthermore, additional knowledge of the photolytic and thermolytic behavior of a-metallo diazo compounds is warranted. EXPERIMENTAL

General information

Melting points were determined using a Thomas Hoover melting point apparatus. All melting points are uncorrected.

Bolling points are uncorrected and were determined during distillation at the pressures indicated.

Elemental analyses were performed by Microanalysis, Inc.,

Wilmington, Delaware.

Infrared spectra were obtained on a Perkin-Elmer 457 Grating Infrared

Spectrophotometer using the polystyrene 1601 cm'1 band as a standard.

Spectra of solid samples were taken as potassium bromide pellets and liquid samples were determined neat between sodium chloride plates or in solution cells.

Mass spectra were recorded on a Kratos DS-55 mass spectrometer at an ionization energy of 70 eV.

1 H-NMR spectra were recorded on a Bruker AM-250 or Bruker AM- 300 spectrometer and are reported in parts per million on the S scale when

CDCI3 , acetone-dg or DMSO-dg is denoted as the solvent with residual CHCI 3

(Ô 7.26), acetone (8 2.07) or DMSO (8 2.49) as an internal reference.

13C-NMR spectra were obtained on a Bruker AM-250 or Bruker AM-

78 79

300 spectrometer and are reported in parts per million on the Ô scale when

CDCI3 , acetone-dg or DMSO-dg is denoted as the solvent with residual CHCI 3

(Ô 77.0), acetone (Ô 205.7) or DMSO (S 39.7) as an internal reference.

p-Toluenesulfonylhydrazide (73).

p-Toluenesulfonyl chloride chloride (200 g, 1.05 mmol) in tetrahydrofuran

(400 mL) w as cooled to 10 °C in an ice bath with vigorous stirring. To this solution was added a mixture of 97% hydrazine (100 g) and water (100 mL) at a rate to maintain the temperature near 10^0. After addition of the aqueous

hydrazine was complete, the mixture was stirred for 30 min at room tem perature and separated. The upper tetrahydrofuran layer was washed twice with brine

(60 mL), dried over anhydrous magnesium sulfate and filtered. Addition of an

equal volume of petroleum ether (bp 35-60°C) to the mixture resuited in formation of a white solid. The mixture was cooled in an ice bath and then filtered. The filter cake was washed several times with petroleum ether and then air dried to give 172 g (90%) of 73: mp 102-104°C. (lit 101-104°C).67

Benzaldehyde tosylhydrazone (74).

Benzaldehyde (75.0 g, 71 mmol) was added with swirling to

asuspension of p-toluenesulfonylhydrazide (146 g, 0.78 mmol) inabsolute

methanol (250 mL). Dissolution of the p-toluenesulfonyl hydrazide resulted in a 80

mild exothermic reaction. Within a few minutes, benzaldehyde tosylhydrazone

(74) began to crystallize. After the mixture had been cooled in an ice bath for

1 h, the product was filtered, washed with cold methanol, and dried under vaccum to give 1 7 4 g (89%) of 74: mp 1 2 4 - 1 2 5 ^ 0 (lit 124-125°C).68

Sodium Salt of Benzaldehyde Tosylhydrazone (75).

A solution (365 mL, 1.0 M) of sodium methoxide in methanol was added

to benzaldehyde tosylhydrazone (100 g, 0.365 mol). The mixture was swirled

until dissolution was complete. The solvent was removed in vacuo to give a

solid which was dried on the house vacuum overnight. The dried sodium salt

of benzaldehyde tosylhydrazone (75) was used as obtained without further purification.69

Phenyidiazomethane (76).

The sodium salt of benzaldehyde tosylhydrazone (15 g, 51 mmol) was

added to a 100 mL RB flask equipped with a short path condenser (no water)

and a 50 mL receiver flask cooled with dry ice/acetone. The salt was heated to

IBQOC under reduced pressure (0.1 mm). After 1 h distillation of crude

phenyidiazomethane (red liquid) was complete. The crude

phenyidiazomethane was redistilled at room temperature under reduced 81

p ressure (0.1 mm) using a short path condenser (water cooled) to give 5.1 g

(85%) of 76 as a red liq u id .^ O Caution: in order to avoid explosion, phenyidiazomethane (76) should not be heated above 40°C during distillation.

Tetramethyltin (77).

Magnesium (150 g, 6.2 mol) was added n-butyl ether (1 L) under argon, in a 3 L flask equipped with mechanical stirred, addition funnel and reflux condenser. Methyl iodide (299 mL, 4.8 mmol) in n-butyl ether (300 mL) was added at a rate to cause gentle reflux. After addition was complete the mixture was stirred and cooled to room temperature overnight. Anhydrous tin (IV) chloride (90 mL, 0.77 mol) was added dropwise to the Grignard reagent. After addition of the tin (IV) chloride was complete the mixture was heated (70°C) overnight. Distillation gave a mixture of tetramethyltin and n-butyl ether

(fraction: bp 85-110°C) which on fractional distillation yielded 123 g (89%) of

77: bp 7000 (lit 750C).71

Trimethyltin Chloride (78).

Dropwise addition of tetramethyltin (78 g, 0.44 mol) into tin(IV) chloride

(17lmL, 0.15 mol) under argon resulted in moderate evolution of heat. After 82

addition was complete the mixture was heated to 45°C overnight. The product was distilled pot to pot under argon using a short stem condenser (no water) to yield 7 8 (108 g, 93%): bp 156°C (lit 156 ° C ) . 7 2

Diethylaminotrimethylstannane ( 7 9 ) .

n-Butyllithium (65.2 mL, 2.5 M in hexane) was added under argon to diethylamine (17 mL, 0.16 mol) in anhydrous diethyl ether cooled to -78°C (dry ice/acetone). After the mixture had been stirred 30 min, trimethyltin chloride

(32.5 g, 0.16 mol) in anhydrous diethyl ether (80 mL) was added dropwise. The mixture turned white after about 25 mL of the trimethyltin chloride solution had been added. After completion of the addition the mixture was warmed to room temperature, stirred 2 h, refluxed overnight and filtered in a dry box. Upon removal of the solvent under house vacuum, the mixture was distilled under reduced pressure to give 31 g (83%) of 79, a highly moisture sensitive product bp 43°C/8 mm (lit 43 °C /8 mm).T3

Phenyi(trimethyistannyi)diazomethane (70).

Phenyidiazomethane (76) (4.0 g, 33.9 mmol) cooled to -78°C (dry ice/acetone) under argon was dissolved in petroleum ether (75 mL). The red solution was added to a 3-neck flask equipped with a reflux condenser. Diethyl- 83

aminotrimethylstannane (8.1g g, 34 mmol) was then added to the solution In one portion. The reaction mixture was refluxed for 20 h or until the diazo band for phenyidiazomethane (2060 cm""I) was completely absent and only the new diazo band (2020 cm"1 ) was present. The petroleum ether solvent was then removed. The dark red residue was distilled under reduced pressure: bp

100°C, 0.45 mm to give 7.6 g (80%) of 70 as a bright red liquid (air sensitive);

IR (neat) 3105, 3080, 3060, 3010, 2920, 2460, 2320, 2200, 2020 (CN 2 ), 1845,

1780, 1710, 1650, 1600, 1500, 1480, 1445, 1345, 1300, 1190, 1165, 1085,

1040, 1000, 910, 895, 860, 780, and 750 cm-1; 1 H-NMR (250 MHz, CDCI 3 ) 6

7.40-7.04 (m, 5H, Ar), 0.57 (s, 9H, CH 3 ); 13C-NMR (63 MHz, CDCI3 ) S 135.56,

128.78, 122.89, 122.70, 38.43, -8.48; Calcd for CioHM NgSn (M+) m/e

282.0179, found GC/MS (nominal) 282.03.

N,3>Diphenyl-2>pyrazGllne-4,5-dlcarboxlmide (83).

N-Phenylmaleimide (l.lg, 6.9 mmol) in anhydrous diethyl ether (60

mL) was added to 70 (1.9 g, 6 .8 mmol) in anhydrous diethyl ether (25 ml) at -

15°C under argon. The mixture was warmed to room temperature overnight.

The solvent was removed in vacuo and the remaining solid was recrystailized

from petroleum ether/dichloromethane to give 1.7 g ( 8 6 %) of 83: mp 195-

1960C; IR (KBr) 3220, 3060, 2940, 1700, 1595, 1580, 1495, 1445, 1385, 1325, 1185,1055, 910, 780, 740, 690 cm*1 ; 1 H-NMR (250 MHz, DMSO-Dg) 5 8.38 (d,

J = 4.2 Hz, 1H, NH), 7.91-7.21 (m, 10H, Ar), 5.07-4.95 (m, 2H, CH); I^C-NMR 84

63 MHz. DMSO-dg) 5 174.79, 172.78, 144.60, 132.02, 131.27, 128.95, 128.57,

128.50,128.29, 126.90,126.51, 64.04, 53.32; Calcd for G 1 7 H13N3 O2 (M+) m/e

291.1008, found m/e 291.0997; Anal. Calcd for C 1 7 H 1 3 N3 O 2 : C, 70.09; H,

4.50. Found: C, 69.86; H, 4.78.

3-Pyrazoline-5-carbonitrlle (87).

Acrylonitrile (0.27 g, 5.1 mmol) in dry diethyl ether (40 mL) was added dropwise to 70 (1.4 g, 5.0 mmol) in dry diethyl ether (35 mL) cooled to -15°C

(ethylene glycol/dry ice) under argon. The cooling bath was removed after the addition was complete and the mixture was warmed to room temperature.

