Reactions of the α-carbanion species of (phenylthio)acetic acid and its ester with carbonyl compounds

Reactions of the (phenylthio)acetic acid dianion (2) and its ester monoanion (3) with carbonyl compounds are described. Both the carbanions (2) and (3) react well with saturated aldehydes and ketones to give the α-(1-hydroxyalkyl) substituted derivatives in excellent yields. In the reaction with conjugated enones, the dianion (2) undergoes exclusive 1,2-addition, while the monoanion (3) gives 1,4-addition. Reaction of the dianion (2) with saturated esters produces directly phenylthiomethyl ketones through decarboxylation of the intermediates, whereas the reaction with αβ-unsaturated esters was found to be unsatisfactory. On the other hand, unlike the reaction with saturated esters, the reaction of the monoanion (3) with αβ-unsaturated esters proceeds well to yield 1,4-addition products.