Synthesis of γ-Glutamyl Peptides

Abstract

IN the classical synthesis by Bergmann and Zervas¹, carbobenzoxy L-glutamic anhydride reacts with amino-acid esters to yield, after saponification and hydrogenation, α-glutamyl peptides. There have, however, been indications that the anhydride ring may not open exclusively in this direction. Bergmann² reported that glycylglycine ethyl ester yields a mixture of the α- and γ-derivatives, and in the analogous reaction with ammonia Melville³ found some 14 per cent glutamine admixed with the isoglutamine. Anomalies have also been observed in the opening of the ring of carbobenzoxy L-aspartic anhydride⁴.