Asymmetric Synthesis of α‐Acyl‐γ‐butyrolactones Possessing All‐Carbon Quaternary Stereocenters by Phase‐Transfer‐Catalyzed Alkylation

The enantioselective construction of all‐carbon quaternary stereocenters on α‐acyl‐γ‐butyrolactones has been achieved by the N‐spiro chiral quaternary ammonium bromide 1‐catalyzed alkylation under mild phase‐transfer conditions. The resulting α‐alkylated keto lactones serve as valuable chiral building blocks in organic synthesis as clearly demonstrated by the facile conversion to optically active α,α‐dialkyl‐α‐amino acid derivatives via Schmidt rearrangement.