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And Geminal Bis(Boronic) Esters Platinum-Catalyzed Enantioselective Diboration of 1,3-Dienes and Imines and Functionalization of 1,2- and Geminal Bis(boronic) Esters Author: Kai Hong Persistent link: http://hdl.handle.net/2345/bc-ir:104130 This work is posted on eScholarship@BC, Boston College University Libraries. Boston College Electronic Thesis or Dissertation, 2015 Copyright is held by the author, with all rights reserved, unless otherwise noted. Boston College The Graduate School of Arts and Sciences Department of Chemistry PLATINUM-CATALYZED ENANTIOSELECTIVE DIBORATION OF 1,3-DIENES AND IMINES AND FUNCTIONALIZATION OF 1,2- AND GEMINAL BIS(BORONIC) ESTERS a dissertation by KAI HONG submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy May 2015 © copyright by KAI HONG 2015 PLATINUM-CATALYZED ENANTIOSELECTIVE DIBORATION OF 1,3-DIENES AND IMINES AND FUNCTIONALIZATION OF 1,2- AND GEMINAL BIS(BORONIC) ESTERS by KAI HONG Dissertation Advisor: Professor James P. Morken ABSTRACT: Platinum-catalyzed enantioselective 1,4-diboration of cyclic 1,3-dienes is reported, providing enantioenriched 1,4-bis(boronic) esters in good yield and up to 96:4 er. The analogous diboration reaction of imines generated enantioenriched α-amino boronic esters, which are valuable therapeutic candidates and useful synthetic building blocks. -Substituted allyl bis(boronic) esters, which are derived from 1,2-diboration of 1,3-dienes, undergo double allylation with 1,4-dicarbonyls to afford cyclic 1,4-diols bearing four contiguous stereocenters in a one-pot fashion with moderate to excellent diastereoselectivity. The development of a synthesis of geminal bis(boronic) esters is disclosed. These unique compounds were utilized in an alkoxide-promoted deborylative alkylation to access primary, secondary and tertiary boronic esters. Dedicated to: My Wife, Yang Wei, for her love, patience and support i ACKNOWLEDGEMENTS First and foremost, I would like to thank my advisor, Professor Jim Morken, for his continuous guidance, encouragement, support and patience during my time at Boston College. His extraordinary wealth of scientific knowledge has helped me overcome many difficult situations and his passion for chemistry has inspired me to become a self-motivated chemist. I would like to express sincere gratitude to Professor Amir Hoveyda and Professor Shih-Yuan Liu for their input as my committee members. I am also grateful to Dr. Kian L. Tan and Professor Larry T. Scott for their guidance and valuable discussions in the past few years. I would like to thank all the former and current Morken group members. I am especially thankful to Dr. Laura Kliman and Dr. Hee Yeon Cho for instruction when I was a first year student. Dr. Grace E. Ferris has been a great team member and the collaboration with her was a great experience. I am thankful to Xun Liu who has made considerable contributions to the last chapter of this dissertation. I would also like to thank a number of friends, especially Dr. Ping Zhang and Dr. Jing He who have helped me through the most challenging time. Xixi Sun, Nanjun Liu, Zhiyong Yu and Miao Yu, thank you for all the help, laughs and great memories. Finally, I am forever indebted to my mom and my wife Yang Wei. None of this work would have been possible without your endless love, unconditional support, understanding and patience. ii TABLE OF CONTENTS List of Schemes ................................................................................................................. ix List of Tables .................................................................................................................... xv List of Figures ................................................................................................................. xvi List of Abbreviations ..................................................................................................... xvii Chapter 1. Development of the Catalytic Enantioselective 1,4-Diboration of 1,3-Cyclic Dienes ............................................................................................................... 1 1.1 Introduction ...................................................................................................... 1 1.2 Background ....................................................................................................... 8 1.3 Development of Catalytic Enantioselective 1,4-Diboration of 1,3-Cyclic Dienes ...................................................................................................................... 18 1.4 Product Utility in Catalytic Enantioselective 1,4-Diboration of 1,3-Dienes .. 24 1.5 Conclusions .................................................................................................... 26 1.6 Experimental Section ...................................................................................... 27 1.6.1 General Information .......................................................................... 27 1.6.2 Preparation of Pt(dba)3 ...................................................................... 28 1.6.3 Ligand Synthesis ............................................................................... 29 1.6.4 Preparation of 2-Substituted Cyclic 1,3-Diene Substrates ................ 34 1.6.5 Representative Procedure for Diene Diboration/Oxidation .............. 42 iii 1.6.6 Characterization and Proof of Stereochemistry ................................. 43 1.6.7 Procedure for Diene Diboration/Homologation/Oxidation ............... 60 1.6.8 Procedure for Diene Diboration/Allylation/Oxidation ...................... 63 Chapter 2. Development of Catalytic Enantioselective One-pot Aminoborylation of Aromatic Aldehydes ........................................................................................................ 70 2.1 Introduction .................................................................................................... 70 2.2 Background ..................................................................................................... 75 2.3 Development of Catalytic Enantioselective One-pot Amino- borylation of Aromatic Aldehydes................................................................................................. 82 2.3.1 Preliminary Experiments of Pt-Catalyzed Diboration of N-Pivaloyl Imine ............................................................................................................... 82 2.3.2 Diboration of Imines with Different Protecting Groups .................... 85 2.3.3 N-Silyl Imine Diboration/Acylation Strategy and Ligand Optimization …………………………………………………………………………….87 2.3.4 One-pot Aminoborylation of Aldehyde and Substrate Scope ........... 90 2.3.5 Direct Introduction of Peptidic Groups during Acylation ................. 97 2.3.6 Synthetic Utilities of N-Acyl -Amino Boronic Esters and Rationale of Their Unique Stability ................................................................................ 99 iv 2.4 Conclusion .................................................................................................... 102 2.5 Experimental Section .................................................................................... 103 2.5.1 General Information ........................................................................ 103 2.5.2 Preparation of Pt(dba)3 .................................................................... 105 2.5.3 Ligand Synthesis ............................................................................. 106 2.5.4 Preparation of N-Trimethylsilyl Imines ........................................... 109 2.5.5 Representative Procedure for N-Silyl Imine Diboration/Acylation (Table 2.2) ......................................................................................................110 2.5.6 Representative Procedure for N-Silyl Imine Synthesis/Diboration/ Acylation (Scheme 2.15) ............................................................................... 111 2.5.7 Full Characterization of Products and Proof of Stereochemistry .....114 2.5.8 Imine Diboration/Acylation with Acid Fluoride ............................. 143 2.5.9 Synthesis of Boronic Acid ............................................................... 147 2.5.10 Stereospecific Suzuki-Miyaura Coupling ....................................... 149 Chapter 3. Development of Catalytic Enantioselective Tandem Allylation Strategy for the Rapid Construction of 1,4-Cyclohexanediols ................................................. 154 3.1 Introduction .................................................................................................. 154 3.2 Background ................................................................................................... 159 v 3.2.1 Type I Double Allylation Reagents ................................................. 160 3.2.2 Type II Double Allylation Reagents ................................................ 168 3.2.3 Type III Double Allylation Reagents ............................................... 169 3.3 Development of Enantioselective Tandem Diboration/Allylation of 1,4-Dicarbonyl Compounds ................................................................................... 174 3.3.1 Double Allylation of Symmetrical 1,4-Dialdehydes ....................... 174 3.3.2 Double Allylation of Unsymmetrical 1,4-Dicarbonyls ................... 181 3.4 Analysis of the Diastereoselectivity Model for the Double Allylation ........ 184 3.5 Conclusion ...................................................................................................
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