US Patent 7989636 Process for the preparation of pure anastrozole

A process for the preparation of anastrozole which comprises: a) brominating 3,5-bis(2-cyanoprop-2-yl)toluene (II) in an organic solvent using a brominating agent to obtain 3,5-bis(2-cyanoprop-2-yl)benzylbromide (III); b) heating the reaction mass of step a) to the reflux temperature of the organic solvent for a period of time no longer than 3 hours; c) isolating and purifying the bromo intermediate (III) using an organic solvent; d) alkylating the bromo intermediate in the presence of a base, optionally a phase transfer catalyst, a 1,2,4-triazole and an organic solvent to obtain anastrozole; and e) isolating and purifying the anastrozole from an organic solvent.