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

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Reaction Steps

Methylmagnesium bromide (1.0 M solution in tetrahydrofuran, 0.49 mL, 0.490 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 (163 mg, 0.328 mmol) and [1,3-bis(diphenylphosphino)propane]dichloronickel (17.8 mg, 0.0328 mmol) in tetrahydrofuran (1.3 mL) at 0° C., and the mixture was stirred at room temperature for 7 hr. The mixture was diluted with water 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 30-100% 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 contained 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 (49.8 mg, 0.105 mmol, 32%)

Provenance & Evidence