To a stirred suspension of [10-chloro-1-(3,5-dichloropyridin-2-yl)-2,3,4,5-tetrahydro-1H-[1,3]diazepino[1,2-a]benzimidazol-7-yl]methanol (376 mg, 0.946 mmol) in acetonitrile (10 mL) was added Dess-Martin reagent (481 mg, 1.14 mmol) at room temperature. After 2 h, the reaction mixture was diluted with ethyl acetate, washed with aqueous sodium hydrogen carbonate and brine, dried over sodium sulfate, filtered, and concentrated in vacuo. The residue was dissolved in tetrahydrofuran (10 mL) and a solution of ethyl magnesium bromide in diethyl ether (3.0 M, 568 μL, 1.70 mmol) was added at −78° C. After 30 min, the reaction mixture was quenched with aqueous ammonium chloride, diluted with ethyl acetate, washed with water and brine, dried over sodium sulfate, filtrated, and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel eluting with a 0-40% ethyl acetate/n-hexane gradient mixture to give the title compound as a colorless solid (301 mg, 0.707 mmol, 75%).