After the solvent had been removed in vacuo , the residue was recrystallized from petroleum ether/dichloromethane to yield 0.55 g (64%) of 87: mp 107-

IO8 OC; IR (KBr) 3300, 3050, 3020, 2250, 1590, 1450, 1355, 1280, 1170, 1055,

995, 890, 865, 795, 760, 685 cm-1; 1 H-NMR (250 MHz, CDCI 3 ) Ô 7.94 (d,

1H, J = 2.2 Hz, NH), 7.68-7.62 (m, 2H, Ar), 7.44-7.26 (m, 3H, Ar), 4.66-4.60 (dd,

1H. J = 9.2 Hz, CH), 3.43 (s, 1H, CH), 3.40 (d, 1H ,J = 2.0 Hz, CH); I^C-NMR (63

MHz, CDCI3 ) 5 151.68, 131.04, 129.82, 128.72, 126.28, 119.13, 48.37, 37.97;

Calcd for C 1 0 H9 N3 (M+) m/e 171.0796, found m/e 171.0801; Anal. Calcd. for

C1 0 H9 N3 : C, 70.16, H, 5.30. Found: C, 70.30; H, 5.36. 85

3-Phenyl-1-(tr!methylstannyl)-1H*benz[f]indazole-4,9-dione (93).

1,4-Napthoquinone (0.62 g, 3.9 mmol) in dry tetrahydofuran (30 mL) was

added dropwise to 70 (1.1 g, 3.9 mmol) in dry tetrahydrofuran (35 ml) cooled to

-15°C under argon. The mixture was warmed to room temperature overnight.

The solvent was removed in vacuo and the resulting solid was recrystallized

from petroleum ether/dichloromethane to give 0.79 g (92%) of 93 as a yellow

solid: mp 197-198°C: iR (KBr) 3060, 2980, 2910, 1670, 1650, 1500, 1470,

1435, 1345, 1320, 1280, 1260, 1230, 1180, 1170, 1140, 1070, 1045, 1020, 930,

780, 715, 700, 660 cm’l ; 1 H-NMR (63 MHz,acetone-d 6) 5 8.42-8.39 (d, J = 7.0

Hz, 2H, Ar), 8.27-8.21 (m, 2H, Ar), 7.92-7.81 (m, 2H, Ar), 7.51-7.40 (m, 3H, Ar),

0.79 (s, 9H, CH 3 ); 13C-NMR (250 MHz, acetone-dg) 5 180.09 (s), 178.56 (s),

153.17 (s), 153.01 (s), 136.61 (s). 135.09 (d), 134.06 (s), 133.89 (d), 133.32 (s),

129.60 (d), 129.43 (d), 128.81 (d), 128.00 (d), 126.26 (d), 119.37 (s), -1.58 (q);

Calcd for C 2 0 H 1 8 ^ 2 0 2 8 0 (M+) m/e 438.0390, found m/e 438.0396; Anal.

Calcd. for C 2o H i8 N2 Û2Sn: C, 54.96; H, 4.15. Found: C, 54.83; H, 4.15.

Dimethyl 3-Phenyl-1-trlmethyIstannylpyrazoie-4,5-dicarboxylate (101).

A solution of 70 (0.90 g, 3.2 mmol) in anhydrous diethyl ether (30 mL)

under argon was cooled to -15°C (ethylene glycol/dry ice). To this mixture was

added dimethyl acetyienedicarboxylate (0.46 g, 3.2 mmol) in anhydrous ether 86

(40 mL) dropwise. The cooler was removed Immediately after addition was complete and the mixture was warmed to room temperature. The solvent was rem oved in vacuo and the resulting solid was dissolved in dichloromethane: petroleum ether (1:2). The mixture was concentrated until most of the dichloromethane was evaporated and then placed in a refrigerator ( 0 ^ 0 ) overnight. The white crystals that deposited were collected on a sintered glass funnel to give 1.2 g (87%) of 101: mp 102-103OC; IR (KBr) 3067, 3032, 2990,

2950, 2915, 1699, 1697, 1534, 1455, 1438, 1396, 1313, 1300, 1271, 1237, 1195, 1136, 1074, 1009, 835, 695 cm'1 ; 1H-NMR (250 MHz, DMSO-dg) 5 7.56-

7.32 (m, 5H, Ar), 3.79 (s. 3H, CH 3 ), 3.69 (s, 3H, CH 3 ), 0.49 (s, 9H, CH 3); 13C-

NMR (63 MHz. DMSO-dg) 6 165.60, 161.96, 155.73, 149.28, 140.68, 132.66;

Calcd for C-| 6 H2oN2 0 4 Sn (M+) m/e 424.0445, found m/e 409.0124 (M+ - me);

FAB MS (triethyl citrate) m/e (M+ + H) 425.07; Anal. Calcd for CigHgoNgOSn:

0, 45.53, H, 4.77. Found: 0, 45.20; H, 4.77.

3,4,5-Triphenylpyrazole (105).

To a glass bomb (1x12 cm) containing petroleum ether (bp 60-9000)

and diphenylacetylene (1.0 g, 5.6 mmol) was added 70 (1.1 g, 3.7 mmol). The

mixture was heated at 140OC for 4 days. After cooling to room temperature,

0.62 g (56%) of 105 was obtained as a white solid. The product (105)

was recrystallized from petroleum ether/dichloromethane: mp 269-270OC; IR 87

(KBr) 3200. 3055, 1600, 1590, 1535, 1295, 1255, 1185, 1150, 1070, 1030, 975, 920, 770, 695 cm 'l ; 1H-NMR (250 MHz, acetone-dg) 5 12.5 (s, 1H, NH), 7.44-

7.18 (m, 15H, Ar); 13C-NMR (63 MHz, acetone-dg) Ô 135.22, 131.65, 129.40,

129.09, 128.09, 127.80, 118.03; Calcd for CaiH-jgNa (M+) m/e 296.1313, found m/e 296.1309; Anal. Calcd for C 2 iH -|gN 2 : C, 85.11, H, 5.44. Found: C,

85.29; H, 5.44.

Attempted Cycloaddition of 70 and 106.

A mixture of 70 (1.1 g, 3.7 mmol), 3-hexeyne 106 ( 0,34g, 4.2 mmol) and

petroleum ether (60 mL, bp 60-90°C) in a glass bomb (1x12 cm) was heated

at 150°C for 4 days and then cooled to room temperature. Product analysis

revealed no evidence for formation of 107.

Attempted Cycioaddition of 70 and 108.

Bis(trimethylsilyl)acetylene 108 (0.46g, 4.7 mmol), 70 (1.1 g, 3.7 mmol)

and petroleum ether (bp 60-90°C) in a glass bomb ( 1 x 12 cm) was heated at

150°C for 4 days and then cooled to room temperature. Analysis of mixture

indicated that pyrazole 109 is not formed. 88

Attempted of 70 and 110.

To a glass bomb (1x12 cm) containing petroleum ether (bp60-90°C) and bis(trimethylstannyl)acetylene 110 (1.4 g, 4.0 mmol) was added 70 (1.1 g,

3.7 mmol). The mixture was heated at 150°C for 4 days and then cooled to room temperature. There was no evidence for formation of 111.

a,a,a-Tribromotoluene (113).

Bromine (0.80 g, 4.4 mmol) in anhydrous dichloromethane (20 mL) was added to phenyl(trimethylstannyl)diazomethane (70) (0.43 g, 1.5 mmol) in anhydrous dichloromethane (40 mL) at 0°C under argon. The mixture was stirred at 0°C for 1 h, then warmed to room temperature and stirred for 6 h.

Excess bromine and the solvent were removed in vacuo. Purification by flash

chromatography (fluoril, petroleum ether) gave 0.41 g (82%) of 113: mp 56-

580C (Lit. mp 5 6 -5 7 0 0 )7 4 ; |R (KBr) 3058, 2924, 1978, 1957, 1910, 1890, 1615,

1488, 1442, 1400, 1337, 1311, 1192, 1178, 1000, 838, 721, 689, 650, 599 cm"

1 ; 1H-NMR (250 MHz, acetone-dg) 6 8.06-8.02 (m, 2H, Ar), 7.50-7.42 (m, 3H,

Ar); 13C-NMR (63 MHz, acetone-dg) 5 147.96, 131.04, 128.97, 127.15, 56.36;

Calcd for CyHgBrg (M+) m/e 325.7943, found 251.8753 (M+ - Br). 89

Photolysis of 70 in Benzene to Produce Bis(trimethylstannyi)benzaiazine (118).

Benzene (180 mL) was added to a pyrex photolysis well. Argon was bubbled through the benzene for 2 h and 70 (1.0 g, 3,6 mmol) was added. A cooling apparatus was inserted and a condenser was connected to the apparatus. The mixture was photolyzed under argon for 8 h and concentrated.

After flash chromatography (silica gel, petroleum ethyl-.ethyl acetate, 19:1) the product isolated was identified as bis(trimethylstannyl)benzalazine (118, 0.57 g, 60%): mp 180-181OC; IR (KBr) 3075, 3 045, 2970, 2900, 1550, 1485,

1445, 1390, 1310, 1290, 1230, 1175, 1155, 1075, 1025, 970, 930, 910 cm 'l;

1 H-NMR (250 MHz, CDCI3 ) Ô 7.64-7.36 (m, 10H, Ar), 0.33 (s, 18H, CH 3 ); 13C-

NMR (DEPt, 63 MHz, CDCI3 ) 8 192.88 (s), 140.79 (s), 129.39 (d), 128.29 (d),

128.02 (d), -4.95 (q): Calcd for C 2 oH 2 8 N2 Sn2 (M+) m/e 536.0296, found m/e

521.0126 (M+ - CH3 ); Anal. Calcd for C 2 oH 2 sN 2 S n 2 : C, 45.00; H, 5.29.

Found: C, 44.87; H, 5.01.

Photolysis of 70 in Cyciohexene to Produce Bis(trimethyistannyl)benzaiazine (118).

