To a stirred and cooled (0° C.) solution of benzyl (S)-4-(2-amino-1-propoxy)benzoate (1.50 g, 5.26 mmol) and 2-nitrobenzaldehyde (0.87 g, 5.76 mmol) in MeOH—AcOH (16 mL, 15:1, v/v) was added NaBH3CN (1.65 g, 26.3 mmol), and the resulting mixture was stirred at room temp overnight. The mixture was quenched by sat. NaHCO3 and extracted with EtOAc. The extract was washed with brine, dried over Na2SO4 and evaporated. The residue was purified by column chromatography on silica-gel with CHCl3 to 5% MeOH in CHCl3 as eluent to give 931 mg (42%) benzyl (S)-4-[2-(2-nitrobenzylamino)-1-propoxy]benzoate as a yellow oil. 1H-NMR (CDCl3) δ 1.21 (d, 3 H, J=6.4 Hz), 3.13–3.18 (m, 1 H), 3.88–3.97 (m, 2 H), 4.06–4.20 (m, 2 H), 5.34 (s, 2 H), 6.89–6.94 (m, 2 H), 7.29–7.65 (m, 8 H), 7.94–8.03 (m, 3 H); MS (FAB) m/z 421 (M++1).
