To a stirred solution of 1,3-dihydro-1-{1-[4-oxocyclohex-1-yl]piperidin-4-yl}-2H-benzimidazol-2-one (100 mg) in dry tetrahydrofuran (25 mL) at -78° C., under nitrogen, was added L-Selectride (0.385 mL of a 1.0M solution in tetrahydrofuran). The reaction mixture was stirred at -78° C. for 30 min, then quenched with water (3 mL). The solution was allowed to warm to room temperature and ethyl acetate (50 mL) was added. The organic layer 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 cis-1,3-dihydro-1-{1-[4-hydroxycyclohex-1-yl]piperidin-4-yl}-2H-benzimidazol-2-one (43 mg) as a colorless solid: 1H NMR (400 MHz, CD3OD) 7.42 (m, 1H), 7.05 (m, 3H), 4.32 (m, 1H), 3.94 (m, 1H), 3.17 (m, 2H), 2.53 (m, 5H), 1.88-1.71 (m, 8H), 1.59-1.53 (m, 2H). The hydrochloride salt was precipitated from diethyl ether/methylene chloride: analysis calculated for C18H25N3O2.HCl.0.70 H2O C: 59.48, H: 7.32, N: 11.56; found C: 59.46, H: 7.28, N: 11.23.
