The Synthesis and Reactions of Silylaziridines

Open Research Online The Open University’s repository of research publications and other research outputs The Synthesis and Reactions of Silylaziridines Thesis How to cite: Katampe, Ibrahim (2000). The Synthesis and Reactions of Silylaziridines. PhD thesis The Open University. For guidance on citations see FAQs. c 1998 Ibrahim Katampe https://creativecommons.org/licenses/by-nc-nd/4.0/ Version: Version of Record Link(s) to article on publisher’s website: http://dx.doi.org/doi:10.21954/ou.ro.0000f95c Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyright owners. For more information on Open Research Online’s data policy on reuse of materials please consult the policies page. oro.open.ac.uk ONeôSTÛDeO THE SYNTHESIS AND REACTIONS OF SILYLAZIRIDINES Thesis submitted by Ibrahim Katampe for the degree uf Doctor of Philosophy 1997 Department of Chemistry The Open University Milton Keynes England 2 ( t, m m 2 0 0 0 ProQuest Number: C805165 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest C805165 Published by ProQuest LLO (2019). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLO. ProQuest LLO. 789 East Eisenhower Parkway P.Q. Box 1346 Ann Arbor, Ml 48106- 1346 ACKNOWLEDGEMENTS I would like to express my sincere thanks to Dr. Alan Bassindale and Dr. Peter Taylor for their constant support and guidance throughout the period of my research. I acknowledge with gratitude the support of the technical staff at the Open University, Chemistry Department, in particular Mr. Pravin Patel, Mr. Gordon Howell, Mr. Jim Gibbs and Mr. Alan Leslie. My sincere thanks are also extended to the Open University for providing the funding and facilities for this research. I would like to express my sincere thanks to my dear wife Angela and daughter Stephanie, for their support and understanding. Finally, I would like to thank the Almighty God for making this possible. DECLARATION Part of this Thesis has been published in the J. Chem. Soc. Perkin Trans. 1996, 327. I grant powers of discretion to the University Librarian to allow this Thesis to be copied in whole or in part without further reference to me. This permission covers only single copies made for the purpose of study or research, subject to the normal condition of acknowledgment. m TABLE OF CONTENTS Title Page i Acknowledgements ü Déclaration iü Contents iv Abstract xiii Chapter One: INTRODUCTION 1.1 Organosilicon compounds in organic synthesis 1 1.1.1 Physical properties o f organosilicon compounds 2 1.1.2 Directive effects of the silyl group 6 1.2 The chemistry of vinylsilanes 8 1.2.1 Synthesis o f vinylsilahes 13 1.3 The chemistry of allylsilanes 17 1.3.1 Synthesis of allylsilanes 23 1.4 Silyl-substituted heterocycles 30 1.4.1 Synthesis o f silylepoxides 30 1.4.2 Ring-opening reactions of silylepoxides 33 1.4.3 Synthesis and reactions of silylsubstituted aziridines 34 1.5 Synthesis of cyclic sulphates 35 1.6 Synthesis o f silyl-sultones 36 1.7 Scope of the thesis 36 1.8 Chapter one references 38 IV Chapter Two: Reactions of a-trialkylsilylvinyl carbanions with carbonyl Compounds. 2.1 Introduction 45 2.2 Results and discussion 52 2.2.1 Synthesis of trimethylsilylvinylmethylketene and ethyl- 2(trimethylsilyl) acrylate. 52 2.2.2 Reactions of the a-trimethylsilylvinyl carbanion with carboxylic acid derivatives. 54 2.2.2.1 Reaction of the a-trimethylsilylvinyl carbanion with anhydrides and acid-chlorides. 54 2.2.2.2 Reaction of the a-trialkylsilylvinyl carbanion with esters and carbamate derivatives 56 2.2.2.3 Reaction of the a-trialkylsilylvinyl carbanion with alkylchloro- formates 57 2.2.3 Reaction of the a-trialkylsilylvinyl carbanion with a,P-unsaturated carbonyl compounds 59 2.2 J. 1 Reaction of the a-trimethylsilylvinyl carbanion with an a,p-unsaturated ketones 59 2.2.3.2 Reaction of the a-trialkylsilylvinyl carbanion with an a,P-unsaturated ester 63 2.2.4 The effect of reaction conditions on the product distributiorL 66 2.2.5 Conclusion 66 2.3 Chapter Two References 68 Chapter Three: Synthesis of P-trialkylsilyl-substituted aziridines. 3.1 Introduction. ,7 0 3.2 Physical properties of aziridines. 70 3.3 Synthesis of aziridines 72 3.4 The chemistry of silylaziridines. 76 3.5. Some of the uses of aziridines. 