HOMOLOGATION OF L-PHENYLALANINE TO KETOMETHYLENE AND HYDROXYETHYLENE DIPEPTIDE ISOSTERES VIA 2-THIAZOLYL AMINO KETONE INTERMEDIATE

A highly efficient route is presented for the synthesis of N-protected isosteric dipeptides Pheψ[COCH 2 ]Gly and Pheψ[CH(OH)CH 2 ]Phe from L -phenylalanine through 2-thiazolyl α-amino ketone and δ-amino-γ-hydroxy-(E)-α,β-enoate derivatives as key intermediates.