α‐Chiral Acetylenes Having an All‐Carbon Quaternary Center: Phase Transfer Catalyzed Enantioselective α Alkylation of α‐Alkyl‐α‐alkynyl Esters

Abstract

Going through the phases: The title reaction was found to proceed by an initial base-mediated isomerization to allenyl esters and subsequent phase transfer catalyzed alkylation at the alpha position of the ester (see scheme).