Argon was bubbled through cyciohexene (180 mL) ina pyrex photolysis well for 2 h and 70 (1.0 g, 3.6 mmol) was added. Upon addition of the cooling apparatus and a condenser, the mixture was photolyzed under argon for 8 h. 90

Flash chromatography (silica gel, petroleum ethyllethyi acetate, 19:1) of the concentrate yielded bis(thmethylstannyl)benzalazine (118, 0.57 g, 60%).

Photolysis of 70 In Ethyl Vinyl Ether to Produce Bis(trimethylstannyl)benzalazlne (118).

Argon was bubbled through ethyl vinyl ether (138) (180 mL) in a pyrex

photolysis well for 2 h and 70 (1.0 g, 3.6 mmol) was added. After insertion of the cooling apparatus and the condenser, the mixture was photolyzed under

argon for 8 h and concentrated. After flash chromatography (silica gel,

petroleum ethyl:ethyl acetate, 19:1) the product isolated was identified as

bis(trimethylstannyl)benzalazine (118, 0.57 g, 60%).

Pyrolysis of 70 in Cyclooctane.

Stannane 70 (0.85 g. 3.0 mmol) in cyclooctane (50 mL) was refluxed for

4h. After removal of solvent at reduced pressure, flash chromatography of the

solid yielded 0.59 g (73 %) of bis(trimethylstannyl)benzalazine (118) and 16

mg (6 %) of diphenylacetylene. Both products were identified by comparison

with authetic sam ples. 91

Preparation of Bis(trlmethylstannyl)benzalazlne (118) by 70/Rhodlum(ll) Acetate Catalyzed Decomposition of 70.

Rhodium(ii) acetate (4 mole %) was added under argon to anhydrous dichloromethane (30 mL) in a 250 mL flask covered with aluminum foil equipped with an addition funnel. Phenyl(trimethylstannyl)diazomethane (70)

(0.40 g, 1.4 mmol) was syringed into the anhydrous dichloromethane (80 mL)

and the solution was added dropwise over 6 h to the rhodium(ll) acetate. The

reaction mixture was filtered and then concentrated to a solid. Flash

chromatography (fluorsil, petroleum ether) afforded 0.36 g (95%) of 118 a s a

yellow solid: mp 180-18100; the 1 H-NMR and mass spectra of the solid were

identical to those reported for 118 earlier.

Preparation of a-Trlethyisiiyi-a-trimethyistannyitoiuene (129).

Trieihylsilane (7.0 g, 60 mmole) and rhodium(ll) acetate (4 mole %) was

added to dry dichlorommethane (30 mL) in a 250 mL flask covered with

aluminum foil and equipped with an addition funnel. Phenyl(trimethyl-

stannyl)diazomethane (70) (0.41 g, 1.5 mmol) in dry dichloromethane (80 mL)

was added over 6 h. The mixture was filtered and then concentrated. Flash

chromatography (silica gel, petroleum ether) of the product gave 0.45 g (84%)

of 129 as a colorless oil; IR (neat) 3060, 3020, 2960, 2915, 2875, 1595, 92

1490, 1460, 1450, 1420, 1380, 1245, 1220, 1070, 1020, 970, 905, 840, 770,

700 cm-1 ; 1 H-NMR (250 MHz, CDCI3 ) S 7.23-8.98 (m, 5H, Ar), 2.01 (s, 1 H, CH),

1.00 (t, J = 7.8 Hz, 9H, CH 3 ), 0.76-0.60 (m. 6 H, CH), 0.15 (s, 9H, CH 3 ); 13 c-

NMR (DEPt. 63 MHz, CDCI3 ) S 144.76 (s), 128.14 (s), 127.93 (d), 122.70 (d),

21.33 (d), 7.74 (q), 5.12 (t), -7.99 (q); Calcd for C i 6 H 3 oSiSn (M+) m/e

370.1139, found 370.1157; Anal. Calcd for C i 6 H3 oSISn: C, 52.05; H, 8.19.

Found: C, 52.02; H, 7.99.

Preparation of a-Triisopropyl-a-trimethylstannyitoluene (131).

Rhodium(ll) acetate (4 mole %) was added to triisopropylsilane (10 g, 63

mmol) In dry dichloromethane (30 mL) contained in a flask covered with

aluminum foil. In6 h 70 (0.67 g, 2.4 mmol) in dry dichloromethane (80 mL) was

added The mixture was filtered and concentrated. Flash chromatography

(silica gel, petroleum ether) gave 0.75 g (76%) of 131 as a colorless oil; IR

(neat) 3070, 3020, 2955, 2920, 2865, 1595, 1490, 1460, 1425, 1375, 1335,

1210, 1070, 1035, 1010, 905, 840, 770, 700 cm"1;1 H-NMR (300 MHz, CDCI 3 )

Ô 7.19-6.93 (m, 5H, Ar), 1.92 (s, 1H, CH), 1.48-1.25 (m, 6 H, CH), 0.97-0.92 (t, J =

7.1 Hz, 9H, CH 3 ), 0.65-0.53 (m, 6 H, CH), 0.09 (s, 9H, CH 3 ); 13C-NMR (DEPt, 75

MHz, CDCI3 ) 5 144.80 (s), 128.13 (d), 128.05 (d), 122.60 (s), 22.08 (d), 18.69

(q), 17.64 (t), 16.96 (t), -8.00 (q); Calcd for C igH 3 6 SiSn (M+) m/e 412.1608,

found m/e 412.1653; Anal. Calcd C i 9 H3 0 SiSn: C, 55.49; H, 8.82. Found: C,

55.69; H, 8.95. 93

Preparation of a-Dlmethylphenylsllyl-a-trlmethylstannyltoluene

(1 3 3 ).

Over 6 h 70 (0.68 g, 2.4 mmol) was added dropwise to rhodium acetate (4 mole %) and dimethylphenylsilane (5 g, 37 mmol) in anhydrous dichloromethane (30 mL). The mixture was filtered and concentrated.

Purification by flash chromatography (silica gel, petroleum ether:ethyl acetate,

19:1) yielded 0.74 g (79%) of 133 as a colorless oil; IR (neat) 3060, 3020, 2960,

2900, 1595, 1490, 1450, 1430, 1250, 1210, 1115, 1070, 1035, 1000, 905, 835,

760,700 cm-1 ; 1 H-NMR (250 MHz, CDCI3 ) 5 7.54-6.95 (m, 10H, Ar), 0.46 (s,

3H, CH3 ), 0.33 (s, 3H, CH3 ), -0.01 (s, 9H, CH 3 ); ISq-NMR (DEPt, 63 MHz,

CDCI3 ) 8 144.27 (s), 139.51 (s), 133.77 (d), 128.90 (d), 128.18 (d), 128.15 (d),

127.65 (d), 122.87 (d), 24.53 (d), -1.39 (q), -1.81 (q), -8.23 (q); Calcd

C l 8 H 2 6 SiSn (M+) m/e 390.0826, found m/e 390.0838; Anal. Calcd for

C i 8 H2 6 SiSn: C, 55.55; H, 6.73. Found: C, 55.83; H, 6.58.

Preparation of a-Cyclohexyldlmethylsllyl>a-trlmethylstannyltoluene

(1 3 5 ).

To a mixture of cyclohexyldimethylsilane (5.0 g, 35 mmole) and rhodium

acetate (4 mole %) under argon in dry dichloromethane (30 mL) was added 70

(0.65 g, 2.3 mmol) in dry dichloromethane (80 mL) dropwise over 6 h. After

filtering, the reaction mixture was concentrated. Flash chromatography 94

(silica gel, petroleum) gave 0.76 g (83%) of 135 as a colorless oil; IR (neat)

3070, 3020, 2920, 2845, 1595, 1490, 1450, 1410, 1250, 1210, 1105, 1075,

1035, 1000, 905, 890, 840, 765, 700 cm-1; 1 H-NMR (250 MHz, CDCI 3 ) 8 7.20-

6.91 (m, 5H, Ar), 1.78-1.60 (m, 4H, CH; ring), 1.22-0.99 (m, 6 H, CH; ring), 0.64-

0.53 (m, 1H, CH; ring), 0.92 (s, 9H, CH 3 ), 0.06 (s, 3H, CH3 ), 0.03 (s. 3H, CH3 );

13c-NMR (DEPt, 63 MHz, CDCI3 ) S 144.90 (s), 128.12 (d), 128.06 (d),

122.61(d), 28.11 (t), 28.04 (t), 27.54 (t), 27.45 (t), 26.96 (t), 25.68 (d), 22.19 (d), - 3.23 (q), -3.69 (q), -8.04 (q); Calcd for C-igHaaSiSn (M+) m/e 396.1295, found m/e 396.1133; Anal. Calcd CigHggSiSn: C, 54.70; H, 8.16, Found: C, 54.72; H,

8.22.

Rhodlum(ll) Acetate Decomposition of 70 In the Presence of

Styrene (136A).

To styrene (8.0 g, 77 mmol) and rhodium acetate (4 mole %) in dry dichloromethane (30 mL) under argon in a flask covered with aluminum foil was added 70 (0.52 g, 1.9 mmol) in dry dichloromethane (80 mL) dropwise over 6 h.

The mixture was filtered and then concentrated under reduced pressure to a solid. Flash chromatography (florisil, petroleum ether) gave 0.38 g (75%) of

bis(trimethylstannyl)benzlazine (118). The mp and 1 H-NMR of the product

were identical with an authentic sample. No evidence was found for

cyclopropane 137 A. 95

Rhod!um(ll) Acetate Decomposition of 70 in the Presence of 2- methyi-2-butene (136B).

A solution of 70 (0.52 g, 1.9 mmol) in anhydrous dichloromethane (80 mL) was added dropwise under argon in 6 h to a mixture of 2-methyl-2-butene

(10 g, 143 mmol) and rhodium acetate (4 mole %) in anhydrous dichloromethane (30 mL) in an aluminum covered flask. Filtration and concentration of the reaction mixture in vacuo yielded a solid. Flash chromatography (florisil, petroleum ether) gave 0.39 g (77 %) of bis(trimethylstannyl)benzalazine (118) whose mp and NMR are identical with that of an authentic sample. Cyclopropane 137B was not detected.

