Borane;2-methylpropan-2-amine → HCID 178518597, compound

To a stirred solution of 1,3-dihydro-1-{1-[4-oxocyclohex-1-yl]piperidin-4-yl}-2H-benzimidazol-2-one (100 mg) in methanol (4 mL) at 0° C., under nitrogen, was added tert-butylamine-borane (28 mg). The reaction mixture was stirred at 0° C. for 1 h, then quenched with water (2 mL) and concentrated to remove the methanol. The resulting oil was dissolved in ethyl acetate (50 mL) and the organic solution was washed with saturated sodium carbonate (10 mL), then water (10 mL), then brine (10 mL) and then dried over sodium sulfate. Concentration under reduced pressure yielded trans-1,3-dihydro-1-{1-[4-hydroxycyclohex-1-yl]piperidin-4-yl}-2H-benzimidazol-2-one (75 mg) as a colorless solid: 1H NMR (400 MHz, CD3 OD) 7.42 (m, 1H), 7.04 (m, 3H), 4.28 (m, 1H), 3.50 (m, 1H), 3.09 (m, 2H), 2.45 (m, 5H), 2.03-1.94 (m, 4H), 1.78-1.75 (m, 2H), 1.44-1.26 (m, 4H). The hydrochloride salt was precipitated from diethyl ether/chloroform: analysis calculated for C18H25N3O2.HCl.0.50 H2O.0.70 CHCl3C: 50.54, H: 6.28, N: 9.45; found C: 50.54, H: 6.19, N: 9.64.