Patent ID: 7829720

Claim:
A process for preparing atazanavir bisulfate in the form of Form A crystals, which comprises reacting a solution of atazanavir free base in an organic solvent, said organic solvent being selected from the group consisting of acetone and a mixture of acetone and N-methylpyrrolidone, in which solvent the bisulfate salt of atazanavir is substantially insoluble, with a first portion of concentrated sulfuric acid in an amount to react with from about 5 to about 15% by weight of the atazanavir free base, adding seeds of Form A crystals of atazanavir bisulfate to the reaction mixture, as crystals of atazanavir bisulfate form, adding additional concentrated sulfuric acid in multiple stages at an increasing rate to effect formation of atazanavir bisulfate Form A crystals, and drying the atazanavir bisulfate Form A crystals.