Synthesis of Polypeptide Having Defined Terminal Structures Through Polymerization of Activated Urethane-Derivative of γ-Benzyl-l-glutamate

A new synthetic method of polypeptide having defined terminal structures was established with using an acyclic urethane of α-amino acid as a monomer. The urethane derivative presented herein is N -(4-nitrophenoxycarbonyl)-γ-benzyl- l -glutamate, of which polymerization behavior in N, N -dimethylacetamide (DMAc) in the presence of various amines was examined. The polymerization was accelerated remarkably by adding butylamine so that it proceeded smoothly at 30 °C to afford the corresponding polycondensate, poly(γ-benzyl- l -glutamate) (poly(BLG)). Detailed structural analysis of the obtained poly(BLG) with MALDI−TOF mass spectrometry revealed that butylamine was incorporated into the terminal of poly(BLG) and the other terminal was endowed with amino group.