Penam derivatives and salts thereof, and antibacterial agent comprising

Abstract

A penam derivative represented by the following general formula or a salt thereof: ##STR1## wherein R.sup.1 represents a hydrogen atom, an amino-protecting group or an acyl group; R.sup.2 represents a hydrogen atom or a lower alkyl group; R.sup.3 represents a hydrogen atom, a lower alkoxy group, a lower alkylthio group or a formamido group; R.sup.4 represents a protected or unprotected carboxy group or a craboxylato group; R represents a group of the formula, --NHR.sup.5 or --NR.sup.5 R.sup.6 (in which R.sup.5 and R.sup.6, which may be the same or different, represent protected or unprotected hydroxyl groups, cyano groups, sulfo groups, or unsubstituted or substituted lower alkyl, aryl, acyl, carbamoyl, sulfamoyl, lower alkylsulfonyl or heterocyclic groups) or a group of the formula, --N.dbd.CR.sup.7 R.sup.8 (in which R.sup.7 and R.sup.8, which may be the same or different, represent hydrogen atoms or protected or unprotected carboxyl groups, cyano groups or unsubstituted or substituted lower alkyl, lower alkenyl, lower alkynyl, aryl, amino, acyl, acyloxy, carbamoyl, carbamoyloxy, sulfamoyl, lower alkylthio, ureido or heterocyclic groups, or R.sup.7 and R.sup.8 may form a cycloalkene or a heterocyclic ring with the carbon atom to which R.sup.7 and R.sup.8 are attached); and n represents 1 or 2. The above penam derivative or its salt is very effective as antibacterial agents.