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Design, Synthesis and Testing of New Chiral Sulfide Catalysts for Corey- Chaykovsky Reaction

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Design, Synthesis and Testing of New Chiral Sulfide Catalysts for Corey- Chaykovsky Reaction DESIGN, SYNTHESIS AND VESA TESTING OF NEW CHIRAL MYLLYMÄKI SULFIDE CATALYSTS FOR Department of Chemistry, COREY-CHAYKOVSKY University of Oulu REACTION OULU 2001 VESA MYLLYMÄKI DESIGN, SYNTHESIS AND TESTING OF NEW CHIRAL SULFIDE CATALYSTS FOR COREY- CHAYKOVSKY REACTION Academic Dissertation to be presented with the assent of the Faculty of Science, University of Oulu, for public discussion in Raahensali (Auditorium L10), Linnanmaa, on December 5th, 2001, at 12 noon. OULUN YLIOPISTO, OULU 2001 Copyright © 2001 University of Oulu, 2001 Manuscript received 16 November 2001 Manuscript accepted 19 November 2001 Communicated by Professor Liisa Kanerva Professor Tapio Hase ISBN 951-42-6571-8 (URL: http://herkules.oulu.fi/isbn9514265718/) ALSO AVAILABLE IN PRINTED FORMAT ISBN 951-42-6570-X ISSN 0355-3191 (URL: http://herkules.oulu.fi/issn03553191/) OULU UNIVERSITY PRESS OULU 2001 Myllymäki, Vesa, Design, synthesis and testing of new chiral sulfide catalysts for Corey-Chaykovsky reaction Department of Chemistry, University of Oulu, P.O.Box 3000, FIN-90014 University of Oulu, Finland 2001 Oulu, Finland (Manuscript received 16 November 2001) Abstract The first part of this monograph discusses the asymmetric, ylide based, reagent controlled epoxidations. Both different chiral ylides and epoxidation processes, stoichiometric and catalytic, are reviewed. In the following part, new chiral sulfide catalysts were discovered as enantioselective catalysts for the Corey-Chaykovsky reaction (epoxidation of aldehydes via sulfonium ylides). Using a crystal structure of an oxazolidine derivative as a starting point, a thiazolidine ligand family was designed, synthesized and finally employed as catalysts in the asymmetric epoxidation of benzaldehyde. The ligands were prepared starting from L-valine, L-tert-leucine, D-penicillamine and L-cysteine. The differently tuned thiazolidine ligands were demonstrated to catalyze the formation of trans-stilbene oxide with varying enantioselectivities. On the basis of these results, a mechanistic rationale for the asymmetric induction was presented. The results heavily demonstrated the importance of ring rigidity as an affecting factor in the enantioselectivity of the tested thiazolidines. Keywords: Corey-Chaykovsky reaction, catalysis, epoxidation, thiazolidines, ylides, enan- tioselectivity, sulfides To my Mother Acknowledgements The present study was carried out in the Department of Chemistry at the University of Oulu in 1997-2001. Part of the work was also carried out in the Laboratory for Organic Chemistry, Helsinki University of Technology, during the years 2000-2001. I thank Head of Department, Professor Jouni Pursiainen, University of Oulu, as well as Head of Department, Professor Jukka Seppälä, for allowing me to use the facilities of the department. I am grateful to my supervisor Professor Ari Koskinen for his guidance and advice throughout the research. It was you, who finally catalyzed me to finish off this work. I am indepted to referees, Professor Tapio Hase and Professor Liisa Kanerva, for their careful reading of my manuscript and Petri Moilanen for revising the language of my thesis. My sincere thanks go to all members of the Koskinen Group and Lajunen Group. In particular, I want to thank Professor Marja Lajunen for her help, friendship and motherly care. Special thanks go to Mika Lindvall for his friendship and fruitful co-operation in our common research project, to my undergraduate student Tomi Heikkinen, as well as to Teemu Törmänen and Johanna Kemppainen for their contribution to my work. I want to thank Markku Lämsä for his friendship and support during this study. Tatja, Mirka, Timo, Olli, Sulo, Janne and Miia are acknowledged as reliable mates at coffee times. Petri does not drink coffee, but was always ready for long, strategic discussions. I thank all the staff in the Department of Chemistry for the support they gave me. Especially, I wish to thank Seppo and Martti for building up a Kugelrohr-apparatus for me. Special thanks to Professor Varindel K. Aggarwal for the chemical samples that allowed us to reproduce his experiments and thus to test our experimental setup. My warmest thanks go to my mother for all her support and care during all these years. Mika & Sirpa, Paula & Jouni, and Katja, thank you for your love and support. Funding and financial support provided by Neste Oy, TEKES, Neste Research Foundation, Tauno Tönning Foundation, the University of Oulu and Emil Aaltonen Foundation is gratefully acknowledged. Oulu, November 2001 Vesa Myllymäki Symbols and abbreviations acac acetylacetonate 9-BBN 9-borabicyclo[3.3.0]nonane Bn benzyl BOC t-butoxycarbonyl