Studies on condensed-heterocyclic azolium cephalosporins. III. Synthesis and antibacterial activity of 7 beta-[2-(2-amino-5-substituted-thiazol-4-yl)-2 (Z)-alkoxyiminoacetamido]-3-(condensed-heterocyclic azolium)methyl-3-cephem-4- carboxylates.

As a part of our research on the synthesis of cephalosporins bearing condensed-heterocyclic azolium groups at the 3 position in the cephalosporin nucleus, we describe herein the synthesis of 7β-[2-(2-amino-5-halogeno-, methylthio-, methylsulfinyl-, methylsulfonyl- and sulfothiazol-4-yl)-2(Z)-alkoxyiminoacetamido]cephalosporins and their antibacterial activity. Among the compounds prepared, 7β-[2-(2-amino-5-chlorothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3-(imidazo[1, 5-a]-pyridinium-1-yl)methyl-3-cephem-4-carboxylate (14) showed good antibacterial activity against both Staphylococcus aureus including methicillin-resistant Staphylococcus aureus (MRS A) and Pseudomonas aeruginosa, whereas the antibacterial activity against other Gram-negative bacteria was a slightly lower than that of 7β-[2-(2-aminothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3-(imidazo[1, 2-a]pyridinium (I-1) and imidazo[1, 5-a]pyridinium (I-4)-1-yl)methyl-3-cephem-4-carboxylates.