An umpolung sulfoxide reagent as α-hydroxy and α-chloro benzyl carbanion equivalents

ortho-[(N-Methyl)carbamoyl]phenyl benzyl sulfoxide is used as a synthetic equivalent of α-hydroxy and α-chloro benzyl carbanions by means of a two-step sequence involving (1) highly stereoselective α-C-alkylation with alkyl bromides, and (2) displacement of the sulfinyl group by an OH or a Cl under Pummerer or chloro-Pummerer conditions, respectively. The sulfinyl auxiliary can be effectively regenerated and recycled.