[BH4-].[Na+].[F:3][C:4]1[C:5]([C:10]2[CH2:15][CH2:14][CH2:13][C:12](=[O:16])[CH:11]=2)=[N:6][CH:7]=[CH:8][N:9]=1.[Cl-].[NH4+]>CO>[F:3][C:4]1[C:5]([C@@H:10]2[CH2:15][CH2:14][CH2:13][C@H:12]([OH:16])[CH2:11]2)=[N:6][CH:7]=[CH:8][N:9]=1.[F:3][C:4]1[C:5]([C@H:10]2[CH2:15][CH2:14][CH2:13][C@H:12]([OH:16])[CH2:11]2)=[N:6][CH:7]=[CH:8][N:9]=1Sodium borohydride (295 mg, 7.80 mmol) was added was added portion wise to a solution of 3-(3-fluoropyrazin-2-yl)cyclohex-2-enone (500 mg, 2.60 mmol) in MeOH (15 ml) at RT. After completion of the addition the reaction mixture was stirred at RT for 30 minutes. It was then cooled in an ice-water bath, saturated aqueous ammonium chloride (25 ml) was added dropwise, and the resulting mixture was extracted with EtOAc (2×100 ml). The combined organic layers were washed with brine and dried over sodium sulfate. Filtration and concentration under reduced pressure, followed by flash chromatography on silica gel (0% to 20% EtOAc in hexanes) afforded (rac)-cis-3-(3-fluoropyrazin-2-yl)cyclohexanol and (rac)-trans-3-(3-fluoropyrazin-2-yl)cyclohexanol as colorless oils. MS (ESI, pos. ion) m/z: 197.0 (M+1) and MS (ESI, pos. ion) m/z: 197.0 (M+1), respectively. IC50 (uM) +++++.
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