Process for the preparation of Roflumilast

摘要

The present invention relates to an improved process for the preparation of Roflumilast. The present invention also relates to crystalline Form-I of Roflumilast.

主权项

1. A process for the preparation of Roflumilast comprising the steps of:
a) reacting 4-Difluoromethoxy-3-hydroxy benzaldehyde of Formula II with a cyclopropylmethyl compound of Formula III in the presence of an organic base to obtain 3-cyclopropylmethoxy-4-Difluoromethoxy benzaldehyde of Formula IV wherein X is a leaving group, b) oxidising the obtained aldehyde compound of Formula IV into 3-cyclopropylmethoxy-4-Difluoromethoxy benzoic acid of Formula V, c) converting 3-cyclopropylmethoxy-4-Difluoromethoxy benzoic acid of Formula V to its acid halide and condensing with 4-amino 3,5-Dichloropyridine in the presence of base to obtain Roflumilast, and d) optionally purifying Roflumilast in an organic solvent to get pure Roflumilast.