反应详情

To a stirred solution of the intermediate ethyl-(5S)-6-phenyl-5-[(tert-butyloxy-carbonyl)-amino]4-oxo-hexanoate (0.250 g, 0.716 mmol) in THF-MeOH (8:2 ratio)(10 mL) was added 0.5N LiOH (10 mL) and the resulting mixture was stirred at room temperature for 3 h. The reaction mixture was then neutralized with glacial acetic acid and then extracted with EtOAc (3×25 mL). The organic extract was dried over anhydrous MgSO4 and evaporation of the solvent afforded a crude yellow residue. Column chromatography on silica gel elution with 50% EtOAc-hexane afforded (5S)-6-phenyl-5-[(tert-butyloxycarbonyl)-amino]-4-oxo-hexanoic acid 9 as a cream yellow solid (0.225 g, 98%); mp 108-110° C.; Rf 0.41 (50% EtOAc-hexane); IR (KBr) ν 1730 (CO), 3200 (broad, COOH) cm−1; 1H NMR (300 MHz, CDCl3) δH 1.39 (9H, s, (CH3)3), 2.62-2.73 (4H, m, —COCH2CH2CO), 2.94 (1H, dd, J=6.9 and 13.8 Hz, —CHαPh), 3.10 (1H, dd, J=6.0 and 13.8 Hz, —CHβPh), 4.54 (1H, m, —CH—), 5.08 (1H, d, J=8.1 Hz, —NH—) and 7.13-7.35 (5H, m, Ar—H); 13C NMR (75 MHz, CDCl3) δC 27.5, 28.3, 35.0, 37.5, 60.1, 80.1, 127.0 (2C), 128.7 (2C), 129.2 (2C), 129.3, 136.2, 155.4, 177.4 and 207.4; HRMS m/z calcd for C17H23NO5 (M+) 321.15831, found 321.15762. Anal. Calcd. for C17H23NO5: C, 63.54; H, 7.21; N, 4.36. Found: C, 63.55; H, 7.34; N, 4.30.

1. extractionextracted with EtOAc (3×25 mL)
2. extractionThe organic extract
3. dry with materialwas dried over anhydrous MgSO4 and evaporation of the solvent
4. customafforded a crude yellow residue
5. washColumn chromatography on silica gel elution with 50% EtOAc-hexane