Patent ID: 8563728

Claim:
A process for the preparation of (5α,17β)-N-[2,5-bis(trifluoromethyl)phenyl]-3-oxo-4-azaandrost-1-ene-17-carboxamide (Dutasteride) of Formula (I), which comprises: (i) reacting 4-aza-5α-androst-1-en-3-one-17β-carboxylic acid (VII), with sulfonic acid anhydride (RSO 2 ) 2 O in presence of base in a solvent to produce a compound of Formula (XIII), wherein R represents C 1-6 halo alkyl, C 6-10 halo aryl; (ii) condensing compound of Formula (XIII) with 2,5-bis(trifluoromethyl)aniline (III), to produce Dutasteride (I).