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Novel Organic Transformations Arising from Gold(I) Chemistry

By

Mathieu André Morin

Thesis submitted to the faculty of Graduate and Postdoctoral Studies
In partial fulfillment of the requirements for the
Ph.D. degree in chemistry

  • Candidate
  • Supervisor

  • Mathieu André Morin
  • Dr. Louis Barriault

Ottawa-Carleton Chemistry Institute
Faculty of Science University of Ottawa

© Mathieu André Morin, Ottawa, Canada, 2017

Abstract

The use of gold in organic chemistry is a relatively recent occurrence. In addition to being previously considered too expensive, it was also believed to be chemically inert. Soon after the early reports indicating its rich reactivity, the number of reports on chemical transformations involving gold sky rocketed. One such report by Toste and coworkers demonstrated the intramolecular addition of silyl enol ether onto Au(I) activated alkynes, resulting in a 5-exo dig cyclization. The first part (Chapter 1) of this thesis discusses the development of a Au(I) catalyzed polycyclization reaction inspired by this transformation. The reaction demonstrated the ability of Au(I) to successfully catalyze the formation of multiple C-C bonds and resulted in the synthesis of benzothiophenes, benzofurans, carbazoles and hydrindene.

With the current resurgence of photochemical transformations being reported in literature, various opportunities for the use of Au(I) complexes arose. The substantial relativistic effect observed in gold which make it a good soft Lewis acid also has a significant influence on the redox potential of this metal. Chapter 3 of this thesis discusses the development of a Au(I) photocatalyzed process which benefits from having both a strong oxidation and reduction potential for the reduction of carbon-halide bonds. Radical reductions and cyclizations were accessed with the use of polynuclear Au(I) photocatalysts. In depth analysis of catalytically active Au(I) complexes helped elucidate the mechanism by which this photochemical reaction occurs. This part (Chapter 4) also covers serendipitously discovered uncatalyzed photochemical transformations derived from our work with gold. The halogenation reaction of primary alcohols was successfully achieved and a combination of our developed methods resulted in an efficient dehydroxylation protocol.

II

Acknowledgement

The time spent working towards this thesis has allowed me the pleasure of interacting with many people who have made this an enriching experience and without whose support this final product would not have been possible. I would like to first thank Prof. Louis Barriault for bringing me into the realm of chemical research. The guidance and experience I have received under his mentorship have been essential to my development as an organic chemist. I am very grateful for his willingness to place such confidence in me and allow me the freedom to pursue this new branch of chemistry with the lab.

I would also like to thank Prof. Derek Pratt for answering my many questions about chemistry. The amount of knowledge he shared with me, especially during the first years of my Ph. D. has been instrumental in solidifying my understanding of chemistry.

Merci à mes parents, Eric et Solange pour leur amour et support pendant toutes ces années. Malgré la distance ils ont toujours été présents en temps de besoin et ont toujours cru en moi.

I would like to thank numerous people both within and outside the lab for their friendship and support; Patrick Levesque for being both a wonderful teacher in the ways of chemistry and a great roommate for several years. Terry McCallum who I was fortunate enough to share many publications and many beers, I am incredibly grateful to have you as a friend and colleague. Gabriel Bellavance for great conversation both about chemistry and literally everything else (I

will get to εars….). Philippe εcGee who I was lucky enough to know since my undergraduate

studies, who has enriched my experiences in chemistry and taught me so much. Thank you to the
III many people I have interacted with throughout these many years, Spencer, J-P, Guillaume, David, Frank, Jason, Joel, Travis, Alex, Colombe, Amandine, Laurie-Anne, Julie, Mike, Huy, Sam.

From outside the lab I would like to thank my friends who had to sometimes remind me that I could talk about things other than chemistry. Jenn, Alex, Dré, J.R., Angie, Gen and Vince, with whom I have shared many great nights and stories. Thank you Alyssa for your love and patience when I go on about chemistry, I am grateful to have you in my life.

