[BH4-].[Na+].[Br:3][C:4]1[CH:5]=[CH:6][C:7]([CH:10]2[CH2:15][CH2:14][C:13](=[O:16])[CH2:12][CH2:11]2)=[N:8][CH:9]=1.O>C(O)C>[Br:3][C:4]1[CH:5]=[CH:6][C:7]([C@H:10]2[CH2:15][CH2:14][C@H:13]([OH:16])[CH2:12][CH2:11]2)=[N:8][CH:9]=1.[Br:3][C:4]1[CH:5]=[CH:6][C:7]([C@@H:10]2[CH2:15][CH2:14][C@H:13]([OH:16])[CH2:12][CH2:11]2)=[N:8][CH:9]=1Sodium borohydride (4.58 g) was added under ice cooling to a solution of 4-(5-bromopyridin-2-yl)cyclohexanone (7.9 g) in ethanol (120 ml), and stirred at the same temperature for an hour. After completion of the reaction, water was added under ice cooling, the organic solvent was evaporated and extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous sodium sulfate and concentrated. The resulting residue was purified with silica gel column chromatography (n-hexane/ethyl acetate) to give trans-4-(5-bromopyridin-2-yl)cyclohexanol (4.94 g) as a white solid, and cis-4-(5-bromopyridin-2-yl)cyclohexanol (1.16 g) as a colorless oil.
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