A NEW APPROACH TO THE SYNTHESIS OF DIPEPTIDES WITH UNNATURAL AMINO-ACIDS USING ORGANOZINC CHEMISTRY

Dipeptides which incorporate an iodoalanine unit at either the N- or C-terminus can be converted into the corresponding organozinc reagents upon treatment with activated zinc. The C-terminal dipeptide organozinc reagents undergo palladium-catalysed reaction with electrophiles to give dipeptides incorporating non-proteinogenic amino acids without loss of stereochemical purity. The N-terminal organozinc reagents are less synthetically useful.