Patent ID: 6936711

Claim:
A process for the preparation of 2β-heterocyclyl methyl penam derivatives of the formula (I), wherein, R 1 carboxylic acid protecting group; R 2 and R 3 may be same or different and independently represent hydrogen, halogen, NH 2, acylamino, phthalimido with provisos that R 2 and R 3 are not both NH 2, R 2 and R 3 are not both acylamino, and R 2 and R 3 are not both phthalimido; and wherein Het represents a 5 or 6-membered nitrogen containing a heterocycle ring system having one or more heteroatoms selected from O, S, or N, in which a H is bound to the nitrogen contained in the ring, said process comprising: (i) reacting a compound of formula (VII) wherein, L represents a leaving group and all other substituents are as defined above with heterocyclic amine of formula (VIII) Het-H (VIII) wherein, Het is as defined above, in the presence of a solvent and base at a temperature in a range of −10 to 110° C. to produce a compound of formula (IX) wherein all substituents are as defined above and (ii) oxidizing the compound of formula (IX) using conventional oxidizing agents in the presence of an organic acid to produce a compound of formula (I).