Studies on the enantioselective synthesis of α-amino acids via asymmetric phase-transfer catalysis

In this paper, we describe investigations into the use of cinchona alkaloid-derived quaternary ammonium phase-transfer catalysts for the asymmetric alkylation of a benzophenone-derived glycine-imine. Utility of this process is demonstrated by the enantioselective synthesis of a range of α-amino acid esters.