Glen R. Buell

Silicon-29 NMR: Unusual chemical shift trends in the substituted phenyltrifluorosilane system

Abstract The response of the silicon-29 NMR resonance to substitution on phenyl in a series of phenyltrifluorosilanes was opposite to that reported for the corresponding phenyltrimethylsilanes.

Tetracyclohexylsilane: The resolution of an enigma

Abstract The conflicting experimental data and subsequent rationalizations in the literature on tetracyclohexylsilane are critically examined. It is established that the authentic compound, obtained by hydrogenation of tetraphenylsilane, can be synthesized by organolithium condensation, although a prior report mistakenly identified an impurity-caused product, tricyclohexyl(cyclohexyloxy)silane, as such. Studies on cyclohexyllithium and cyclopentylmethyllithium, as well as the synthesis of tricyclohexyl(cyclopentylmethyl)silane and its aromatic analog, demonstrate that the literature on the subject can be resolved without invoking isomerism due to rearrangement, restricted rotation, frozen conformation, or polymorphism.

Optically active silanes and their reactions: the perhydromethyl-1-naphthylphenylsilyl system

The first reported aliphatic silyl system optically active at silicon has been prepared by the catalytic hydrogenation of the methyl-1-naphthylphenylsilyl system, (R3Si*−). Both the menthoxy and the fluoro derivative of R3Si*− have been found to proceed smoothly to the perhydro derivative (RH3Si*−). Isomers were observed due to the four possible cis/trans configurations of the perhydro-1-naphthyl group. Reactions of the RH3Si*− assemblage were found, in general, to be stereospecific and to conform to the rules of stereospecific reactions at silicon as proposed by Sommer. A significant exception to the high degree of stereoselectivity generally exhibited by the RH3Si*-system was the hydrolysis of RH3Si*Cl to form the silanol. In a seriesof runs the resulting silanol was found to vary from 0 to 21% in optical purity.