A mixture of 2-{5-chloro-2-[3-(4-methylpiperazin-1-yl)-propylamino]-pyrimidin-4-yl}-benzo[b]thiophene-4-carboxylic acid tri-hydrochloride (425 mg, 0.960 mmol), tert-butylcarbazate (398 mg, 3.01 mmol), diisopropylethylamine (0.500 mL, 2.87 mmol), (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (510 mg, 1.15 mmol), and lithium chloride (498 mg, 11.7 mmol) in DMF (6 mL) is heated at 50° C. for 20 hours. After cooling to room temperature, the solvent is removed and the residue is subjected to chromatography on silica gel, eluting with 2.0 M NH3/MeOH) in dichloromethane 0-10%, to give N′-(2-{5-chloro-2-[3-(4-methylpiperazin-1-yl)-propylamino]-pyrimidin-4-yl}-benzo[b]thiophene-4-carbonyl)-hydrazinecarboxylic acid tert-butyl ester (441 mg, 82% yield).