Rhodium(li) Acetate Decomposition of 70 in the Presence of

Cyciopentene (1360).

Rhodium acetate (4 mole %) was added to dry dichloromethane (30 mL) and cyciopentene (7.0 g, 103 mmol) in an aluminum shielded flask (250 mL).

O ver 6 h 70 (0.48 g, 1.7 mmol) in dry dichloromethane (80 mL) was added dropwise. After filtration the mixture was concentrated to a solid. Flash chromatography (florisil, petroleum ether) gave 0.33 g, (72 %) of

bis(trimethylstannyl)benzalazine (118). The mp and the 1 H-NMR of 118 96

correspond to that of an authentic sample. Cyclopropane derivative 1370 was not found.

Rhodium(ll) Acetate Decomposition of 70 in the Presence of Methyienecyciopentane (136D).

A solution of 70 (0.49 g, 1.7 mmol) In anhydrous dichloromethane (80 mL) w as added under argon in 6 h to methyienecyciopentane (5.0 g, 81 mmol) and rhodium acetate (4 mole %) In anhydrous dichloromethane (30 mL). The mixture was filtered and concentrated to a solid. Flash chromatography

(florisil, petroleum ether) gave 0.38 g (83%) of bls(trimethylstannyl)benzalazlne

(118) of proper mp and H-NMR. No evidence was found for cyclopropane derivative 1370.

Rhodium(li) Acetate Decomposition of 70 in the Presence of Methyienecyciohexane (136E).

Dichloromethane (80 mL) containing 70 (0.55 g, 2.0 mmol) (80 mL) was added under argon In 6 h to methyienecyciohexane (5.0 g, 52 mmol) and rhodium acetate (4 mole %). The mixture was filtered and then concentrated under reduced pressure. Flash chromatography (florisil, petroleum ether) gave 97

0.39 g (73%) of bis(trimethylstannyl)benzalazine (118) as identified by its mp and its 1 H-NMR with authentic sample. Cyclopropane 136E was not obtained.

(E)-2-Ethoxy-1-phenyl>1-trimethylstannylcyclopropane (139).

A mixture of 70 (0.55 g, 2.0 mmol) in dry dichloromethane (80 mL) was

added to a solution of rhodium acetate (4 mole %), dry dichloromethane (30

mL) and ethyl vinyl ether (8.0 g, 111 mmoi) in 6 h. After filtering, the mixture was

concentrated in vacuo to an oil. Flash chrom atography (florisil, petroleum

ether) gave 0.51 g (80%) of 139 as a colorless oil; IR (neat) 3058, 3020, 2980,

2920, 2870, 1600, 1495, 1445, 1375, 1350, 1320, 1195, 1090, 1070, 975, 910 cm-1; 1 H-NMR (250 MHz, acetone-dg) 5 7.22-7.00 (m, 5H, Ar), 3.61-3.45 (m,

3H, CH; ring, CH), 1.08-0.92 (m, 5H, CH; ring. Me), -0.02 (s, 9H, Me); I^C-NMR (DEPt, 63 MHz, acetone-Dg) 5 144.63 (s), 130.35 (d), 128.54 (d), 124.95 (d),

66.40 (t), 60.78 (d), 22.55 (s), 16.16 (t), 15.44 (q), -10.87 (q); Calcd for

C i4 H2 2 0 Sn (M+) m/e 326.0692, found 326.0687; Anal. Calcd for C-| 4 H2 2 0 Sn:

C, 51.74; H, 6.82. Found: C, 51.70; H, 7.10.

(E)-2-Butoxy-1 -phenyl-1 -trim ethyistannylcyclopropane (141).

Stannane 70 (0.65 g, 2.3 mmol) in anhydrous dichloromethane (80 mL)

was added over 6 h under argon to a mixture of n-butyl vinyl ether ( 8.0 g, 80 98

mmol) and rhodium acetate (4 mole %) in anhydrous dichloromethane (30 mL).

After filtering, the mixture was concentrated in vacuo to an oil. Flash chromatography (florisil, petroleum ether) yielded 0.67 g (82%) of 141 as a colorless oil; IR (neat) 3060, 3020, 2960, 2940, 2870, 1600, 1495, 1450, 1440,

1350, 1310, 1190,1130,1090, 1035, 970, 880, 775, 705cm-1 ; 1 H-NMR (300 MHz, acetone-dg) 5 7.22-6.99 (m, 5H, Ar), 3.58-3.51 (m, 1H, CH), 3.48-3.39 (m,

2H, CH), 1.39-1.30 (m, 2 H, CH), 1.21-1.11 (m, 2H, CH), 1.10-1.01 (m, 2H, CH; ring), 0.76 (t, J = 7.3 Hz, 3H, CHg), -0.07 (s, 9H, CH 3 ); 13C-NMR (DEPt, 75 MHz, acetone-dg) 6 144.46 (s), 130.31 (d), 128.44 (d), 124.88 (d), 70.75 (t), 60.86 (d),

32.47 (t), 22.58 (s), 19.80 (t), 16.12 (t), 14.06 (q), -10.83 (q); Calcd for

C i 6 H2 6 0 Sn (M+) m/e 354.1005, found 354.0993; Anal. Calcd for C-igHggOSn:

C, 54.53; H, 7.42. Found: C, 54.55; H, 7.30.

(E)-2,4-dihydropyranyl-1-phenyl-1-trimethylstannylcyciopropane

(1 4 3 ).

A solution of 70 (0.6 g, 2.1 mmol) in anhydrous dichloromethane (80 mL) was added to dihydropyran (10 g, 119 mmol) and rhodium acetate (4 mole %) in anhydrous dichlormethane (30 mL) under argon. The mixture was filtered and concentrated in vacuo. Flash chromatography (florisil, petroleum ether) of the oil gave 143 (0.51 g, 71%) as a colorless oil; IR (neat) 3070, 3050, 3020,

2960, 2920, 2850, 1600, 1495, 1445, 1390,1375, 1310,1235, 1190, 1150,

1110, 1085,1065, 1035, 999,885, 820,770, 705cm'1; 1 H-NMR (300 MHz, 99

acetone-dg) 6 7.30-7.06 (m, 5H, Ar), 3.82 (d, J = 6.4, H, CH), 3.37-3.21 (m, 2H,

CH), 2.06-1.97 (m, 2H, CH). 1.42-1.38 (m, 1H, CH), 1.09-1.03 (m, 1H, CH). 0.42- 0.37 (m, 1H, CH), -0.01 (s, 9H, CHg); 13c-NMR (75 MHz, acetone-dg) 5

142.60 (s), 130.73 (d), 128.69 (d), 124.57 (d), 64.58 (t), 57.15 (d), 23.49 (s), 23.06 (t), 19.24 (t), 17.96 (d), -11.11 (q); Calcd for C ig H a a O S n (M+) m/e

338.0693, found 338.0720; Anal. Calcd for CigH 2 2 0 Sn: C, 53.46; H, 6.58.

Found: C, 53.63; H, 6.57.

Rhodium Acetate Decomposition of 70 in the Presence of Vinyl

Acetate (144).

Stannane 70 (0.47 g, 1.7 mmol) in dry dichloromethane (80 mL) was added under argon in 6 h to vinyl acetate (7.0 g, 71 mmol) and rhodium acetate

(4 mole %) in dry dichloromethane (30 mL). The mixture was filtered and then concentrated under reduced pressure to a solid. Flash chromatography (florisil, petroleum ether) gave 0.33 g (73%) of bis(trimethylstannyl)benzalazine (118) whose mp and 1 H-NMR are identical with that of an authentic sample.

Cyclopropane 145 was not found. 100

2,2-DImethoxy-1~trimethylstannyl-1-phenylcyclopropane (147).

To a mixture of 1,1-dimethoxyethene (8.0 g, 100 mmol) and rhodium

acetate (4 mole %) in anhydrous dichloromethane (30 mL) under argon was

added 70 (0.60 g, 2.1 mmol) in anhydrous dichloromethane (80 mL) dropwise

over 6 h. Filtration and concentration of the mixture yielded an oil. Flash

chromatography (florisil, petroleum ether:ethyl acetate, 19:1) gave 0.67 g (92%)

of 147 as a colorless oil; IR (neat) 3060, 3020, 2940, 2930, 1595, 1490, 1445,

1335, 1240, 1220, 1150, 1055, 1035, 1025, 880, 765, 700 cm’l; 1 H-NMR (250

MHz, acetone-dg) Ô 7.26-7.04 (m, 5H, Ar), 3.39 (s, 3H, CH 3 ), 3.23 (s, 3H, CH3),

1.39 (d, J = 5.1 Hz,1H, CH). 1.32 (d, J = 5.1 Hz, 1H. CH), 0.04 (s, 9H, CH 3 ); 13c-

NMR (DEPt, 75 MHz, acetone-dg) d 143.50 (s), 129.59 (d), 128.63 (d), 125.33

(d), 95.52 (s), 53.29 (q), 53.08 (q), 33.10 (s), 21.41 (t), -9.12 (q); Calcd for

C i 4 H 2 2 0 2 Sn (M+) m/e 342.0642, found 342.0609; Anal. Calcd for

C i 4H 2 2 0 2 Sn: C, 49.31 ; H, 6.50. Found; C, 49.11 ; H, 6.32.

Determination of Relative Reactivities of 128 and 138 towards 70 /

Rhodium(ll) Acetate.

