| abstract |
New 1-oxa-dethia-cephalosporins are of formula (I) (where Ar is 2- or 3-thienyl phenyl, p-hydroxyphenyl or p-acyloxyphenyl; COB, and COB2 are COOH or protected carboxy; Het is u-methyltetrazol-5-yl (MT), opt. protected 1-carboxymethyltetrazol-5-yl (CMT) or 2-methyl-1, 3, 4-thiadiazol-5-yl (MTD); Y is H or MeO; with the provido that Het must be MT when Y is MeO). (I) have 4-8 times the antibacterial activity of the corresp. true cephalosporins, esp. against Gram. neg. bacteria (including resistant Pseudomonas strains), and have better stability than known 1-oxa-dethiacephalosporins. A typical cpd. is diphenylmethyl 7 beta-(beta-phenyl-alpha-diphenylmethoxycarbonylacetamido)-3-(-1-t- hiomethyl)-1-oxadethia-3-cephem-4-carboxylate. In an example, this is prepd. by reacting the corresp. 7-amino cpd. with monodiphenylmethyl phenylmalonate. |