Thermal rearrangements of reactive intermediates in organosilicon chemistry
Date
Authors
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Research Projects
Organizational Units
Journal Issue
Is Version Of
Versions
Series
Department
Abstract
It is well known that silicon undergoes facile 1,5-migrations from carbon to carbon. In an attempt to generate a (p-p) (pi) bonded silicon via a 1,5-trimethylsilyl migration from silicon to oxygen, it was found that cis-7,7,8,8-tetramethyl-7,8-disilanon-5-en-4-one did not rearrange thermally or photochemically to a silene. Rather, coordination of the internal silicon with oxygen followed by 1,2-silicon migration afforded a cyclic silylenol ether;The thermolysis of 1,2-diallyl, 1,2-dibenzyl and 1-allyl-1-benzyldisilanes affords silicon centered radicals. These radicals were found to cyclize by (pi)-addition followed by rearrangement or by ipso substitution. This discovery prompted the proposal of a mechanistic alternative to the thermal conversion of allyltrimethylsilane to trimethylvinylsilane. A deuterium labeling study provides support for the proposed mechanism;An unprecedented silene to silylene rearrangement was discovered. The thermal decomposition of allyl, benzyl and polysilanes generates silicon radicals which disproportionate to silylsilenes, then rearrange to silylenes by a 1,2-silicon migration and ultimately form 1,3-disilacyclobutanes by C-H insertion. This silene to silylene rearrangement was unambiguously shown to occur when (trimethylsilyl)methylsilene was generated by a retro Diels-Alder reaction. The successful incorporation of this rearrangement into a novel system furnished an unprecedented silylene to silene to silylene arrangement;A new reaction of silylenes and acetylene was discovered. Copyrolysis of 2-methoxyheptamethyltrisilane and acetylene affords trans-(beta)-(trimethylsilylvinyl)methylethynylsilane. A mechanism involving rearrangement of 1-trimethylsilyl-1-methyl-1-silacycloprop-2-ene to trans-(beta)-(trimethylsilylvinyl)methylsilylene is proposed.