Enantioselective synthesis of α-hydroxy γ-butyrolactones from an ephedrine-derived morpholine-dione

An ephedrine-derived morpholine dione is employed in the enantioselective synthesis of (S)-α-hydroxy γ,γ-dimethyl-γ-butyrolactone and (S)-α-hydroxy γ-butyrolactone. A one-pot alkylation/allylation protocol for the stereoselective conversion of the dione to 2-alkyl-2-allyl morpholinones, key intermediates for α-alkyl-α-hydroxy-γ-butyrolactones, is described.