Rhodium(ll) acetate (4 mole %) was added to triethylsilane (128) (8 g, 69

mmoi) and ethyl vinyl ether (138) (5 g, 69 mmol) in dry dichloromethane (40mL)

in a flask covered with aluminum foil. Stannane 70 (0.7 g, 2.5 mmol) in dry

dichloromethane (80 mL) was added in 6 h.. The mixture was filtered and 101

concentrated. Flash chromatography (silica gel, petroleum ether) gave 0.55 g

(60 %) of 129 and0.19 g (24 %) of 139. Both 129 and 139 were identified by comparison with authetic samples.

Phenyl(trlphenylsilyl)diazomethane (159).

n-Butyllithium (1.7 mL, 1.6 M in hexane) was added dropwise to 70 (0.77 g, 2.7 mmol) in dry tetrahydrofuran (30 ml) at -78°C under argon. Triphenylsilyl chloride (0.81 g, 2.7 mmol) in dry tetrahydrofuran (45 mL) was added dropwise.The mixture was stirred overnight and warmed to room temperature.

The solvent was removed in vacuo and the remaining yellow solid was

dissolved in dichloromethane, filtered and petroleum ether (10 mL) was added.

The mixture was concentrated until most of the dichloromethane was

evaporated and then placed in a refrigerator (0°C) overnight. The yellow

crystals that deposited were filtered to give 159 (0.49 g, 48%): mp 149-151 °C

(Lit. mp 150-15100)75; |R (KBr) 3030, 2045, 1585, 1490, 1435, 1285, 1170, 1110,1040,1010, 940, 840, 755, 700 cm-1; Ir-NMR (250 MHz, acetone-dg) 5

7.69-7.41 (m, 15H, Ar), 7.19-6.96 (m, 5H, Ar); Calcd for CasHaoNaSi (M+) m/e

376.1395, found m/e 376.1347. 102

Phenyl(trIphenylgermyl)diazonnethane (160).

Stannane 70 (0 .8 g, 2.8 mmol) was added under argon to dry tetrahydrofuran (30 mL) cooled to -780C under argon. n-Butyiiithlum (1.9 mL,

1.6 M in hexane) was added slowly and the mixture was stirred for 30 min.

Triphenylgermyl chloride (1.0 g, 2.9 mmol) in dry tetrahydrofuran (45 mL) was then added dropwise. After the mixture had been stirred overnight and warmed to room temperature, the solvent was removed in vacuo and the remaining

yellow solid was redissolved in dichloromethane, filtered and recrystallized from

petroleum ether/dichloromethane to give 0.80 g (67%) of 160; mp 153-154°C

(Lit. mp 1 5 3 -1 5 4 0 0 )7 6 : |R (KBr) 3040, 2040, 1585, 1490, 1435, 1300, 1170, 1095,1035, 1005 cm’l; 1H-NMR (250 MHz, acetone-dg) 5 7.66-7.41 (m, 15H,

Ar), 7.21-6.94 (m, 5H, Ar); Calcd for C 2 5 H2 oG eN 2 (M+) m/e 422.0836, found

m/e 422.0871.

Phenyl(trlphenylstannyl)dlazomethane (161 ).

n-Butyllithium (1.0 mL, 1.6 M in hexane) w as added dropwise to 70 (0.42

g, 1.5 mmol) in dry tetrahydrofuran (30 mL) at -7800 under argon. The solution

was stirred for 30 min and triphenyitin chloride (0.64 g, 1.6 mmol) in dry

tetrahydrofuran (45 mL) was added slowly. The mixture was stirred overnight

and warmed to room temperature. The solvent was removed in vacuo and the

remaining orange solid was dissolved in dichloromethane and filtered. 103

Crystallization of the product from petroleum ether/dichloromethane yielded

0.32 g (45%) of 161: mp 150-151OQ; IR (KBr) 3040, 3020, 2020, 1595, 1445, 1435, 1300, 1160, 1070,1005, 990, 690 cm'1 ; 1 H-NMR (250 MHz, acetone-dg)

7.75-7.45 (m, 15H, Ar), 7.22-6.93 (m, 5H, Ar); Calcd for C 2 sH 2 oN2 Sn (M+) m/e

468.0648, found 468.0610; Anal. Calcd for CasHaoNaSn: C, 64.28; H, 4.32.

Found: C, 64.33; H, 4.41.

Phenyl(triphenylplutnbyl)diazomethane (162).

n-Butyllithium (1.3 mL, 1.6 M in hexane) was added slowly to a solution

of 70 (0.55 g, 2.0 mmol) in dry tetrahydrofuran (30 mL) at -78°C (dry

ice/acetone) under argon. After 30 min, triphenyllead chloride (1.0 g, 2.0 mmol)

in dry tetrahydrofuran (45 mL) was added dropwise. The mixture was warmed

to room temperature overnight. The solvent was removed in vacuo and the

remaining red solid was redissolved in dichloromethane and filtered. The

product was recrystallized from petroleum ether/dichloromethane to give 0.47 g

(42%) of 162: mp 124-125°C; IR (KBr) 3045, 3015, 2005, 1595, 1575, 1470, 1310,1155, 1005, 890, 740, 690 cm'1; 1 H-NMR (250 MHz, acetone-dg) Ô 7.90-

6 .8 8 (m, 15H, Ar), 7.65-7.33 (m, 5H, Ar); Calcd for C 2 sH 2 oN 2 Pb (M+) m/e

556.1392, found 556.1306; Anal. Calcd for C 2 5 H2 oN 2 Pb: C, 54.04; H, 3.63.

Found; C, 54.05; H, 3.79. 104

DiphenylphosphinyI(phenyl)dlazomethane (163).

n-Butyllithium (1.1 mL, 1.6 M in hexane) was added slowly to 70 (0.45 g,

1.8 mmol) under argon In anhydrous tetrahydrofuran (30 mL) cooled to -78°C

(dry ice/acetone). After the mixture had been stirred for 30 min, diphenylphosphinic chloride (0.39 g, 1 .6 mmol) in dry tetrahydrofuran (45 mL) was added dropwise. The solution was stirred and warmed to room temperature overnight. The solvent was removed and the orange solid residue was redissolved in dichloromethane and filtered. Crystallization of the product

from petroleum ether/dichloromethane gave 163 (0.38 g, 65%): mp 156-15700

(Lit. mp 155-15000)77; |r (KBr) 3050, 2075, 1598, 1490, 1445, 1405, 1300, 1188,1125,1030,1000, 960 cm’l; 1 H-NMR (250 MHz, acetone-dg) 5 8.04-7.37

(m, 10H, Ar), 7.34-7.10 (m, 5H, Ar); Oalcd fo rO ig H isN aO P (M+) m/e 318.0922,

found m/e 318.0983.

Preparation of 3,6-Dlphenyi-1,2,4,5-tetrazlne (164).

n-Butyllithium (1.4 mL, 1.6 M in hexane) was added slowly to a solution

of 70 (0.58 g, 2.0 mmol) in dry tetrahydrofuran (30 mL) cooled to -78°0 under

argon. After the mixture had been stirred for 30 min, phenylmercuric chloride

(0.70 g, 2.2 mmol) in dry tetrahydrofuran (45 mL) was added dropwise. The

solution was warmed to room temperature overnight. After filtration, the 105

solvent was removed in vacuo. Purification of the residue by flash chromatography (silica gel, petroleum ether:ethyl acetate, 9:1) gave 164 (0.16 g, 6 8 %): mp 194-19600 (Lit. mp 1 9 5 0 0 )7 8 ; | r (KBr) 3100, 3040, 1595, 1385,

1100, 1070, 1050, 1020, 910, 760, 680, 580 cm 'l; 1 H-NMR (250 MHz, acetone- de) 5 8.65-8.61 (m, 4H, Ar). 7.72-7.66 (m, 6 H, Ar); 13c-NMR (DEPt, 63 MHz, acetone-dg) 8 164.75 (s), 148.02 (s), 133.39 (d), 130.22 (d), 128.62 (d); Oalcd for C 1 4 H1 0 N4 (M+) m/e 234.0905, found m/e 234.0888.

p-Chlorobenzoylbenzalazine (173).

n-Butyllithium (1.1 mL, 1.6 M in hexane) was added slowly to a solution

of 70 (0.43 g, 1.5 mmol) in anhydrous tetrahydrofuran (30 mL) cooled to -78°0

under argon. The mixture was stirred for 0.5 h. p-Chlorobenzoyl chloride (0.30

g, 1.7 mmol) in anhydrous tetrahydrofuran (45 mL) was added dropwise. The

mixture was warmed overnight to room temperature. The solvent was removed

in vacuo and the resulting solid was extracted using dichloromethane and

brine. The extract was dried over anhydrous Na 2 S 0 4 and concentrated in

vacuo. The product was recrystallized from petroleum ether/dichloromethane to

give 173 (0.11 g, 42%): mp 172-17300; IR (KBr) 3040, 2760, 1570, 1520, 1480,

1400, 1330, 1150, 1090, 1015, 940, 820,770, 680, 630 cm'l ; 1 H-NMR (250

MHz, DMSO-dg) 6 7.93 (dd, 7.7 Hz, 4H, Ar), 7.87 (s, 1 H, CH), 7.48-7.34 (m, 10 H, 106

Ar): 13C-NMR (63 MHz, DMSO-dg) 8 174.81, 135.10, 135.09, 132.57, 131.41,

129.32,128.71,128.21, 127.72, 125.59, 91.96; Calcd for C 2 1 H1 5 CIN2O (M+) m/e 346.0873, found 346.0918; Anal. Calcd for C 2 1 H 1 5 CIN2 O: C, 72.73; H,

4.36; N, 8.08. Found: C, 72.15; H, 4.31 ; N, 7.76.

p-Trlfluoromethylbenzoylbenzalazine (174).

