7β-[2-Etherified oximino-2-(thienyl-,furyl- or pyridylacetamido)]cephalosporins

Claim 1

A compound selected from the group consisting of a highly active cephalosporin antibiotic highly stable to β-lactamases, having the formula ##STR152## wherein R u is thienyl, furyl or pyridyl or any of these groups substituted by chloro, bromo, iodo, fluoro, hydroxy, lower alkyl, nitro, amino, loweralkylamino, diloweralkylamino, lower alkanoyl, lower alkanoylamino, lower alkoxy, lower alkylthio or carbamoyl; R b is phenyl; naphthyl; benzyl; phenylethyl; diphenylmethyl; triphenylmethyl; thienylmethyl; furylmethyl; pyridylmethyl; pyrrolylmethyl or any of these groups substituted by hydroxy, lower alkoxy, phenoxy, benzyloxy, carboxy, lower alkoxycarbonyl, benzyloxycarbonyl, mercapto, lower alkylthio, phenylthio, benzylthio, acetamido, benzamido, cyano, formyl, lower alkanoyl, benzoyl, amino, methylamino, ethylamino, dimethylamino, lower alkoxycarbonylamino, benzyloxycarbonylamino, phthalimido, acetoxy, propionyloxy, pivaloyloxy, chloro, bromo, iodo, fluoro, nitro or azido; and Y is a group of formula --O.CO.R 9 where R 9 is an alkyl or alkenyl group containing up to 4 carbon atoms or phenyl, said cephalosporin antibiotic being in the form of a syn isomer free of the corresponding anti isomer to the extent of at least 75% based on the total weight of said antibiotic; and a physiologically acceptable salt thereof.