AN IMPROVED PROCESS FOR THE PREPARATION OF RIMONABANT

摘要

The present invention relates to an industrially advantageous, eco-friendly process for the re aration of rimonabant of formula-(I), staring from l-(4-chlorophenyl)-propan-l-one in high yields and high purity by using mild reaction conditions and avoiding use of toxic and expensive reagents, as well as stringent reaction conditions. The present invention relates to an isolated impurity of rimonabant, referred to as 'Bis impurity' and removal thereof.1 The present invention also relates to novel crystalline form-Ill of rimonabant and processes for its preparation and conversion to form-I of rimonabant.