| abstract |
A monocyclic β-lactam antibiotic having a formamido substituent at the 3S-position, including compounds of the formula (I): ##STR1## and salts thereof wherein R is --SO 3 H; --PO(OH)Y wherein Y is C 1-6 alkoxy, hydroxy, aryloxy, C 1-6 alkyl or aryl; ##STR2## wherein Z represents C 1-6 alkyl or aryl; ##STR3## wherein Z 1 and Z 2 may be the same or different and each represents hydrogen, C 1-6 alkyl, aryl, amino or C 1-6 alkoxy, or Z 1 and Z 2 together form the residue of a heterocyclic ring; --OSO 3 H; or ##STR4## where X is hydrogen or hydroxy; R 1 is an amino, protected amino or carboxylic acylamino group, and R 2 and R 3 are independently selected from hydrogen or a hydrocarbon group of 1 to 18 carbon atoms. |