A solution of 70 (0.42 g, 1.5 mmol) and dry tetrahydrofuran (30 mL) was cooled to -78°C (dry ice/acetone) under argon. n-Butyllithlumi (1.0 mL, 1.6 M in hexane) was added dropwise with stirring. After 30 min, p-trifluoromethylbenzoyl chloride (0.34 g, 1.6 mmol) in dry tetrahydrofuran (45 mL) was added slowly and the reaction mixture was allowed to warm to room temperature overnight. The solvent was removed in vacuo and the resulting solid was extracted using dichloromethane and brine. The extract was dried over anhydrous Na 2 S 0 4 and concentrated in vacuo. Recrystallization of the product from petroleum ether/dichloromethane gave 0.12 g (43%) of 174: mp 191-

192°C; IR (KBr) 3080, 2800, 1635, 1605, 1585, 1535, 1498, 1430, 1325, 1165,

1115,1075, 1025, 955, 890, 840, 775, 690, and 640 cm 'l ; 1 H-NMR (250

MHz, DMSO-de) 6 8.00 (s, 1 H, CH), 7.93 (dd, 6,4 Hz, 4H, Ar), 7.71 (d, 8.3 Hz,

2H, Ar), 7.58 (d, 8.3 Hz, 2H, Ar), 7.45-7.37 (m, 6 H, Ar); 13C-NMR (63 MHz, DMSO-de) 5 174.79 (s), 140.83 (s), 131.54 (d), 128.79 (d), 128.09 (s), 127.7 (d),

126.33 (s), 126.28 (d), 124.62 (d), 92.16 (s); Calcd for C 2 2 H1 5 F3 N2 O (M+) m/e

380.1136, found 380.1184; Anal. Calcd for C 2 2 H1 5 F3 N2 O: C, 69.47; H, 3.97;

N, 7.36. Found: C, 69.53; H, 4.21 ; N, 7.18. APPENDIX A

1 H-NMR and I^C-NMR Spectra for New Compounds

107 CgHs— c —Sn(CH3)a 70

3.5 2.s PPM

Figure 9. 250 MHz ^ H-NMR of Phenyl(tr!methylstannyl)d!a 2omethane (70).

g 11^ CgHs— C—Sn(CH 3)3 7 0

~ T ~ "T- 1" '"T" "I ...... I ' - ’T” 130 ISO 110 100 90 80 70 60 ‘to 30 20 10 -10 PPM

Figure 10. 63 MHz I^C-NMR of Phenyl{trimelhyistannyl)diazomethane (70). N—CrH,

0.5 PPM

Figure 11. 250 MHz ^ H-NMR of N,3-Diphenyl-2'pyra20ilne-4,5-dicarboxlmicie (83). 83

nr T' T" J70 160 150 140 no 100 GO 40 PPM

Figure 12. 63 MHz of N,3-Dipheny!-2-pyrazollne-4,5-dlcarboxlmlde (83). /

y u Vu

1----,---- 1---- r- 1—'—I—«—r 1------'------1------'-1------'-1------'------1------'------1------'-1------'-1------1-1------'-1------'-1------'-1------'-1------1-1------1-1------r 8.0 7.8 7 .6 7.4 7.2 7.0 6.8 6.6 6.4 6.2 6.0 5.6 ^5^6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3 .6 3.4 3.2

Figure 13. 250 MHz "'h -NMR of 3-Pyrazo!ine-5-carbon!trl!e (87).

NJ ,CN

"I"'" 150 130 80 70 NO 120 110 lo" so 40

Figure 14. 63 MHz ‘•^c-NMR of 3-Pyrazo!ine-5-carbonitii!e (87).

OJ 93

2.5 PPM

Flqure 15. 250 MHz ^H-NMR of 3-Phenyl-1-{lrimethylstannyl)-1H-ben2lf]inda2oIe-4.9-dione (93). 93

■'T*' ”T” ”T” T ”T" "T -T ~ r Tr 180 170 Teo 150 130 120 100 ”1 ^ 80 60 50 40 30 20 PPM io 0

F/gure 16. 63 MHz 13C-NMR of 3-Phenyl-1-(trimelhylstannyl)-1H-benzIflinda2ol0-4,9

[kl

3.5 PPM

Figure 17. 250 MHz "'h -NMR of 3-Phenyl-1-trimethylstannylpyra20le-4,5-d!carboxylate (101).

»—4 0\ "-T" ■T^ 160 150 140 s 100 PPM

Figure 18. 63 MHz ‘•^C-NMR of 3-Phenyl-1-trimelhylstanny!pyrazo!0-4,5-clicarboxy!atô (101). H \ yCgHe

CgHg 105

j 1 U

I I I I T I I 1 I 1 I r T | f - T T i I I I I r ’ l I I r I " y - ] T T I ■! ] I I I I I I I I I I 1 r r-T T r I I I I I M I I I I 1' I I I' T r I ' l 1 I -1- 1-7 1 1 11 | 1 1 1 1 j 1 1 1 1 | 1 1 1 1 | 1 1 ; , , , , , , , , , , 13.5 13.0 12.5 12.0 11.5 11.0 10.5 Ip.O 9.3 9.0 8.8 8.0 7.8 7.0 6.8 6.0 8.8 5.0 4.8 4.0 3.8. 3.0 2.5 I ' ' PPM

Figure 19. 250 MHz ^H-NMR of 3,4,5-Triphenylpyrazole (105). 00 ■OqH s

CqHq 105

TiiTvn*-r''V(i-*rm‘îTffr‘ri‘*'ifîriii‘'f‘fViVfH‘‘i*‘ff*|Tri^^*#lww irni'fftiVTii‘iîVriV>ifif^ ^<)(ifim,),^j^ SfN

...... I ...... ),,,.|.,,.| .iii|rr.t^TT " I" " " '"I...... r r y r r ’•V ' ' "T I . I" 160 150 140 130 ISO 110 100 90 80 70 GO 50 40 30 PPM

Figure 20. 63 MHz 3,4,5-Triphenylpyrazole (105).

vO 11 8

jJ lL

3.5 PPM

Figure 21. 250 MHz 1H-NMR of Bls(trlm 0thylslannyl)ben 2alazlne (118). — i I I ...... I ...... I'...... I...... I"-'...... I ...... |..,,|,.^,|.,.,|,'M|ii 190 190 170 160 ISO 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 PPM

Figure 22. 63 MHz t^C-NMR of Bis{trimethylstannyl)benzalazine (118). S1(CH2CH3)3 CgHg— Ç—8n(CH3)3 H 1 2 9

l i k

v I 1 - T - T I I I T I I "I-I I 1-1-1 1—I—1—I I "I—I—I—I- ■ I I 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 0.0 PPM

Figure 23. 250 MHz ^H-NMR of a-Trlethyisiiyi-a-trimethylstannylloiuene (129). ~r~ 'T' T - r y , - 140 Taô^ Tio^ Too go 70 PPM

Figure 24. 250 MHz “'^C-NMR of a-Tr!ethy!sllyl*a-tr!methyistannylto!uene (129). SKCHaCHaCHg)» CgHg— Ç—Sn(CH3)3

131

5.5 3.5 0.0 PPM

Figure 25. 300 MHz '•h -NMR of a-Triisopropyisiiyl-a-trimethylstannyitoluene (131). SKCH2 CH2 CH3 ): CgHg— 0 —Sn(CH3)3

H 131

140 130 120 110 100 90 80 70 ' ' lo" 50 40 IT 20 10 -10 PPM

Figure 26. 75 MHz I^C-NMR of a-Trilsopropyls!iyl-a-trimethylstannylto!uene ( 131).

5 SKCH^hCeHs CgHg— Ç—Sn(CH3)3 H 1 3 3

-T I I'- r -i- •» *•»* »'rI I I I I ' ' I I ' - ’• I - ' ' ' I I I I I I ' ' ' I-r 7.5 7.0 6 .5 6 .0 5 .5 5 .0 4.5 4 .0 3 ,5 3.0 2.S iO t'S 1.0 .S' O.o PPM

Figure 27. 250 MHz ^H-NMR of cx-Dimeihyiphenyisllyl-a-trimethylstannyltoluene (133).

6^ Si(CH3)2C6H5 CgHs— Ç—Sn(CH3)3

1 3 3

~i— ”T” • ~ T ” " " " ' I ...... I ■ 140 130 120 110 100 90 80 70 60 50 "To" ~3^ 20 PPM 10 0

Figure 28. 63 M Hz13q.nmr of a-Dimethyiphenyisiiyl-a-trimethylstannyltoluene (133). 5 .0 4 .0 3 .5 3 .0 2 .5 PPM

Figure 29. 250 MHz ^H-NMR o( a-Cyclohexyidlmethylsilyl-a-trimethylstannyiloluene (135). % SI(CH3)2C6Hi, CsHs— C—8n(CHa)3 H 135

■■ . , iin n u I,It,1 wII%,i||ifir^riririi^^iT ,^ '"n h fn

'■ ' I I 11 I M ' I ' I I ...... I "•'...... ' I " "’ I " '-' "T" ...... |- -"T^ T" 140 130 120 110 100 90 70 60 so 40 30 20 10 PPM

Figure 30. 63 MHz i^C-NMR of a-CyclohexyldimethylsiIyi-a-trimelhy!stanny!toluene (135). PPM

Figure 31. 250 MHz ^ H-NMR of (E)-2-Etfioxy-l-phenyl-1-trimethylstannylcyclopropan0 (139). oOJ I...... I" . ''I...... I'" 150 MO 130 120 110 100 90 80 70 60 50 40 30 20 10 0 -1 0 PPM

Figure 32. 63 MHz I^C-NMR of {E)-2-Ethoxy-1-phenyi-1-trimethy!stannylcyclopropane (139).

OJ u;

PPM

Figure 33. 300 MHz 1 H-NMR of (E)-2-Butoxy-1-phenyl-1-trimethyistannyicyc!opropane (141). '-r T' T —t—"' no 100 00 no 50 10 0 -10

Figure 34. 75 MHz '’^C-NMR of (E)- 2-Butoxy-l-phenyl-1-trimethylstannylcyclopropane (141).

