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

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Reaction Steps

i-Propylmagnesium chloride (1.0 M solution in tetrahydrofuran, 0.76 mL, 0.760 mmol) was added dropwise to a stirred suspension of 9-chloro-1-(2-chloro-4,6-dimethylpyrimidin-5-yl)-6-[1-(difluoromethoxy)-2,2,2-trifluoroethyl]-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazole (189 mg, 0.381 mmol) and [1,3-bis(diphenylphosphino)propane]dichloronickel (20.7 mg, 0.0381 mmol) in tetrahydrofuran (1.5 mL) at 0° C., and the mixture was stirred at room temperature for 14 hr. The mixture was diluted with aqueous 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 50-100% 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 (19.1 mg, 0.0379 mmol, 10%).

Provenance & Evidence