A mixture of 1-[9-chloro-1-(2,4-dichlorophenyl)-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazol-6-yl]propan-1-ol (460 mg, 1.12 mmol), potassium carbonate (201 mg, 1.46 mmol) and methyl iodide (207 mg, 1.46 mmol) in N,N-dimethylformamide (4.5 mL) was stirred at room temperature for 9 hr. The mixture was diluted with aqueous saturated ammonium chloride, and extracted with ethyl acetate. The combined organic layer was washed with brine, dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel eluting with a 5-40% ethyl acetate/n-hexane gradient mixture. The filtrate was concentrated in vacuo to give the solid, which was recrystallized from ethyl acetate/diisopropyl ether to give the title compound as a colorless crystal (363 mg, 0.855 mmol, 76%).
