Process for their preparation of .beta.-lactam antibacterial agents

Abstract

A process for the preparation of the compounds of the formula (II): ##STR1## and salts and cleavable esters thereof wherein R.sub.1 is a hydrocarbon group of up to 12 carbon atoms and which optionally also contain up to 4 heteratoms selected from oxygen, nitrogen, sulphur or chlorine and bromine which process comprises the reaction of a cleavable ester of a compound of the formula (III): ##STR2## with one equivalent of a strong base of low nucleophilicity and thereafter with a compound of the formula (IV) or (V): R.sup.2 SO.sub.2 SR.sub.1.sup.1 (IV) Cl--S--R.sub.1.sup.1 (V) wherein R.sub.1.sup.1 is a group R.sub.1 in which any amino substituent is protected and R.sup.2 is an alkyl group of 1-4 carbon atoms optionally substituted by a phenyl group or is a phenyl group optionally substituted by an alkyl group of 1-4 carbon atoms and thereafter if desired cleaving the ester moiety to yield the acid of the formula (II) or a salt thereof and removing the protecting group from any protected amino group present in R.sub.1.sup.1 ; is described.

Dependencies are inferred from the claim text.