Asymmetric synthesis of γ-lactones through reaction of sulfoxonium ylides, aldehydes, and ketenes

A method for the enantioselective synthesis of γ-lactones through the reaction of enantioenriched sulfoxonium ylides, aldehydes, and ketenes was developed. Enantioenriched (98% ee) aminosulfoxonium ylide was subjected to reaction with a variety of aldehydes (both aromatic and aliphatic) and disubstituted ketenes, leading to the formation of α,β-substituted γ-lactones in moderate to very good diastereoselectivity (dr up to 95:5) and with enantiomeric excesses of up to 79% ee. Best levels of enantioselectivity were observed in the reactions of enantioenriched aminosulfoxonium ylide with isobutyraldehyde and various alkylarylketenes.