5 143

lÀJ V

PPM

Figure 35. 300 MHz 1 H-NMR of (E)-2,4-Dihydropyrany!-1-pheny!-1-trimethylstannylcycloprDpane (143). 1 4 3

JU il» I *4v/v»*^V II I r«Lf^

■■"I " ' I ' ' ' ' ' ' ' I ’•T” "I"' I ' I" '-T' I ...... I...... '""I...... 90 80 30 20 0 140 130 ISO 110 100 '%PM 50 ^0 10 0 -10

Figure 36. 75 MHz ^^c-NMR of (E)-2,4-Dihydropyranyl-1-plienyl-1-trimethylstannylcyclopropane (143).

w U1 J i L JU JL iilL. u

■7--p-»— r-T * -t—T— , 1 — I - I 1 ■ , -1-1'-' -r-r-r-r—r-n-T—r- I I I I I I T ’ — » r “ 1 " I ' r I ‘ i‘ I I I I i - > I - T —1— r - r —p ~ r * -T—1—|"i I—n —, 1 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 .5 0.0 PPM

Figure 37. 300 MHz ^H-NMR of 2,2-Dimethoxy-1-trlmethylstannyl-1-pheny!cycloprDpan8(147). '•'I ...... I ...... „ ,.,M,|,'" |" " I" " |,,,I,,'"|""I""| ...... I...... " I " ' ' " " I ' ...... "'I ...... I' M 200 leo 180 170 160 150 140 130 120 110 100^^ 90 60 70 GO 50 40 30 20 10 0 -10

Figure 38. 75 MHz ^^C-NMR of 2,2-Dlmethoxy-1-tr!m6thyistannyi-1-ph6nylcyc!opfDpane (147). CgHg— C—Sn(CeHs)i 161

5I5 nlo 4.0 3 .5 3.0 PPM

Figure 39. 250 MHz I h -NMR of Phenyl(triphenylstannyl)diazomeihane (161). CeHs— C-Pb(CeH5); 162

PPM

Figure 40. 250 MHz ^H-NMR of Phenyi(lriphenylpIumbyl)dia2omethane (162). w VO JC = N — N = C

1 7 3

, , I vf-r^j, , - r - p r - ' ' r ' ' r ' n r...... ” "f ■ ...... I ' ■**T^ 170 160 150HO 130 120 110 100 90 60 70 60 50 AO PPM

Figure 41. 63 MHz ^H-NMR Of p-Chlorobenzoylbenzaiazine (173).

ê ')C = N — N=C^ r 1 7 3

5 .5 5 .0 PPM

Figure 42. 250 MHz "'^c-NMR of p-Chiorobenzoyibenzaiazine (173). 1 7 4

8,0 7.5 /, V o«y o»v —. ppj^ - - -

Figure 43. 250 MHz ‘'H-NMR of p-Trlfiuoromethyibenzoylbenzalazine (174). ■N=C

1 7 4

~~Tr~ "-T- ’X*' -'T -"T" "T- ’T' ’T’ 'T 170 160 150 130 120 110 100 90 70 GO 50 PPM

Figure 44 63 MHz ‘•^C-NMR of p-Trifiuoromethyibenzoyibenzaiazine (174).

6 APPENDIX B

Alternative Mechanisms for Diastereoseiectivity of Metai Catalyzed Decomposition Reactions of DIazc Compounds

144 145

Discussion Concerning Metal Catalyzed Decompositon Reactions of Diazo Compounds

Mechanistic theory for additions to olefins involving metal catalyzed reactions of diazo compounds is still developing. The purpose of the following discussion is to propose alternative mechanisms from those discussed earlier to account for the stereoselectivity in reactions of diazo compounds decomposed by metal catalysts in the presence of substituted olefins.

The experimental facts are: when phenyldiazomethane is decomposed by rhodium(ll) acetate in the presence of varied substituted olefins Z cyclopropanes are formed predominately, whereas reactions of ethyl diazoacetate give E-cyclopropanes under similar conditions. Also it is found from the present research that when phenyl{trimethylstannyl)diazomethane is decomposed with rhodium(ll) acetate in the presence of vinyl ethers only E- cyclopropanes are formed. There are alternative mechanistic explanations than those proposed earlier which account for the observed diastereoseiectivity.

Since the rhodium atom is believed to play an integral role in the overall process it is presently assumed that the diazo compound reacts with rhodium(ll) acetate with loss of nitrogen to form the intermediate rhodium diazo carbon ylide (Fig 45). The ylide, then adds to the substituted olefin. The structure of

O § z y v i-# kn,.Rh,(OAc),

Figure 45. Metal Diazocarbon Ylide 146 the intermediate ylide and its subsequent interaction with the olefin then controls the course of the reaction. It is proposed that formation of the most stable rhodium diazo carbon ylide-olefin complex is favored. By most stable is meant the complex which minimizes unfavorable steric interactions and maximizes electronic effects. The rate of reaction is thus controlled by the activation energy leading to formation of the complex. Subsequent elimination of the rhodium(ll) acetate determines whether the Z- or E-cyclopropane is formed preferentially.

Formation of the most stable rhodium diazo carbon ylide-olefin complex requires that steric repulsions be at a minimal upon addition. Thus the bulky metal catalyst will be as far away from the olefin as possible. The next largest group will then be located on the side opposite to the substituent on the olefin to minimize steric interactions. Such a complex is illustrated in (Fig 46). Rotation

O LnM— "

Figure 46. Metal Diazocarbon-oiefinComple:

in the intially formed intermediate then occurs such that the negatively charged metal moiety is adjacent to the positive charge on the olefin and results in the conformation from which the metal catalyst is eliminated. The overall process 147 favors formation of Z-cyclopropanes as depicted for reactions of phenyldiazom ethane (Fig 47).

o .Ph LnM- / h H H k,M=c; + )P=C' H H H, ft R

Ph^

- ML. H

Figure 47. Most Stable Intermediate Predicts Z-Cyclopropane for Phenyldiazomethane

In reaction of ethyl diazoacetate the most stable initial complex is again formed. However because of electronic effects and steric interactions rotation of the o-bond between the rhodium diazo carbon ylid and olefin does not occur.

Instead the rhodium moiety is expelled (backs out) to form the intermediate

carbanion which is stabilized by the carbonyl group of the adduct. Hybridization

of the sp3 carbon center to sp 2 then allows attack on the positively charged

carbon of the olefin (Fig 48). 148

- ml.

C O g E t pOgEt

.COgEt

H/. L@

Figure 48. Hybridization to SpP Carbanion Predicts Formation of tfie E-Cyclopropane for Ethyl Diazoacetate

Of further interest is that phenyl(trimethylstannyl)dia 2omethane and rhodium(ll) acetate react with vinyl ethers diastereospecifically to give Z cyclopropanes. Illustration of this process using the concepts that trimethylstannyi is bulkier than phenyl and the most stable initial dipolar intermediate is formed first is shown in Fig 49. Formation of only E-cyclopro- 149

O MLn O ^n(CH3)3 LnM Sn(CH3)3 H H ■•Ph L„M=C + /C=C - H.. Ph \ Sn(CH3)3 R R ^ H

-ML,

Sn(CH3)3 Ph. ^n(CH3)3 H lO

F ig u re 49 . Hybridization to Spf Carbanion Predicts E-Cyclopropane for Phenyi(trimethyl- stannyljdiazoniethane

panes occurs since rotation of the a-bond of the rhodium diazo carbon and olefin complex does not occur because of the extreme bulk of the trimethylstannyi group. Furthermore, stabilization of the sp2 carbanion by back- bonding into the empty d-orbitals of the tin atom upon loss of the catalyst also contributes to the preferred formation of E-cyclopropanes. 150

Of further note is that steric factors in the metal diazo carbon ylide also favor initial formation of the most stable dipolar complex if the smallest group on the ylide leads the approach to the olefin thus allowing for the metal moiety to

be furthest away from the olefinic substituent. Subsequent formation of ag -

bond between the metal diazo carbon ylid and olefin would result in the most

stable complex (Fig 50).

O MLn LnM- H

Figure 50. Preferred Approach of Metal Diazocarbor to Form the Most Stable Complex

A study by Casey et al discloses that (CO) 5 WCHC 0 H5 reacts with

substituted olefins to give predominately Z-cyclopropanes.79 The model

proposed above also predicts preferential formation of Z-cyclopropanes. The

hypothesis that an intermediate puckered metallocyclobutane is involved in

these reactions was rejected by Casey because reaction of (CO) 5WCHC0 H5

with 2-methyl-2-butene gave preferentially the Z-cyclopropane. Thermo

dynamically, the E-cyclopropane would be favored if it were derived from an

intermediate metallocyclopropane. However in light of the above model for

metal diazo carbon ylid reactions, Z-cyclopropanes are expected to be favored.

Thus preferential formation of the Z-cyclopropanes occurs because of kinetic

control rather than because of thermodynamic effects. Furthermore, the highly 151 selective formation of the Z-cyclopropane (94:1 ) can also be explained by this new model. Since the carbon containing the positive charge is expected to be stabilized by the additional alkyl groups there is increased opportunity for

rotation of the o-bond between the metal diazo carbon ylide and olefin (Fig 51 ).

