Asymmetric synthesis of gamma-D-and -L-glutamyl-L-meso-diaminopimelic acid dipeptide

A new synthetic method for peptide coupling involves a regioselective ring-opening of the differentially N-protected bis-lactone form of meso-diaminopimelic acid. This technique facilitates the synthesis of gamma-D- and gamma-L-glutamyl-L-meso-diaminopimelic acid dipeptides. Diphenyloxazinones with N-t-BOC and N-CBz protecting groups help prepare the N-protected form of meso-diaminopimelic acid.