An approach to broad-spectrum cephalosporins

Based on our view that cephalosporins with potent activities share active hydrogen(s) on the alpha-carbon of the side chain acyl, we undertook to introduce beta-ketoacid moieties onto the cephalosporin structure. Thus, starting with deacetylcephalosporin C (DCPC), first made available in quantities by our own fermentation technique, 7-amino-3'-O-acetoacetyldeacetylcephalosporanic acid (7-AACA) was made accesible. Acylation of 7-AACA with various beta-ketoacids followed by substitution at the 3'-position led to 7 beta-[2-(2-aminothiazol-4-yl)acetamido]-3-[[1-(2-dimethylaminoethyl)-1H-tetrazol-5-yl]thiomethyl]ceph-3-em-4-carboxylic acid (SCE-963, cefotiam), a potent broad-spectrum cephalosporin. Further elaboration of the structure of cefotiam led to an extended broad-spectrum cephalosporin, SCE-1365. These two classes of cephalosporins, together with our previously reported antipseudomonal cephalosporin (SCE-129, cefsulodin), could control a wide range of pathogenic bacteria.