IV

Contributions to Research

Refereed Publications:

Tran, H.; McCallum, T.; Morin, M.; Barriault, δ*. ‘‘Homocoupling of Iodoarenes and Bromoalkanes Using Photoredox Gold Catalysis: A Light Enabled Au(III) Reductive Elimination’’ Org. Lett. (2016) 4308 – 4311

McTiernan, S. D.; Morin, M.; εcCallum, T.; Scaiano, J.C.*; Barriault, δ.* ‘‘Polynuclear Gold

(I) Complexes in Photoredox Catalysis: Understanding their Reactivity through Characterization and Kinetic Analysis’’ Catal. Sci. Technol. (2016) 201 – 207

McCallum, T.; Slavko, E.; Morin, M.; Barriault, δ.*; ‘‘Light-Mediated deoxygenation of alcohols with a Dimeric Gold Catalyst’’ Euro. J. Org. Chem. (2015) 81 – 85

Revol, G.; McCallum, T.; Morin, M.; Gagosz, F.*; Barriault, L.*; Photoredox Transformations with Dimeric Gold Complexes, Angew. Chem. Int. Ed. (2013),13342 – 13345

Morin, M.; Levesque, P.; Barriault, L.*; Gold(I)-catalyzed domino cyclization for the synthesis of polyaromatic heterocycles, Beilstein J. Org. Chem. (2013) 2625 – 2628

Contributing Author:

Barriault, L.; Morin, M. (2016) ‘‘The σazarov Cyclization of Cross-Conjugated Ketones’’,

Cross Conjugation: Modern Dendralene, Radialene and Fulvene Chemistry, Wiley-VCH (Eds.

Hopf, H.; Sherburn, M. ISBN: 978-3-527-33437-7)

Oral Presentations:

Revol, G.; McCallum, T.; Morin, M.*; Gagosz, F.; Barriault, δ. (2013) ‘‘Photoredox

Transformations with Dimeric Gold Complexes’’ Centre for Catalysis Research and Innovation

(Regional)

Poster Presentations:

Morin, M.*; εcCallum, T.; Barriault, δ. (2016) ‘‘εethylating with εethanol’’ Gordon

Research Conference; Natural Products & Bioactive Compounds (International)

Morin, M.*; εcCallum, T.; Barriault, δ. (2015) ‘‘δight Initiated Cascade Reaction for the

Synthesis of Polycyclic Compounds’’ International Chemical Congress of Pacific Basin Societies (International)

V

Morin, M.*; McCallum, T.; Barriault, δ. (2015) ‘‘δight Initiated Radical Polycylization of

Cyclopropyl Containing Compounds’’ 98th Canadian Chemistry Conference and Exhibition

(International)

Morin, M.*; εcCallum, T.; Barriault, δ. (2014) ‘‘Photo-Activated Gold Catalysts: Bridging

Bis-Phosphine and Bis-Carbene δigands’’ 19th International Symposium on Homogeneous Catalysis (International)

Morin, M.*; εcCallum, T.; Barriault, δ. (2013) ‘‘Photo-Activated Gold Catalysts: Light

εediated SET for Radical Formation’’ 6th Pacific Symposium on Radical Chemistry

(International)

Morin, M.*; δevesque, P.; Barriault, δ. (2012) ‘‘Heterocycle Synthesis via Au(I)/ Prins cyclisation and efforts towards synthesis of dihydrojunenol’’ Synthesis Day, Université d’Ottawa

(Regional)

Morin, M.*; Levesque, P.; Barriault, L. (2011) ‘‘Synthèse d’hétérocycles par une cascade

Au(I)/cyclisation Prins’’ 23e Colloque de Chimie de Sherbrooke (Provincial)

VI

Table of Contents
Details of Contribution ..........................................................................................XV
Introduction..........................................................................................................1

1.1 Relativistic Effect............................................................................................................. 3 1.2 Catalysis by Gold(I) Complex.......................................................................................... 4 1.3 Initial Contributions in Au(I) Chemistry........................................................................ 10

Organic Photochemistry and Photocatalysis .....................................................17

2.1. Photochemical Excitation............................................................................................... 17 2.2. Photocatalysis................................................................................................................. 19 2.3. Photocatalytic Systems................................................................................................... 21

2.3.1. 2.3.2.
Single catalyst systems........................................................................................................21 Dual catalytic photochemical processes..............................................................................25

Bi-nuclear Au(I) Photocatalysis ........................................................................32

3.1 Au2dppm2Cl2 .................................................................................................................. 32 3.2 Photocatalyzed Reduction of Halocarbon Bonds........................................................... 34

3.2.1 3.2.2 3.2.3
Reduction of unactivated bromoalkanes .............................................................................36 Reduction of bromoarenes ..................................................................................................38 Photocatalyzed intermolecular radical addition..................................................................40

3.3 Further Development of Au(I) Photochemical Reduction ............................................. 42 3.4 Mechanistic Investigation .............................................................................................. 47

3.4.1 3.4.2 3.4.3 3.4.4
Chemical compatibility of polynuclear Au(I) complexes...................................................48 Oxidation and reduction potentials .....................................................................................51 Oxidative vs reductive quenching.......................................................................................54 Substrate pre-association.....................................................................................................60

