Sulfone reagents in organic synthesis: VI. Sulfonyl- and silyl-substituted hydrocarbons as versatile carbanion precursors in organic synthesis

Abstract

The basic organometallic chemistry of β-silyl-substituted acetylenic, vinylic and alkyl sulfones has been investigated, with attention being given to metallation, carbometallation and the chemical reduction of carbon—carbon unsaturation. 2-Trimethylsilylvinyl and 2-trimethylsilylalkyl sulfones underwent smooth and stereoselective lithiation with RLi on the carbon α to the sulfonyl group. Carbometallation of vinyl sulfones could be achieved with RMgX or LiCuR 2, but acetylenic sulfones carbometallated smoothly only with LiCuR 2; with RMgX or RLi, these acetylenes underwent alkyldesulfonylation. The utility in synthesis of these metallo derivatives of sulfonyl-silyl-hydrocarbons is discussed and their value in elaborating carbon skeletons is illustrated for the preparation of alkenes, allenes, carbocycles and stereo-defined vinyl sulfones.