Date of Award
Doctor of Philosophy
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.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Stephanie Ann Burns
Burns, Stephanie Ann, "Thermal rearrangements of reactive intermediates in organosilicon chemistry " (1982). Retrospective Theses and Dissertations. 7494.