Synthetic method of imatinib mesylate

The invention provides a synthetic method of a molecular targeted therapeutic drug imatinib mesylate aiming at chronic myelogenous leukemia and gastrointestinal stromal tumor, and belongs to the field of pharmaceutical synthesis. The method comprises the following steps: a reaction is carried out for 4-(chloromethyl)benzoic acid and oxalyl chloride in order to obtain 4-(chloromethyl)benzoyl chloride; and in the effects of a catalyst, reactions of N-(5-amino-2-methylphenyl)-4-(3-pyridyl)-2-pyrimidineamine are carried out with 4-(chloromethyl)benzoyl chloride, N-methylpiperazine, and methanesulfonic acid in order, 4-chloromethyl-N-[4-methyl-3-[4-(3-pyridyl)-2-pyrimidinyl]amino-phenyl]-benzamide, 4-[(4-methyl-1-piperazinyl)methyl]-N-[4-methyl-3-[4-(3-pyridyl)-2-pyrimidinyl]amino-phenyl]-benzamide and 4-[(4-methyl-1-piperazinyl)methyl]-N-[4-methyl-3-[4-(3-pyridyl)-2-pyrimidinyl]amino-phenyl]-benzamide methanesulfonate are obtained step by step, and imatinib mesylate is obtained (as shown in figure). The synthetic