Studies on semisynthesis and antibacterial activity of 3-heterocyclicthiomethyl cephalosporins

Fourteen new mother nucleus of 7-amino-3-heterocyclicthiomethyl cephalospor ins 2a-2n were synthesized by the reaction of 7-ACA with 2-substituted 1,3, 4-oxadiazol-5-thione la-lg, 2-arylamino-1,3,4-thiadiazol-5-thione 1h-1l or 1, 2, 4-triazoline-5-thione 1m In. Two new compounds, 7- (1-aryl-5-methyl-1 H-1,2, 3-triazol-4-formylamido)-3-(2-substituted 1,3, 4-oxadiazol-5-thiomet hyl) cephalosporins 4c, 4d , were obtained by the acylation of 7-amino grou p of 2c , 2d with 1-aryl-5-methyl-1H-1,2,3-triazol-4-formyl chloride 3a, 3b , The structures of the compounds synthesized were confirmed by elementary analyses, IR, H-1 NMR and FAB-MS, In preliminary antibacterial sensitivity test, the compounds 2a-21 were found to show higher antibacterial activity than 7-ACA against Gram-positive bacteria, 4c, 4d were found to have signif icant antibacterial activity against both Gram-positive and Gram-negative b acteria.