[BH4-].[Na+].[C:3]([C:6]1[CH:23]=[CH:22][C:9]([C:10]([NH:12][CH2:13][CH2:14][C:15]([O:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[O:16])=[O:11])=[CH:8][CH:7]=1)(=[O:5])[CH3:4]>CO>[OH:5][CH:3]([C:6]1[CH:23]=[CH:22][C:9]([C:10]([NH:12][CH2:13][CH2:14][C:15]([O:17][C:18]([CH3:20])([CH3:19])[CH3:21])=[O:16])=[O:11])=[CH:8][CH:7]=1)[CH3:4]Sodium borohydride (0.28 g, 7.4 mmol) was added as solid to a solution of tert-butyl N-(4-acetylbenzoyl)-β-alaninate (2.11 g, 7.24 mmol) in MeOH (50 ml). After stirring at room temperature for 30 min, the reaction was quenched by adding ethyl acetate (150 ml) and 2N HCl (50 ml). The organic layer was washed with 1 N HCl 2×, brine 2×, and dried over Na2SO4. Evaporation of solvent and vacuum drying afforded tert-butyl N-[4-(1-hydroxyethyl)benzoyl]-β-alaninate as a colorless oil. NMR (CDCl3) δ: 1.46 (s, 9H); 1.49 (d, J=6.6 Hz, 3H); 2.55 (t, J=6.0 Hz, 2H); 3.67 (q, J=6.0 Hz, 2H); 4.94 (q, J=6.6 Hz, 1H); 6.88 (br, 1H); 7.42 (d, J=8.2 Hz, 2H); 7.72 (d, J=8.2 Hz, 2H). MS C16H23NO4 Cald: 293.16; Obsd: (M+Na) 316.12.
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