Isocyanocephalosporanates

Claim 1

A compound of formula: ##SPC4## wherein the dotted line represents a double bond at either position 2- or 3-, n is zero of 1, X is a carboxylic acid group, a non-toxic salt thereof, or an esterified carboxylic acid group wherein the ester portion is selected from the group consisting of benzyl, para-methoxybenzyl, 2,2,2-trichloroethyl, tertbutyl, acetoxymethyl, pivaloyloxymethyl, phthalidyl and a lactone of the formula ##EQU6## wherein Z 1 is 1,2-phenylene or 4,5-dimethoxyphenyl-1,2-ene, R is hydrogen, an acetoxy group, a pyridinium group or a group of the formula -SR 2 , wherein R 2 represents a 5- or 6-membered heterocyclic ring containing one to four nitrogen heteroatoms, one oxygen heteroatom and one to three nitrogen heteroatoms or one sulphur heteroatom and one to three nitrogen heteroatoms, unsubstituted or substituted with one or two groups selected from alkyl, cycloalkyl, or alkenyl, each having up to four carbon atoms, alkoxy or alkoxyalkyl, each alkyl or alkoxy having one to four carbon atoms, CF 3 , NHR 3 , NR 2 3 , SCH 2 , halogen, amino, phenyl and benzyl wherein R 3 is alkyl of 1 to 4 carbon atoms; or X and R taken together represent the divalent radical ##EQU7## and R 1 is hydroxyloweralkyl, lowerakloxycarbonylloweralkyl, benzyloxycarbonylloweralkyl, benzyl or loweralkylthio.