[F:1][C:2]1[C:22]([F:23])=[CH:21][CH:20]=[CH:19][C:3]=1[C:4]([C@@H:6]1[CH2:11][CH2:10][CH2:9][N:8]([C:12]([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13])[CH2:7]1)=[O:5].[BH4-].[Na+]>CO>[F:1][C:2]1[C:22]([F:23])=[CH:21][CH:20]=[CH:19][C:3]=1[CH:4]([OH:5])[C@@H:6]1[CH2:11][CH2:10][CH2:9][N:8]([C:12]([O:14][C:15]([CH3:17])([CH3:16])[CH3:18])=[O:13])[CH2:7]1To a solution of (R)-tert-butyl 3-(2,3-difluorobenzoyl)piperidine-1-carboxylate (10 g, 30.8 mmol) in MeOH (200 mL) was added NaBH4 (9.3 g, 246 mmol) in portions while the temperature was lower than 40° C. After addition, the mixture was stirred at rt for 2-3 hrs. The solvent was removed in vacuo to afford a residue which was partitioned between water and ethyl acetate. The organic layer was washed with water and brine, dried over Na2SO4 and evaporated to give the crude product (R)-tert-butyl 3-((2,3-difluorophenyl)(hydroxy)methyl)piperidine-1-carboxylate (10 g, 99%), which was used in the next step without purification. 1H NMR (CDCl3, 400 MHz) δ 7.22 (m, 1H), 7.08 (m, 2H), 4.85 (t, 1H), 3.94 (d, 0.5H), 3.78 (d, 1H), 3.55 (m, 0.5H), 3.28 (d, 1H), 2.65 (m, 1H), 1.90 (m, 2H), 1.68 (m, 3H), 1.44 (d, 9H).
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