7-Acylamido-3-cephem-4-carboxylic acid antibiotics directly substituted in the 3-position of the cephem ring system with a sulfur atom bonded to a 5- or 6-membered heterocyclic ring, a lower alkyl group, or a phenyl or substituted phenyl group are prepared with the corresponding 3-halo-3-cephem esters. For example, p-nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-chloro-3-cephem-4-carboxylate reacts with 1-methyl-1H-tetrazol-5-ylthiol to provide p-nitrobenzyl 7-[2-(2-thienyl)acetamido]-3-[(1-methyl-1H-tetrazol-5-yl)thio]-3-cephem-4- carboxylate. The p-nitrobenzyl ester group is removed by catalytic hydrogenolysis to provide the antibiotic carboxylic acid compound. Alternatively, the antibiotics are prepared by reacting a 3-alkylsulfonyloxy, or 3-arylsulfonyloxy-3-cephem, for example, 3-methanesulfonyloxy-3-cephem, or a 3-p-toluenesulfonyloxy-3-cephem with the heterocyclic thiol, the phenyl or substituted phenylthiol, or with the lower alkylthiol.
7-酰胺基-3-头孢烯-4-
羧酸类抗生素直接取代头孢環系統的3位,
硫原子與5-或6-成員的杂环环,低烷基基团或苯基或取代苯基结合,是通过相应的3-卤代-3-头孢酯制备的。例如,对硝基苄基7-[2-(2-
噻吩基)乙酰胺基]-3-
氯-3-头孢烯-4-
羧酸酯与
1-甲基-1H-四唑-5-基
硫醇反应,提供对硝基苄基7-[2-(2-
噻吩基)乙酰胺基]-3-[(
1-甲基-1H-四唑-5-基)
硫基]-3-头孢烯-4-
羧酸酯。对硝基苄基酯基团经催化氢解去除,提供抗生素
羧酸化合物。另外,抗生素可通过将3-烷基磺酰氧基或3-芳基磺酰氧基-3-头孢烯,例如,3-
甲烷磺酰氧基-3-头孢烯,或3-对
甲苯磺酰氧基-3-头孢烯与杂环
硫醇,苯基或取代苯基
硫醇,或与低烷基
硫醇反应来制备。