Chiral α-Substituted Carbonyls and Alcohols from the SN2‘ Displacement of Cuprates on Chiral Carbonates: An Alternative to the Alkylation of Chiral Enolates

A highly stereoselective sequence of reactions, based on the anti-selective S(N)2' addition of cuprates to allylic carbonates, transforms alkynes or alkenyl halides into carbonyls having alpha-chiral centers. The method, which uses menthone as a chiral auxiliary, is a useful alternative to the alkylation of chiral enolates with the added advantage of allowing for the "alkylation" of sec- and tert-alkyl and aryl groups.