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Arenechromium Tricarbonyl Complexes: Conformational

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η6 – ARENECHROMIUM TRICARBONYL COMPLEXES: CONFORMATIONAL ANALYSIS, STEREOCONTROL IN NUCLEOPHILIC ADDITION AND APPLICATIONS IN ORGANIC SYNTHESIS by HARINANDINI PARAMAHAMSAN Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Thesis Advisor: Prof. Anthony J. Pearson Department of Chemistry CASE WESTERN RESERVE UNIVERSITY May 2005 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the dissertation of Harinandini Paramahamsan candidate for the Ph.D. degree*. (signed) Prof. Philip P. Garner (Chair of the Committee, Department of Chemistry, CWRU) Prof. Anthony J. Pearson (Department of Chemistry, CWRU) Prof. Fred L. Urbach (Department of Chemistry, CWRU) Dr. Zwong-Wu Guo (Department of Chemistry, CWRU) Dr. Stuart J. Rowan (Department of Macromolecular Science and Engineering, CWRU) Date: 14th January 2005 *We also certify that written approval has been obtained for any propriety material contained therein. To Amma, Naina & all my Teachers Table of Contents List of Tables………………………………………………………………………..……iv List of Figures…………………………………………………………………….…........vi List of Schemes…………………………………………………………………….….….ix List of Equations………………………………………………………...……….……….xi Acknowledgements………………………………………………………….…..……….xii List of Abbreviations……………………………………………………………………xiv Abstract………………………………………………………………………………….xvi CHAPTER I........................................................................................................................ 1 I.1 Structure and Bonding ............................................................................................ 2 I.2 General Methods of Preparation ............................................................................. 3 I.3 Reactivity and Chemistry........................................................................................ 4 I.4 Illustrations of Applications in Organic Synthesis ................................................. 5 References………………………………………………………………………..10 CHAPTER II..................................................................................................................... 14 II.1 Conformational Features of Arenechromium Tricarbonyl Complexes – General and Background .................................................................................................... 15 II.2 X-ray Crystal Structure Analysis of Chiral Alkoxyarenechromium Tricarbonyl Complexes............................................................................................................. 24 II.3 Conformational Analysis of Chiral Arenechromium Tricarbonyl Complexes in Solution: Correlation to Solid State Structure and Conformation ........................ 29 i II.4 Variable Temperature NMR Studies .................................................................... 48 II.5 Conclusions........................................................................................................... 51 Experimental………………...…………………………………………………...54 Appendix to Chapter II…………………………………………………………..73 References………………………………………………………………………117 CHAPTER III ................................................................................................................. 125 III.1 Conformational Analysis of Arene Chromium Tricarbonyl Complexes............ 126 III.2 13C NMR Chemical Shifts in Conformational Analysis..................................... 131 III.3 13C NMR Complexation Shifts, Conformation and Regioselectivity of Nucleophilic Addition......................................................................................... 135 III.4 CCS in Chiral Arene Chromium Tricarbonyl Complexes.................................. 140 III.5 Conclusions......................................................................................................... 142 References…………………………………………………………………...….144 CHAPTER IV ................................................................................................................. 151 IV.1 Nucleophilic Addition to Arene Chromium Tricarbonyl Complexes – General and Background......................................................................................................... 152 IV.2 Camphor Derived Chiral Isoborneol Directed Nucleophilic Addition to Arenechromium Tricarbonyl Complexes ........................................................... 165 IV.3 Results and Discussion....................................................................................... 177 IV.4 Efforts towards Synthesis of FK-506 sub-unit.................................................... 184 ii IV.5 Conclusions......................................................................................................... 186 Experimental……………………………………………………..……………..188 References…………………………………………………………………..…..213 CHAPTER V .................................................................................................................. 224 V.1 Studies in Vicinal Stereocontrol in Nucleophilic Addition to Arenechromium Tricarbonyl Complexes....................................................................................... 225 V.2 Formal Synthesis of (±)Juvabione ...................................................................... 234 V.3 Miscellaneous Results During Stereocontrol Study ........................................... 234 V.4 Vicinal Stereocontrol and Asymmetry During Nucleophilic Addition .............. 236 V.5 Conclusions......................................................................................................... 239 Experimental…………………………………………………………...……….240 References…………………………………………………………..…………..253 APPENDIX……………………………………………………………………………..257 BIBLIOGRAPHY………………………………………………………………………324 iii List of Tables Table II.1 Torsion Angles of Tripod Rotation for the Four Complexes II.1-II.4 ............. 27 Table II.2 Arene Carbon-carbon Bond Lengths from the Crystal Structures of Complexes II.1 – II.4 ........................................................................................................................... 28 Table II.3 13C NMR Carbon Chemical Shifts at the Four Diastereotopic Arene Complexed Carbons with 13C NMR Chemical Shift Pattern and Correlation to Tripod Orientation (For explanation of A edge and B edge see Figure II.24) ............................. 46 Table III.1 Θ–Values and Populations of conformation III.B (PB) in C6H5RCr(CO)3 at 33±5 ºC ........................................................................................................................... 127 Table III.2 Complexation Shifts d1-d4 for Complexes III.1-III.6 (Cn and C’n represent the CCS of the arene and the corresponding complex respectively) .............................. 136 Table III.3 Population Pmeta (%) Compared to Regioselectivity of Nucleophilic Addition. t Nucleophile: (a) – LiCH(Me)CO2Bu (b) LiC(OR)MeCN............................................. 138 Table III.4 ∆ Values for Complexes III.1 – III.6 ............................................................ 138 Table IV.1 Regioselectivity on Nucleophilic Addition of Anions to (tert-Butylbenzene)- Cr(CO)3 ........................................................................................................................... 156 Table IV.2 Diastereoselectivity During Isobutyronitrile Anion Addition to Arenechromium Tricarbonyl Complexes with PIB-OH, MIB-OH and DOIB-OH Chiral Auxiliaries....................................................................................................................... 166 Table IV.3 Chiral C2-substituted Isoborneols Prepared from D(+) Camphor and their Yields .............................................................................................................................. 171 Table IV.4 Synthesis of Chiral Alkoxyarenechromium Tricarbonyl Complexes IV.12 by SNAr Reaction of Complex IV.11................................................................................... 174 Table IV.5 Ratio of Diastereoselectivity on Nucleophilic Addition to Chiral Arenechromium Tricarbonyl Complexes (* Major isomer presumed)........................... 178 Table IV.6 13C NMR Chemical Shifts Correlated (*Tripod orientation from X-ray crystal structures #Major isomer on tert-butyl lithio acetate addition)....................................... 187 Table V.1 Ratio of Regio- and Stereoisomeric Cyclohexadienol Ether Products from Addition of tert-Butyl Lithiopropionate to Anisole Chromium Tricarbonyl Complexes V.1- V.3 .......................................................................................................................... 227 iv Table V.2 Ratio of Regio- and Stereoselectivity in Propionitrile Anion Addition to Complexes V.1 – V.3...................................................................................................... 231 v List of Figures Figure I.1 Metal-Carbonyl Bonding ................................................................................... 2 6 Figure I.2 Molecular orbital interaction diagram of η -benzene-Cr(CO)3 complex. Reprinted with permission from (Albright, T. A.; Carpenter, B. K. Inorg. Chem. 1980, 19, 3092-3097) Copyright (1980) American Chemical Society......................................... 3 Figure I.3 Change in Arene Reactivity on Coordination with Cr(CO)3 and Planar Chirality ............................................................................................................................................. 4 Figure II.1 Conformations anti-Eclipsed and syn-Eclipsed Due to Electronic Effect of Substituents......................................................................................................................
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