Trifluoroacetic acid → 9-Chloro-1-[2-(difluoromethoxy)-4,6-dimethylpyrimidin-5-yl]-6-[1-(difluoromethoxy)-2,2,2-trifluoroethyl]-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazole

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Reaction Steps

A mixture of 5-{9-chloro-6-[1-(difluoromethoxy)-2,2,2-trifluoroethyl]-3,4-dihydropyrimido[1,2-a]benzimidazol-1(2H)-yl}-4,6-dimethylpyrimidin-2-ol (290 mg, 0.607 mmol), benzyltriethylammonium chloride (6.9 mg, 0.0303 mmol), and 8N sodium hydroxide (2.4 mL) in tetrahydrofuran (2.4 mL) was stirred at room temperature under chloro(difluoro)methane atmosphere for 60 min. 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 20-50% ethyl acetate/n-hexane gradient mixture. The filtrate was concentrated in vacuo to give the solid, which was purified by preparative HPLC to give a mixture containing an intermediate of the title compound as the trifluoroacetic acid salt. The mixture was washed with aqueous sodium hydrogen carbonate and extracted with ethyl acetate. The extract was washed with brine, dried over magnesium sulfate, filtered and concentrated in vacuo to give the solid, which was recrystallized from ethyl acetate/n-hexane to give the title compound as a colorless crystal (84.0 mg, 0.159 mmol, 26%).

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