Bz benzoyl CBz benxyloxycarbonyl m-CPBA m-chlorobenzoic acid DBU 1,8-diazabicyclo[5.4.0]undec-7-ene DIAD diisopropyl diazodicarboxylate DIBAL-H diisobutylaluminium hydride DIPEA diisopropylethylamine DMAP 4-dimethylaminopyridine ee enantiomeric excess MTBE methyl-t-butylether TFA trifluoroacetic acid TMEDA N,N,N’,N’-tetramethylethylenediamine Contents Abstract Acknowledgements Symbols and abbreviations Contents Preface 1 Asymmetric ylide based reagent controlled epoxidations ..............................................15 1.1 General ..................................................................................................................15 1.2 General description of the reaction.......................................................................16 1.3 Chiral sulfonium ylides ........................................................................................18 1.3.1 Trost.............................................................................................................18 1.3.2 Furukawa .....................................................................................................19 1.3.3 Durst ............................................................................................................21 1.3.3.1 C2 symmetric sulfide ligands .........................................................21 1.3.3.2 Camphor acid based non-C2 symmetric sulfide ligands...................23 1.3.3.3 Asymmetric induction .....................................................................25 1.3.4 Solladié-Cavallo ..........................................................................................27 1.3.4.1 Ligand and asymmetric induction ...................................................27 1.3.4.2 Exploitation of the results ...............................................................30 1.3.5 Dai ...................................................................................33 1.3.5.1 Stoichiometric enantioselective epoxidations..................................34 1.3.5.2 Catalytic enantioselective epoxidation ............................................37 1.3.6 Metzner ...................................................................................39 1.3.6.1 C2 symmetric sulfide ligand.............................................................39 1.3.6.2 Asymmetric induction .....................................................................41 1.3.7 Aggarwal ...................................................................................42 1.3.7.1 Development of a catalytic cycle.....................................................44 1.3.7.2 Choice of aldehyde ......................................................................48 1.3.7.3 Choice and generation of diazo compound......................................48 1.3.7.3.1 Preparation of phenyl diazomethane ...............................49 1.3.7.3.2 Generation of diazo compound in situ ..............................49 1.3.7.4 Choice of sulfide..............................................................................53 1.3.7.4.1 Employment of Durst's sulfides in catalytic cycle ............53 1.3.7.4.2 Design, preparation and testing of oxathiane ligand family ..................................................................54 1.3.7.4.2.1 Origin of diastereoselectivity .........................61 1.3.7.4.2.2 Origin of enantioselectivity............................63 1.3.7.4.3. [2.2.1] bicyclic sulfide ..................................................69 1.3.7.5. Choice of metal catalyst................................................................71 1.3.7.6. Choice of solvent ..........................................................................74 1.3.7.7. Application to ketones ..................................................................75 1.3.7.8. Application of Simmons-Smith epoxidation.................................75 1.4. Chiral aminosulfonium ylides..............................................................................78 1.5. Chiral arsonium ylides .......................................................................................81 1.6. Related reagents...................................................................................................83 1.7. Concluding remarks.............................................................................................86 2. Design, synthesis and testing of new chiral sulfide ligands for the Corey-Chaykovsky reaction ......................................................................................87 2.1. Project background ..............................................................................................87 2.2. Ligand design.......................................................................................................88 2.2.1. Structural requirements..............................................................................88
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