PART ONE: SELECTIVE REDISTRIBUTION REACTIONS OF ORGANOSILANES IN THE PRESENCE OF CHLOROPLATINIC ACID. PART TWO: STERIC EFFECTS IN THE SILYLATION OF ESTER ENOLATES AND THE REARRANGEMENT OF O-SILYLKETENE ACETALS INTO ALPHA-SILYL ESTERS.
Abstract
Part One. Tetraalkylsilanes undergo redistribution reactions quite selectively in the presence of trichlorosilane and chloroplatinic acid. It is the smallest of the alkyl groups on the tetraalkylsilane which exchange most readily with a chloro group on trichlorosilane. Two possible mechanisms for the redistribution reactions are proposed. The selectivity is attributed to the steric hindrance of the alkyl groups on the tetraalkylsilane. Part Two. Steric effects in the silylation of lithium ester enolates were assessed. Steric hindrance in the acid portion of an ester favored oxygen silylation. Under certain conditions, bis-silylated products were formed wherein a trimethylsilyl group was bonded to both carbon and oxygen. The rearrangement of O-silylketene acetals to their C-silyl analogs by the use of group IIB metal iodides as catalysts has also been studied. It was found that the combination of a group IIB metal iodide and molecular iodine accelerates the rearrangement reaction most effectively. A tentative mechanism is proposed to accommodate the rearrangements with group IIB metal iodides as catalysts. The catalytic function of molecular iodine in these rearrangements is also discussed.
Degree
Ph.D.
Subject Area
Organic chemistry
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