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Applications of Hypervalent Iodine Reagents in Organic Synthesis: the Development of Iodonium Metathesis Reaction and Effort Towards Himandrine

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Applications of Hypervalent Iodine Reagents in Organic Synthesis: the Development of Iodonium Metathesis Reaction and Effort Towards Himandrine APPLICATIONS OF HYPERVALENT IODINE REAGENTS IN ORGANIC SYNTHESIS: THE DEVELOPMENT OF IODONIUM METATHESIS REACTION AND EFFORT TOWARDS HIMANDRINE by Takahito Kasahara A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Chemistry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) October 2015 © Takahito Kasahara, 2015 Abstract This thesis discloses two different applications of hypervalent iodine(III) reagents in organic synthesis. In the first part, a novel reactivity of diaryliodonium triflates towards aryl iodides will be discussed. The new mode of reactivity allows various diaryliodonium triflates to be accessed, simply by heating a mixture of electron deficient diaryliodonium triflate with a moderately electron rich aryliodide. In the second part of the thesis, the use of (diacetoxyiodo)benzene in oxidative amidation in the context of total synthesis will be made. ii Preface The thesis is written by, and is based on experiments conducted by Kasahara, T. Professor Ciufolini, M. A. provided the overall synthetic strategy and tactic, helpful suggestions, and thorough editing of the thesis. The research reported in Chapter 1 has been published in: Kasahara,T.; Jang, Y. J.; Racicot, L.; Panagopoulos, D.; Liang, S. H.; Ciufolini M. A. Angew. Chem. Int. Ed. 2014, 53, 9637. Professor Ciufolini, M. A. wrote the manuscript, Kasahara, T. and Racicot, L. wrote the supporting information. The data shown in Table 1.1 and 1.2 are based on experiments performed by Racicot, L. The results shown in Scheme 1.15 are based on experiments peformed by Jang, Y. J. Semi-empirical calculations (HyperChem) shown in Figure 1.6 was performed by Professor Ciufolini, M. A. A portion of the research reported in Chapter 2 has been published in: Kasahara, T.; Ciufolini, M. A. Can. J. Chem. 2013, 91, 82. Professor Ciufolini, M. A. wrote the manuscript and Kasahara, T. wrote the supporting information. All experiments were performed by Kasahara, T. iii Table of Contents Abstract .......................................................................................................................................... ii Preface ........................................................................................................................................... iii Table of Contents ......................................................................................................................... iv List of Tables ............................................................................................................................... vii List of Figures ............................................................................................................................. viii List of Schemes ............................................................................................................................. ix List of Abbreviations ................................................................................................................. xiii Acknowledgements .................................................................................................................. xviii Chapter 1 The Development of Iodonium Metathesis Reaction .................................................. 1 1.1 Hypervalent iodine compounds: general aspects .............................................................. 1 1.2 Diaryliodonium salts ......................................................................................................... 5 1.2.1 Preparation of diaryliodonium salts .......................................................................... 6 1.2.2 Synthetic applications of diaryliodonium salts ......................................................... 8 1.3 The development of iodonium metathesis reaction .......................................................... 9 1.3.1 Inception of project ................................................................................................... 9 1.3.2 Iodonium metathesis ............................................................................................... 14 1.4 Conclusion ...................................................................................................................... 23 1.5 Experimental ................................................................................................................... 24 iv Chapter 2 Synthetic Studies Towards Himandrine .................................................................... 31 2.1 Introduction ..................................................................................................................... 31 2.1.1 The oxidative amidation of phenols ........................................................................ 31 2.1.2 Desymmetrization of dienones obtained though oxidative amidation .................... 34 2.1.3 Isolation and biological properties of (−)-himandrine ............................................ 39 2.1.4 Biosynthesis of himandrine ..................................................................................... 41 2.2 Synthetic efforts towards himandrine ............................................................................ 42 2.2.1 Mander’s approach to the framework of himandrine .............................................. 43 2.2.2 Movassaghi's total synthesis of (–)-himandrine ...................................................... 46 2.3 Prior work from the Ciufolini group ............................................................................... 51 2.3.1 Retrosynthetic considerations ................................................................................. 51 2.3.2 Preliminary results .................................................................................................. 53 2.4 An approach to himandrine via the oxidative amidation of a phenol ............................. 55 2.4.1 Directing effect of a C3 pyrrolidine substituent ...................................................... 56 2.4.2 Formation of ring C: conjugate addition strategy ................................................... 62 2.4.3. Formation of ring C: hydroacylation strategy ........................................................ 64 2.5 An advanced synthetic intermediate for himandrine ...................................................... 67 2.5.1 Tandem oxidative cyclization-IMDA-epimerization sequence with 2.166 ............ 69 2.5.2 Identification of a suitable forerunner of the MeO group of himandrine ............... 73 2.5.3 Methodology for the creation of ring D of himandrine .......................................... 77 v 2.5.4 Early-stage installation of the C5 alkyne substituent .............................................. 80 2.5.5 Elaboration of 2.222 to a precursor of himandrine incorporating ring D ............... 87 2.6 Summary and outlook ..................................................................................................... 93 2.7 Experimental ................................................................................................................... 95 References .................................................................................................................................. 147 Appendix A ................................................................................................................................ 155 Appendix B ................................................................................................................................ 164 Appendix C ................................................................................................................................ 216 vi List of Tables Table 1.1 Screening of conditions for diaryliodonium metathesis reaction ................................ 14 Table 1.2 Survey of aryl iodide for the diaryliodonium metathesis reaction............................... 16 Table 1.3 Iodonium metathesis reaction using 1.40a and 1.40b ................................................. 18 vii List of Figures Figure 1.1 Examples of organoiodine compounds at the oxidation state of −1 ............................. 1 Figure 1.2 Examples of hypervalent iodine compounds ................................................................ 1 Figure 1.3 Nomenclature of hypervalent iodine compounds ......................................................... 2 Figure 1.4 3c-4e bond of a generic hypervalent iodine compound IL3 ......................................... 3 Figure 1.5 Neutral and ionic depiction of a generic diaryliodonium salt ...................................... 6 Figure 1.6 Calculated values of partial positive charge residing on the iodine atom .................. 22 Figure 2.1 Structure of the alkaloid, himandrine ......................................................................... 31 Figure 2.2 Structures of (−)-himandrine depicted in different perspective ................................. 40 Figure 2.3 Structures of (+)-himbacine and ent-himbacine derivatives ...................................... 41 Figure 2.4 Comparison of stereochemical outcome of dienone 2.99 and 2.105 from the IMDA reaction ....................................................................................................................... 61 1 Figure 2.5 H NMR (CD3CN, 300 MHz) of (a) pure 2.243 (b) crude mixture obtained after treating 2.243 with SmI2 and (c) crude mixture after treatment with DMP ............... 92 Figure 2.6 HSQC and HMBC plot indicating the
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