A mixture of methyl [5-(4-nitrobenzyl)imidazo[1,2-c]pyrimidin-8-yl]acetate (28 mg, 0.09 mmol) and Pd/C (wet, 3 mg) in methanol (1 mL) was stirred under hydrogen atmosphere for 1 hour. After the removal of Pd/C by filtration through a Celite pad, the filtrate was concentrated in vacuo. The resulting crude methyl [5-(4-aminobenzyl)imidazo[1,2-c]pyrimidin-8-yl]acetate (26 mg, 0.09 mmol) was dissolved with dichloromethane (1 mL). To this solution was added 3,4-dichloro-benzoic acid (20.1 mg, 0.11 mmol), 1-hydroxybenzotriazole (14.2 mg, 0.11 mmol), triethylamine (0.037 mL, 0.26 mmol) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (21.9 mg, 0.11 mmol) at room temperature. The mixture was stirred at room temperature overnight, and diluted with ethyl acetate. The solution was washed with water and brine, dried over sodium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by preparative TLC (silica gel, chloroform:methanol, 19:1) to give methyl (5-{4-[(3,4-dichloro-benzoyl)amino]benzyl}imidazo[1,2-c]pyrimidin-8-yl)acetate (29 mg, 70%) as slightly yellow oil.