82 3.6 Results and discussions 84 3.6.1 Synthesis of silyl-substituted aziridines from phenylazide by the thermolytic method 84 3.6.2 Synthesis of silyl-substituted aziridines from azidoformate by photolytic methods 90 3.6.3 Lithium aluminium hydride reduction of bromo azides. 94 3.6.4 Modification of silyl-substituted aziridines 97 3.6.4.1 Acylation of silyl-substituted aziridines 100 3.6.4 2 Ring expansion of silylaziridines. 101 3.7 Further studies on the ability of a silicon to stabilise a positive charge in the a - or P- position. 102 3.7.1. Introduction. 102 3.7.2. Results and discussion. 105 3.7.2.1 Synthesis of 2,3-bistrimethylsilylpropene: 105 3.7 2.2 Synthesis of trans 1,3-bistrimethylsilylpropene 106 3.7 2.3 Reaction of 2,3-bistrimethylsilylpropene with hydrogen chloride 107 3.7.2.4 Reaction of 1,3-bistrimethylsilylpropene with hydrogen chloride 112 3.8 hnproyed and novel synthesis of cyclic sulphates and sultones: A versatile route to aziridine synthesis 113 3.8.1 The chemistry of cyclic sulfates 113 3.8.2 Synthesis of cyclic sulfates 115 3.8.3 The synthesis of aziridine via cyclic sulphates 116 3.8.4 The chemistry of hypervalent organoiodine complex 119 vi 3.8.5 The chemistry of sultones 124 3.8.6 Results and discussions 132 3.8.6.1 Phenyliodosulfate. 132 3.8 6.2 Synthesis of sultones 134 3.8.6.3 Synthesis of cyclic sulfates via iodium ylids 140 3.9 Chapter three references 147 Chapter Four: Ring-opening reactions of P-triall^lsilylaziridines 4.1 Introduction 162 4.2 Ring opening reactions of non-silylaziiidines 163 4.3 Ring opening reactions of silyl epoxides 168 4.4 Ring opening reactions of a-trialkylsilyl aziridines 170 4:5 Results and discussion 172 4.5. i Ring-opening reactions of some simple P-trialkylsilyl aziridines 172 4.5.2 Formation of a Cait)6n-Halogen bond (C-X) in the product 177. 4.5.2.1 Ring-opening reactions of P-trialkylsilylaziridines with hydrogen halide(formation of C-Cl bond). 177 4.5.2.2 Reaction of silyl-aziridines with trimethylsilylhalides and pseudor halides. 182 4.5.3 Ring-opening reactions of g - trialkylsilylaziridines with nitrogen nucleophiles (formation of a C-N bond). 186 4.5.4 Ring-opening reactions of P-trialkylsilylaziridines with sulphur nucleophiles (formation o f a C-S bond). 188 4.5.5 Ring-opening reactions of p - trialkylsilylaziridines with oxygen nucleophiles (formation o f a C -0 bond) 190 4.5.6 Ring-opening reactions of P- trialkylsilylaziridines with reducing E^nts (formation of a C-H bond). 191 4.5.7 Ring-opening reactions of P-trialkylsilylaziridines by nucleophilic attack on silicon (Formation of allylamines) 193 vii 4.5.7.1 Fluorodesilylation of silylaziridines 197 4.5.7.2. Ring-openmg reactions with triflates 198 4.5.7.3 Ring opening reaction with trifluoroacetic acid 200 4.5.8 Reactions of P-trialkylsilylaziridines with carbon nucleophiles (formation o f a C - C bond) 201 4.6 Summary of the ring-opening reactions 203 4.7 Chrq^iter four references 206 Chapter Five: Experimental 5.1 Instruments and materials used 210 5.2 Preparation of starting materials. 212 5.2.1 Synthesis of vinyl-and allylsilanes 212 5.2.1.1 a-Bromovinyltrimethylsilane 212 5.2.1.2 3-Trimethylsilylbut-3-en-2-one 213 5.2.1.3 Methyl 2-(Trimethylsilyl)acrylate 215 5.2.1.4 Ethyl 2-(trimethylsilyl)acrylate 216 5.2.1.5 Synthesis of cis-allylsilanes 217 5.2.1.6 Synthesis of 2-bromo-3-trichlorosilylpropene 223 5.2.1.7 Synthesis of 2-bromo-3-trimethylsilylpropene 223 5.2.1.8 2,3-Bis(trimethylsilyl)propene 224 5.2.1.9 2-Carbomethoxy-3-trimethylsilylpropene 225 5.2.1.10 1 -Bromo-3-trimethylsilylpropene 227 5.2.1.11 1,3-Bistrimethylsilylpropene 228 5.3 Reactions ofa-lithiovinyhrimethylsilane with carbonyl compounds. 229 5.3.1 3,5-bis(trimethylsilyl)hexa-2,5-dien-2-yl acetate 229 5.3.2 3,5-bis(trimethylsilyl)hex-5-en-2-one 230 5.3.3 1 -Dimethylamido-1,3-bis(trimethylsilyl)but-3-ene 230 5.3.4 Triethyl 3rtrimethylsilylbut-3-ene-l,l,l-tricarboxylate 231 5.3.5 Trimethyl 3-trimethylsilylbut-3-ene-1,1,1 -tricarboxylate 232 vm 5.4 Reaction of a, p-unsaturated trimethylsilyl keto-enolates with carbonyl compounds. 233 5.4.1 Ethyl 2-oxO“3,5-bis(trimethylsilyl)hex-5-en-3-caiboxylate 233 5.4.2 Methyl 2-oxo-3,5-bis(trimethylsilyl)hex-5-en-3-caiboxylate 234 5.4.3 3-Ethylidene-5-trimethylsilyl-hex-5-ene-2-one 235 5.5 Reaction of a, p-unsaturated trimethylsilylester-enolates with caibonyl compounds.

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