Patent ID: 8912325

Claim:
A process for the preparation of imatinib mesylate of formula Ia, comprising: a) reacting an amine intermediate of formula II with an intermediate of formula III in the presence of a base in an organic solvent, in a ratio of at least 1.5 molar equivalents of the intermediate of formula III per molar equivalent of the intermediate of formula II; wherein X is selected from the group consisting of —OH and halogen; b) isolating imatinib of formula I from the reaction mixture, wherein said imatinib of formula I contains less than 50 ppm of the amine intermediate of formula II; c) optionally, purifying imatinib of formula I; and d) reacting imatinib with methanesulfonic acid to form imatinib mesylate of formula Ia, wherein said imatinib mesylate produced in step (d) contains less than 20 ppm of the intermediate of formula II.