3.5 Homocoupling of Halocarbons ...................................................................................... 62

3.5.1 Photocatalytic arene dimerization.......................................................................................63

3.6 Summary of findings in polynuclear Au(I) Photocatalysis............................................ 68

Uncatalyzed Photoactivation.............................................................................72

4.1 Bromination of Alcohols................................................................................................ 72

4.1.1 4.1.2
Photolysis of CBr4...............................................................................................................73 One-Pot Radical Reduction.................................................................................................78

VII
4.2 Methylation with Methanol............................................................................................ 81

4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6
Photo-mediated alkylation of heterocycles .........................................................................82 Sulfonyl chloride and sulfonic acid ....................................................................................84 Alpha-hydroxy radical ........................................................................................................86 C-O Bond Reduction...........................................................................................................89 Searching for solutions with flow chemistry ......................................................................95 Ongoing work on methylating with methanol ....................................................................97

Supplemental Information (by Chapter)............................................................99

5.1 General Information....................................................................................................... 99 5.2 Supplemental Information Chapter 1........................................................................... 100 5.3 Supplemental Information Chapter 3........................................................................... 114

Lighting apparatus for section 3...............................................................................133

Supplemental results for background and benchmark tests for Chapter 3.2:....................135 Compounds and supplemental information for Chapter 3.3 .............................................139 Compounds and supplemental information for Chapter 3.4 .............................................140

Absorption Spectra of Aux Complexes.......................................................................145 77K Phosphorescence spectra of Aux complexes .....................................................147 Laser flash photolysis data of the Aux complexes .....................................................150 Cyclic voltametry measurements of the Aux complexes ............................................165

Compounds and supplemental information for Chapter 3.5 .............................................171

5.3.1.1

5.3.2 5.3.3 5.3.4

5.3.4.1 5.3.4.2 5.3.4.3 5.3.4.4

5.3.5

5.4 Supplemental Information Chapter 4........................................................................... 183

5.4.1 5.4.2
Compounds and supplemental information for Chapter 4.1 .............................................183 Compounds for Chapter 4.2..............................................................................................194

Schemes

Scheme 1.1: Nobel prizes awarded for metal-catalyzed transformations....................................... 1 Scheme 1.2 : First examples of gold-catalyzed transformations .................................................... 2 Scheme 1.3: Generalized Au(I) Lewis acid catalytic cycle ............................................................ 5 Scheme 1.4: Example of substituent effect on Au(I) catalyzed on 5-exo/6-endo selectivity......... 7 Scheme 1.5: Substrate dependant 5-exo/6-endo cyclization........................................................... 7

VIII
Scheme 1.6: Ligand induced selectivity of [4+2] vs. [4+3] cycloisomerization ............................ 8 Scheme 1.7 : Ligand induced selectivity of [4+2] vs. [4+3] and [2+2] vs. [3+2] cycloaddition.... 9 Scheme 1.8 : Ligand controlled 6-endo vs. 5-exo cyclization of cyclic enol ethers..................... 10 Scheme 1.9 : Proposed mechanism for the formation of product 1.9.4........................................ 11 Scheme 1.10 : Alternate mechanism for the formation of 1.9.4................................................... 12 Scheme 1.11 : Synthesis of substrates F1.2.1............................................................................... 13 Scheme 2.1 : Generalized photoredox catalytic cycle. ................................................................. 21 Scheme 2.2 : Proposed photocatalytic cycle for the hydrofunctionalization of alkenes. ............. 22 Scheme 2.3: Proposed mechanism for the photocatalyzed reduction of enones. ......................... 23 Scheme 2.4 : Proposed mechanism for the reduction of carbon iodide bonds. ............................ 24 Scheme 2.5 : Proposed mechanism for the reduction of 4-nitrobenzyl bromide.......................... 25 Scheme 2.6 : Proposed mechanism for the dual catalytic Ni/Ir system........................................ 26 Scheme 2.7 : Proposed dual catalytic cycle for the Au/Ir system................................................. 27 Scheme 2.8 : Proposed mechanism for the semi-pinacol rearrangement in the dual catalytic Au/Ru system................................................................................................................................ 28

