Patent ID: 7687488

Claim:
2-Substituted methyl penam compounds of the formula (I), their tautomeric forms, their stereoisomers, and their pharmaceutically acceptable salts, wherein: A=C or N; Het is a five- to six-membered heterocyclic ring; R 1 represents carboxylate anion, or —COOR 4 wherein R 4 represents hydrogen, carboxylic acid protecting group or a pharmaceutically acceptable salt; R 2 and R 3 may be same or different and independently represent hydrogen, halogen, amino, protected amino, optionally substituted alkyl, alkenyl, alkynyl; and R is represented by substituted or unsubstituted alkyl, alkenyl, aryl, aralkyl, cycloalkyl, oxo, heterocyclyl or heterocyclylalkyl.