To a solution of 1-[9-chloro-1-(2,4-dichlorophenyl)-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazol-6-yl]propan-1-ol (150 mg, 0.365 mmol), methoxyacetic acid (0.0453 mL, 0.59 mmol), triethylamine (0.25 mL, 1.79 mmol) and 4-dimethylaminopyridine (48.0 mg, 0.39 mmol) in tetrahydrofuran (5.0 ml) was added 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (170 mg, 0.887 mmol) at room temperature. The mixture was stirred at room temperature for 24 hr. Water was added to the reaction mixture and the mixture was extracted with ethyl acetate. The organic layer was washed with water and brine, dried over anhydrous magnesium sulfate and concentrated in vacuo. The residue was purified by flash chromatography on silica gel eluting with a 25-80% ethyl acetate/n-hexane gradient mixture and recrystallization from 2-propanol/diisopropyl ether to give the title compound (98.4 mg, 0.204 mmol, 56%) as colorless crystals.
