| abstract |
β-lactam antibiotics of formula (I) or a salt thereof, wherein R 1 is hydrogen, methoxy of formamido; R 2 is an acyl group, in particular that of an antibacterially active cephalosporin; CO 2 R 3 is a carboxy group or a carboxylate anion, or R 3 is a readily removable carboxy protecting group (such as a pharmaceutically acceptable in vivo hydrolysable ester group); R 4 represents up to four substituents selected from alkyl, alkenyl, alkynyl, alkoxy, hydroxy, halogen, amino, alkylamino, acylamino, dialkylamino, CO 2 R, CONR 2 , SO 2 NR 2 (where R is hydrogen or C 1-6 alkyl), aryl and heterocyclyl, which may be the same or different and wherein any R 4 alkyl substituent is optionally substituted by any other R 4 substituent; X is S, SO, SO 2 , O or CH 2 ; Y is S, SO or SO 2 ; and m is 1 or 2, useful in the treatment of bacterial infections in humans and animals. ##STR1## |