[NH2:1][CH:2]([CH3:6])[CH2:3][CH2:4][OH:5].[Br:7][C:8]1[CH:15]=[CH:14][C:11]([CH:12]=O)=[C:10]([F:16])[CH:9]=1.[BH4-].[Na+]>CO.[Cl-].[Cl-].[Zn+2]>[Br:7][C:8]1[CH:15]=[CH:14][C:11]([CH2:12][NH:1][CH:2]([CH3:6])[CH2:3][CH2:4][OH:5])=[C:10]([F:16])[CH:9]=1A mixture of 3-aminobutan-1-ol (1.8 g, 20.2 mmol), 4-bromo-2-fluorobenzaldehyde (4.1 g, 20.2 mmol), and ZnCl2 (28 mg, 0.202 mmol) in MeOH (20 mL) was stirred at ambient temperature for 1 hour. To the mixture at 0° C. was added NaBH4 (3.84 g, 101 mmol) and stirred at ambient temperature for 22 hours. The reaction mixture was quenched with H2O and extracted with EtOAc (30 mL×4). The extracts were combined, washed with brine (20 mL), dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by silica gel chromatography using petroleumn ether/EtOAc (5/1) and EtOAc/NEt3 (500/1) as eluting solvents to afford 3-(4-bromo-2-fluorobenzylamino)butan-1-ol as corlorless oil (3.2 g, 57%). 1H-NMR (500 MHz, CDCl3) δ 7.25-7.20 (m, 3H), 3.90 (d, 1H), 3.87-3.83 (m, 1H), 3.77-3.173 (m, 2H), 3.00-2.93 (m, 2H), 1.77-1.71 (m, 1H), 1.59-1.52 (m, 1H), 1.20 (d, 3H); LCMS (ESI): m/z=276.1 [M+H]+.
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