Structure-Controlled Synthesis of Polyesteramides Utilizing Sugar Diols and Amino Acids

1.由氨基酸、糖二醇和脂肪族二元酸组成的聚酯酰胺的合成及生物降解性研究L-苯丙氨酸和L-丙氨酸与己二酸和癸二酸的缩合反应制备了一些二氨基二元酸。以二环己基碳二亚胺(DCC)为催化剂，将二氨基二元酸与1，4：3，6-二脱水-D-葡萄糖醇(DAG)或1，4：3，6-二脱水-D-甘露醇(DAM)缩聚，合成了聚酯酰胺。核磁共振谱和红外光谱分析表明，这些聚酯酰胺具有较好的结构。酶降解和土壤埋藏降解试验表明，聚酯酰胺的分子结构和生物降解性之间存在相关性。含有DAG或DAM单元的聚酯酰胺的降解性略低于含有脂肪族二醇单元的聚酯酰胺。侧链为羟基的聚酯酰胺的合成及其生物降解性。以L酒石酸为原料，经两步反应合成了2，3-O-异丙叉基-L-苏糖醇。将上述二氨基二元酸与受保护的L-苏糖醇在二氯甲烷存在下缩合，得到相应的聚酯酰胺。用三氟乙酸处理异丙叉保护基，得到以游离羟基为侧链的聚酯酰胺。羟基的引入显著加速了聚酯酰胺的生物降解。我们的研究开辟了一条利用氨基酸和糖二醇等可再生自然资源合成结构明确的可生物降解聚酯酰胺的方法。

1. Synthesis and biodegradability of polyesteramides consisting of amino acid, sugar diol, and aliphatic dicarboxylic acid unitsSome diamidodicarboxylic acids were prepared by condensations of combinations of L-phenylalanine and L-alanine with adipic acid and sebacic acid. Polyesteramides were synthesized by polycondensation of the diamidodicarboxylic acids with 1,4:3,6-dianhydro-D-glucitol (DAG) or 1,4:3,6-dianhydro-D-mannitol(DAM) in the presence of dicyclohexylcarbodiimide (DCC). NMR and IR analysis indicated that these polyesteramides were composed of well-defined structure. Enzymatic degradation and soil burial degradation tests suggested a correlation between the molecular structure and biodegradability of the polyesteramides. Those containing DAG or DAM units showed a somewhat lower degradability than that of polyesteramides containing aliphatic diol units.2. Synthesis and biodegradability of polyesteramides with hydroxyl groups as side chains.2,3-O-isopropyliden-L-threitol was prepared from L-tartaric acid via two-step reactions. The diamidodicarboxylic acid described above were polycondensed with the protected L-threitol in the presence of DCC to yield the corresponding polyesteramides. The isopropylidene protecting groups were removed by the treatment with trifluoroacetic acid to give polyesteramides having free hydroxyl groups as side chains. The introduction of hydroxyl groups significantly accelerated the biodegradation of the polyesteramides.Our research opened a promising way to synthesize structurally well-defined biodegradable polyesteramides utilizing renewable natural resources such as amino acids and sugar diols.