3-[(1,2,3-Thiadiazol-5-ylthio)methyl]cephalosporins.

The syntheses of ten 3-](1,2,3-thiadiazol-5-ylthio)methyl]cephalosporins, made by displacement of the 3'-acetoxy group by the novel thiol derivatives, potassium 1,2,3-thiadiazole-5-thiolate and dipotassium 1,2,3-thiadiazole-4-carboxylate-5-thiolate, are described. Several of the compounds showed good in vitro antibacterial activity against both Gram-positive and Gram-negative organisms. The subcutaneous in vivo activities against Staphylococcus aureus were generally less than that of cafazolin. Four of the compounds were administered orally and all were active; the 7 beta-(thiophen-2-acetamido) and 7 beta-(D-2-amino-2-phenylacetamido)-3-[(1,2,3-thiadiazol-5-ylthio)methyl] compounds were equally active by either route, with a PD50 of ca. 1 mg/kg.