Highly enantioselective synthesis of cyclic and functionalized α-amino acids by means of a chiral phase transfer catalyst

The chiral quaternary ammonium salt 1 serves as phase transfer catalyst for the enantioselective conversion of the glycine derivative 2 to a variety of cyclic and acyclic chiral α-amino acids with enantioselectivities as high as 200:1 in alkylation and Michael addition reactions.