反应详情

Another solution was prepared by adding dropwise a 1.6M hexane solution of butyllithium (38.8 mL, 62.1 mmol) to a cooled (-78°) solution of (S)-4-(phenylmethyl)-2-oxazolidinone [10.0 g, 56.4 mmol, described by L. N. Predgen et al., J. Org. Chem., 54, 3231 (1989)] in THF (250 mL). The freshly prepared second solution was kept at -78° for 30 min and then quickly added via a cannula to the solution of mixed anhydride at -78°. The reaction mixture was stirred at -78° for 3 h. Thereafter, H2O (100 mL) and 10% aqueous HCl (50 mL) were added. The resulting mixture was extracted with EtOAc (2×250 mL). The combined extract was washed with a saturated aqueous solution of NaHCO3 and with brine, dried (Na2SO4) and concentrated under reduced pressure. Purification of the residue by flash chromatography (SiO2, eluent: hexane-EtOAc, 15:1) gave (4S)-3-(1-oxo-4-pentenyl)-4-(phenylmethyl)-2-oxazolidinone (10.85 g, 74%) as a colorless oil, 1H NMR (CDCl3) δ 7.34-7.2 (m,5H), 6.0-5.8 (m,1H), 5.16-5.0 (m,2H), 4.7 (m,1H), 4.2 (m,2H), 3.3 (dd,J=3.1 Hz,13.2 Hz,1H), 3.1-3.0 (m,2H), 2.75 (dd,J=9.6 Hz,13.3 Hz,1H), 2.5 (m,2H), mass spectrum: 260 (M+H)+.

1. customAnother solution was prepared
2. extractionThe resulting mixture was extracted with EtOAc (2×250 mL)
3. extractionThe combined extract
4. washwas washed with a saturated aqueous solution of NaHCO3 and with brine
5. dry with materialdried (Na2SO4)
6. concentrationconcentrated under reduced pressure
7. customPurification of the residue by flash chromatography (SiO2, eluent: hexane-EtOAc, 15:1)