Diastereoselectivity in the alkylation of enolates having an adjacent silkyl group

Abstract

The methylation of open-chain enolates having an adjacent silyl group is highly diastereoselective in favour of the isomer (2) having the silyl and methyl groups trans on the carbon chain; protonation of the corresponding enolate, already carrying the methyl group, gives the other diastereoisomer (3), but with somewhat lower diastereoselectivity.