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    SCIENCE CHINA Chemistry • REVIEWS • August 2015 Vol.58 No.8: 1252–1265 · SPECIAL ISSUE · CH bond activation doi: 10.1007/s11426-015-5362-5 Directing group-assisted transition-metal-catalyzed vinylic C–H bond functionalization Kang Wang, Fangdong Hu, Yan Zhang & Jianbo Wang* Beijing National Laboratory of Molecular Sciences (BNLMS); Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education; College of Chemistry, Peking University, Beijing 100871, China Received January 8, 2015; accepted January 27, 2015; published online April 8, 2015 Transition-metal-catalyzed C–H bond activation represents one of the most attractive research areas in organic synthesis. In contrast to the great developments made in directed C–H bond functionalization of arenes, the directing group-assisted activa- tion of non-aromatic vinylic C–H bonds still remains challenging. During the recent years, significant progress has been made in this fascinating field with various functionalized alkenes, heterocycles and carbocycles being obtained. This article will fo- cus on the recent achievements in the field of directing-group-assisted vinylic C–H bond functionalization. transition-metal-catalysis, organic synthesis, C–H bond functionalization, vinylic C–H bond 1 Introduction seen for alkenes. And the electron-withdrawing DG is not contributive either (Scheme 1(b)). Besides, the substituents on the double bond may bring in steric hindrance for the The transition-metal-catalyzed activation of C–H bond is reaction on C–H bond. one of the most attractive research fields in modern organic Owing to the diverse reactivity of alkenes, the vinylic synthesis [1]. The C–H bond activation of cost-effective C–H bond activation would be appealing as on efficient tool hydrocarbons can obviate troublesome prefunctionalization for organic synthesis, while it remains less developed.
  • Towards Nickel Boride Catalyzed C-C Coupling Reactions

    Towards Nickel Boride Catalyzed C-C Coupling Reactions

    KTH Royal Institute of Technology KD200X - Master Thesis Towards nickel boride catalyzed C-C coupling reactions Author: Supervisor: Agnes Lako Professor Peter Diner July 10, 2017 Abstract This thesis focuses on the study of nickel boride as a catalyst in various coupling reactions. The nickel boride catalyst was investigated in three different coupling re- actions, the experiments aimed at understanding the activity and catalytic properties of nickel boride. We successfully synthetized the nickel boride catalyst, alongside with the cobalt and iron boride. Different methods of preparation were compared and we concluded, that the differences in the preparation, such as solvent and atmosphere, influence the activity of the catalyst in coupling reactions. We found that the most suitable solvent for preparing nickel boride is anhydrous methanol, thus we proceeded our research with this catalyst. In the case of the Sonogashira cross-coupling we found that the homocoupling of the acetylene starting material is a side reaction we could not exclude. However, with the proper solvent it is possible to shift the reaction towards homocoupling, without the formation of the heterocoupling product. Thus, we decided to investigate the Glaser homocoupling between acetylenes. In the case of the Sonogashira coupling only TLC was used to examine the reaction mixture. However, in the case of Glaser coupling, after pre-investigations we developed a gas chromatography method for analyzing the reaction mixtures. We learned, that the homocoupling only results in trace amounts (2-4%) of product. Previous investigations in our research group showed, that the nickel boride could catalyze Suzuki-Miyaura-type couplings. Examining this reaction all three metal borides were tested; however the reactions only led to the desired product with nickel boride.
  • Synthesis, Characterization, and Reactivity of Cross-Conjugated Frameworks

    Synthesis, Characterization, and Reactivity of Cross-Conjugated Frameworks

    SYNTHESIS, CHARACTERIZATION, AND REACTIVITY OF CROSS-CONJUGATED FRAMEWORKS by Victoria Leigh Hamilton A thesis submitted to the faculty of The University of North Carolina at Charlotte in partial fulfillment of the requirements for the degree of Master of Science in Chemistry Charlotte 2018 Approved by: ______________________________ Markus Etzkorn ______________________________ Craig Ogle ______________________________ Christopher Bejger ______________________________ Douglas Shafer ii ©2018 Victoria Leigh Hamilton ALL RIGHTS RESERVED iii ABSTRACT VICTORIA LEIGH HAMILTON. Synthesis, Characterization, and Reactivity of Cross-Conjugated Frameworks. (Under the direction of DR. MARKUS ETZKORN) Molecules with cross-conjugated -systems possess unique structures and reactivity due to their distinctive form of conjugation that fundamentally differs from the isomeric through conjugated systems by atom connectivity. Many of the organic compounds that played a vital role in the development of industrial organic chemistry are cross-conjugated systems or were transformed to cross-conjugated organic salts (e.g., dyes such as indigo). Our larger goal to synthesize novel cross-conjugated frameworks with potential for biological or materials applications, depended on a preparative scale synthesis of necessary precursors. We prepared a small library of arene-substituted isoindanone derivatives that necessitated optimization of synthetic routes according to electronic demands of the individual systems. Reproducible routes were actualized to afford multigram