Process for preparation of penam derivatives from cepham derivatives

摘要

The present invention relates to a process for preparing 2alpha-methyl-2beta-substituted methyl penam derivatives from cepham derivatives, more particularly the present invention provides a novel process for preparing 2beta-heterocyclyl methyl penam derivatives of the formula (I) wherein R1 represents carboxylic acid protecting group; R2 and R3 may be same or different and independently represent hydrogen, halogen, NH2, acylamino, phthalimido with a proviso that both R2 and R3 are not NH2, acylamino, phthalimido; Het represents a 5 or 6 membered nitrogen containing heterocycle ring system having one or more heteroatoms selected from O, S, or N.