[Cl:1][C:2]1[CH:9]=[CH:8][C:5]([CH:6]=O)=[CH:4][C:3]=1[N+:10]([O-:12])=[O:11].[Cl:13][C:14]1[CH:15]=[C:16]([C@H:20]([NH2:22])[CH3:21])[CH:17]=[CH:18][CH:19]=1.C(O)(=O)C.[BH-](OC(C)=O)(OC(C)=O)OC(C)=O.[Na+]>ClCCCl>[Cl:1][C:2]1[CH:9]=[CH:8][C:5]([CH2:6][NH:22][C@@H:20]([C:16]2[CH:17]=[CH:18][CH:19]=[C:14]([Cl:13])[CH:15]=2)[CH3:21])=[CH:4][C:3]=1[N+:10]([O-:12])=[O:11]To a solution of 4-chloro-3-nitrobenzaldehyde 1 (1.71 g, 9.2 mmol) and (R)-1-(3-chlorophenyl)ethanamine (1.115 g, 7.2 mmol) in DCE (15 mL) at room temperature was added acetic acid (2.0 mL, 35 mmol) and NaBH(OAc)3 (2.23 g, 11 mmol). The reaction mixture was stirred at room temperature for 2 d, quenched with saturated NaHCO3, and diluted with EtOAc. The organic phase was washed with NaHCO3 (1×), brine (1×), dried over MgSO4, filtered, and concentrated in vacuo. Purification by flash column chromatography on silica gel (eluted with 10% to 40% EtOAc in hexanes) gave (R)—N-(4-chloro-3-nitrobenzyl)-1-(3-chlorophenyl)ethanamine 30 (2.03 g, 87% yield) as a pale yellow oil. 1H NMR (400 MHz, CDCl3) δ 1.37 (d, J=6.7 Hz, 3H), 3.66 (s, 2H), 3.77 (q, J=6.7 Hz, 1H), 7.18-7.32 (m, 5H), 7.44-7.48 (m, 2H), 7.83 (s, 1H). Mass spectrum: calculated for C15H14Cl2N2O2 324.0. found 325.1 (M++1).
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