头孢母核7-ACCA的合成与表征

7-氨基-3-氯-3-头孢烯-4-酸（7-ACCA）是合成多种头孢菌素的重要中间体。文中以3-氯代头孢二苯甲酯为起始物，经弱酸苯酚水解去4位二苯甲基和固定化青霉酶PGA-450 裂解去7位苯乙酰基两步反应制得7-ACCA，两步总收率达85.0%以上。用HPLC测定其含量,产品7-ACCA质量分数达99.0%以上，略高于所购进标品。用红外、元素分析和核磁共振对7-ACC A进行了结构表征，结果表明，样品7-ACCA的分析结果与标准样品7-ACCA的结果一致。试验发现，去4位二苯甲基最佳反应温度为60～65℃，去7位苯乙酰基的最佳温度为30～32℃，最佳pH值为9.0。在最佳反应条件下，进行了400～450批的批次实验，转化率和收率都无明显降低。本合成方法工艺简洁、产率高，所用试剂价廉易得，基本无污染。

Synthesis and characterization of cephalosporin nucleus 7-ACCA

7-amino-3-chloro-cephems-3-en-4-acid(7-ACCA) is an important intermedia te in preparation of cephalosporin. The process for preparating 7-ACCA using 3-chloro-cephalosporin as a raw material via two reactions of hydrolyzation and enzyme cleavage was described. The total yield was up to 85.0%. The product was assayed by HPLC, and the content was up to 99%, greater than that of the standard 7-ACCA. The product was also characterized by IR, element analysis, and NMR, and the results of the sample 7-ACCA was consistent with that of the standard 7-ACCA. It is found that the optimum temperature of hydrolyzation reaction is 60～65℃, the optimum temperature of enzyme cleavage reaction is 30～32℃ and the optimum pH is 9.0. Under the best reactive conditions, a batch experiment was carried out for 400～500 times, and the yield did not reduce evidently. The preparation procedure is efficient, the yield is high, the reagents used are che ap, and convenient to get with low pollution, and it is very easy to be industrialized.