Polymerization of N-benzyloxy Dl-α-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. Treatment of poly(N-benzyloxyalanine) with B(CF3CO2)3 gives 1,4-dihydroxy-3,6-dimethyl-2,5-piperazinedione.
以
环己胺为
引发剂,N-苄氧基 Dl-
α-氨基酸 N-
羧酸酐(N-苄氧基-NCAs)在苯中聚合 30 d。甘
氨酸、丙
氨酸、2-
氨基
丁酸和亮
氨酸的 N-苄氧基-NCAs 能以良好的收率生成相应的聚合物,而缬
氨酸和苯丙
氨酸的 N-苄氧基-NCAs 则能回收起始原料。聚合过程中的不同行为将从立体拥挤的角度进行讨论。对 N-苄氧基聚合物进行催化氢化可生成聚(N-羟基肽)。研究了这些聚合物与
铁(III)形成的络合物。在这些聚合物中,聚(N-羟基丙
氨酸)可进一步转化为聚(N-乙酰氧基丙
氨酸),后者是一种酰基活性聚合物。用 B(CF3CO2)3 处理聚(N-苄氧基丙
氨酸)可得到 1,4-二羟基-
3,6-二甲基-2,5-哌嗪二酮。