A solution of propylphosphonic anhydride in N,N-dimethylformamide (Fluka, Buchs, Switzerland; 1.3 mL of 50%, 2.25 mmol) is added dropwise to a stirred mixture of 4-methyl-N-[4-(3-pyridinyl)-2-pyrimidinyl]-1,3-benzenediamine (416 mg, 1.5 mmol), 4-[(3-oxo-1-piperazinyl)methyl]benzoic acid (351 mg, 1.5 mmol) and triethylamine (1.7 mL, 12 mmol) in dry N,N-dimethylformamide (4 mL). The mixture is stirred for 17 hours at room temperature and then treated with saturated aqueous sodium hydrogen carbonate solution (100 mL). The resulting precipitate is filtered, washed with water, dried and recrystallised from methanol to give the title compound as a cream crystalline solid.
