Penam derivatives and salts thereof, processes for producing the same and antibacterial agent comprising the same

Abstract From the Canadian patent

A penam derivative represented by the, following general formula or a salt thereof: (see fig. I), wherein R1 represents a hydrogen atom an, amino-protecting group or an acyl group; R2 represents a hydrogen atom or a lower alkyl group; R3 represents a hydrogen atom, a lower alkoxy group, a lower alkylthio group or a formamido group; R4 represents a protected or unprotected carboxyl group or a carboxylato group; R represents a group of the formula, -NHR5 or -NR5R6 (in which R5 and R6, 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 …