/ h H R (C0)5W=C( + H \ Ph

R © R

H o -W(C0)5 Ph*

W(C0)5

Ph W(CO)s o

Figure 51. Most Stable Intermediate Predicts Z Cyclopropane for W(CO) 5CH%

The following discussion has provided an alternative mechanistic

interpretation for diastereoseiectivity in metal catalyzed decomposition

reactions of diazo compounds. However more experimental research is

needed in this area to provide evidence for intermediate metal diazo carbon

and olefin complexes. REFERENCES

(1) Büchner, E. Chem. Ber. 1885, 28, 215. (2) Müller, E.; Ludsteck, D. Chem. Ber. 1954, 8 71887. , (3) Regitz, M.; W eber, B. Synthesis ^Q72, 7, 354. (4) (a) Regitz, M.; LIedhegner, A.; Eckstein, U.; Martin, M.; Anschütz, W. Liebigs Ann. Chem. 1971, 748, 207. (b) Schôlikopf, U.; Pieber, N. Chem. Ber. 1969, 102, 488. (5) Blues, E.; Smith, D.; Irwin, J.; Lawton, I. J.C.S. Chem. Comm. 1974,466. (6) Scherer, O.; Schmidt, M. Z Naturforsch. S 1 9 6 5 , 2 0 ,1009. (7) Muller, F.; Disselhoff, H. Justus Liebigs Ann. Chem. 1934, 512, 250. (8) (a) Schôlikopf, U.; Frasnelli, H. Angew. Chem. Internat. Edit. 1970, 9, 301. (b) Schôlikopf, U.; Banhidai, B.; Frasnelli, H.; Meyer, R.; Beckhaus, H. Liebigs Ann. Chem. 1974, 1767. (9) Regitz, M.; W eber, B. Synthesis^972, 7,354. (10) Schôlikopf, U.; Banhidai, B.; Frasnelli, H.; Meyer, R.; Beckhaus, H. Liebigs Ann. Chem. 1974, 1767. (11) Lorbeth, J. J. Organomet. Chem. 1971, 27, 303. (12) Kromes, P.; Lorbeth, J. J. Organomet. Chem. 1975, 93, 339. (13) Lappert, M.; Lorbeth, J.; Poland, J. J. Chem. [A] 1970, 2954. (14) Lorbeth, J. J. Organomet. Chem. 1968, 15, 251. (15) (a) Schôlikopf, U.; Banhidai, B.; Frasnelli, H.; Meyer, R.; Beckhaus, H. Liebigs Ann. Chem. 1974, 1767. (b) Schôlikopf, U.; Banhidai, B.; Schulz, H. Liebigs Ann. Chem. 1972, 761, 137. (16) (a) Schôlikopf, U.; Banhidai, B.; Schulz, H. Liebigs Ann. Chem. 1972, 761, 137. (b) Schôlikopf, U. Angew. Chem. Ed. Engi. 1967, 6, 884. (17) Lappert, M.; Lorberth, J.; Poland, J. J. Chem. Soc. [AJ197Q,2954. (18) Seyferth, D.; Flood, T. J. Organomet. Chem. 1971, C25, 29. (19) Dominh, T.; Strauz, 0.; Gunning, H. Tetrahedron Lett. 1968, 5237. (20) Seyferth, D.; Dow, A.; Menzel, H.; Flood, T. J. Amer. Chem. Soc. 1968, 9 0 , 1080. (21) Mon, S.; Sakai, I.; Aoyama, T.; Shiori, T. Chem. Pharm. Buii. 1982, 30, 3380. (22) Sekiguchi, A.; Ando, W. Organomet. 1987, 6 ,1857. (23) Brook, A.; Jones, P. Canadian Journal of Chemistry 1969, 47, 4354. (24) Kaufmann, K.; Aürath, B.; Trager, P.; Rühlmann, K. Tetrahedron Lett. 1968, 48, 4973. 152 153

(25) Kruglaya, O.; Fedot'eva, I.; Kolikhman, I.; Brodskaya, E.; Vyazankin. J. Organomet Chem. 1977,142,155. (26) Grüning, H.; Lorberth, J. J. of Organomet Chem. 1977, 129, 55. (27) (a) Gerhardt, P.; Schôlikopf, U.; Schumacher, H. Angew. Chem. Int. Ed. 1967, 6, 74. (b) Schôlikopf, U.; Gerhardt, P.; Reetz, M.; Prasnelli, H.; Schumacher, H. Liebigs Ann. Chem. 1968, 204. (c) Schôlikopf, U.,- Rieber, N. Angew Chem. Int. Ed. 1967, 6, 884. (d) Schôlikopf, U.; Hoppe, D.; Rieber, N.; Jacobi, V. Liebigs Ann. Chem. 1969, 730, 1. (e) Schôlikopf, U.; Rieber, N. 1969, 102, 488. (28) Strauz, O.; Kennepohl, G.; Gomeau, P.; Dominh, T.; Kim, B.; Valenty, S.; Skell, P. J. Amer. Chem. Soc. 1974, 96, 5723. (29 Schôlikopf, U.; Rieber, N. Chem. Ber. 1969, 102, 488. (30 Schôlikopf, U.; Prasnelli, H. Angew. Chem. Int. Ed. 1970, 9, 301. (31 Aoyama, T.; Shioiri, T. Tetrahedron Lett. 1986, 27, 2005. (32 Kruglaya, 0.; Pedot'eva, I.; Pedot'eva, B.; Kalikhman. I.; Brodskaya, E.; Vyazankin, N. J. Organomet. Chem. 1977, 142,155. (33 Kreeger, R.; Shechter, H. Tetrahedron Lett. 1975, 25, 2061. (34 Costan, P.; Bocciredo, A.; Bertrand, G. Angew. Chem. Int. Ed. Engl. 1989, 9, 28. (35 Lappert, M.; Lorbeth, J.; Poland, J. J. Chem. Soc. [A] 1970, 2954. (36 Ando, W.; Sekiguchi, A.; Hagiwara, T.; Migita, T. J.C.S. Chem. Comm. 1974, 372. (37 Barton, T.; Kilgour, J. J. Amer. Chem. Soc. 1975, 97, 657. (38 Ando, W.; Sekiguchi, A.; Ogiwara, J.; Migata, T. J.C.S. Chem. Comm. 1975, 145. (39 Jones, M.; Norsoph, E.; Coleman, B. J. Amer. Chem. Soc. 1978, 100, 994. (40 Albert, Padwa 1,3-Dipoiar Cycloaddition Chemistry 1984, Ch. f, John Wiley and Sons. (41 Huisgen, R. Angew. Chem. Int Ed. Engl. 1963, 2(10), 565. (42 Lappert, M.\ Poland, J. J.Chem. Soc.(C) 1971, 3910. (43 Pieser, L: Peters, M. J. Amer. Chem. Soc 1931, 53, 4080. (44 Seyferth, D. Chem. Reviews 1955, 5 5 ,1155. (45 Hebbe, L.; Naadkarmi, D.; Wheeler, T. J. Chem. Soc. 1938,1322. (46 Shechter, H.; Kreeger, L. Tetrahedron Lett. 1975, 25, 2061. (47 Doyle, M. Chem. Rev. 1986, 86, 919. (48 Doyle, M.; Griffin, J.; Bagheri, V.; Dorow, R. Orgsnomctaliics 1984, 3(1), 53. (49 Shankar, R.; Shechter, H. (50 Bagheri, V.; Doyle, M.; Taunton, J.; Claxton, E. J. Org. Chem. 1988, 53„ 6160. (51 Stang, P.; Learned, A. J. Amer. Chem. Soc. 1987, 109, 5020. (52 Wenkert, E. Acc. Chem. Res. 1974, 74, 431. 154

(53) Bagheri, V.; Doyle, M.;Taauton,J.; Claxton, E. J. 0/p. Chem. 1988, 53, 6160. (54) Doyle, M.; Griffin, J.; Bagheri, V.; Dorow, R. Organomet. 1984, 3(1), 53. (55) Doyle, M. Acc. Chem. Res. 1 9 8 6 , 19, 348. (56) Doyle, M. Chem. Rev. ^9Q6, 86, 919. (57) Danilkina,L; Milkina, V.; Doorokhova, O. Zhurm. Obsh. Khim. 1975, 45(9), 2014. (58) Regitz, B.; Eister, B.; Heck, G.; Schwall, H. Methods ofOrganishen Chemie 1952, 10. 710. (59) Pauson, P.; Williams, b. J. Chem. Soc. 1961, 4162. (60) Coleman, G.; Gilman, H.; Adams, C.; Pratt, P. J. Org. Chem. 1 9 3 8 , 3, 99. (61) Private Communication, Shechter, H. (62) Private Communication, Shechter, H. (63) Brook, A.; Jones, P. Canadian Journal of Chemistry 1969, 47, 4354. (64) (a) Regitz, M.; Anschutz, W. C/iem. fier. 1969,102, 2216. (b) Brook, A.; Jones, P. Canadian Journal of Chemistry 1969, 47, 4354. (65) Scheiner, P. J. Org. Chem. 1969, 3 4 ,199. (66) Huisgen, R.; Sauer, J.; Seidel, M. Ann. Chem. 1962, 6 5 4146. , (67) Friedman, L; Little, R.; Reichie, W. Org. Syn. 4 0 ,9 3 . (68) Kende, A. Org. Syn. 1985. 64, 207. (69) Kende, A. Org. Syn. 1985. 64, 207. (70) Kende, A. Org. Syn. 1985. 64, 207. (71 ) Edgell, W.; Ward, C. J. Amer. Chem. Soc. 1954, 7 61169. , (72) J. Amer. Chem. Soc. 1981, 103, 838. (73) Lappert, M.; Jones, K. J. Chem. Soc. 1965,1945. (74) Hebbe, L; Nadkarmi, D.; Wheeler, T. J.Chem. Soc. 1938,1322. (75) Brook, A.; Jones, P. Canadian Journal of Chemistry 1969, 47, 4354. (76) Brook, A.; Jo n es, P. Canadian Journal of Chemistry 1 9 6 9 , 4 7 ,4354. (77) Regitz, M.; Anschutz, W. Chem. Ber. 1969, 102, 2216. (78) Scheiner, P. J. Org. Chem. 1969, 3 4 ,199. (79) Casey, C.; Polichnowski, S.; Shusterman, A.; Jones, C. J. Amer. Chem. Soc. 1979, 101, 7282