N-HYDROXY AMIDES .1. SYNTHESIS OF N-BENZYLOXY AND N-HYDROXY PEPTIDES VIA POLYMERIZATION OF N-BENZYLOXY DL-ALPHA-AMINO ACID N-CARBOXY ANHYDRIDES

Polymerization of N-benzyloxy DL- alpha -amino acid N-carboxy anhydrides (N-benzyloxy-NCAs) has been carried out in benzene for 30 d with cyclohexylamine as initiator. The N-benzyloxy-NCAs of glycine, alanine, 2-aminobutyric acid, and leucine give the corresponding polymers in good yields, while the starting material is recovered from those of valine and phenylalanine. The different behavior in the polymerization is discussed in terms of steric crowding. Catalytic hydrogenation of the N-benzyloxy polymers produces poly(N-hydroxy peptide)s. Complex formation of these polymers with iron(III) has been examined. Among the polymers, poly(N-hydroxyalanine) is further converted into poly(N-acetoxyalanine), which acts as an acyl active polymer.