反应详情

α(R)-Methylcyclohexanepropionic acid chloride: Under argon, a 1.6M hexane solution of burylithium (100 mL, 160 mmol) was added to a cooled solution (-30° to -40°) of 4(S)-(1-methylethyl)-2-oxazolidinone (20.7 g, 160 mmol), see L. N. Pridgen et al., J. Org. Chem., 54, 3231 (1989), in dry THF (200 mL). After 15 min, the mixture was cooled to -78° and propionyl chloride (14.2 mL, 163 mmol) was added. After 5 min at -78°, the reaction mixture was allowed to warm to 0°. The mixture then was treated with a saturated aqueous solution of NaHCO3 (500 mL). The resultant mixture was extracted with EtOAc (2 X). The combined organic extracts were dried (MgSO4) and concentrated to afford a yellow liquid. This material was purified by flash chromatography [SiO2, eluent: EtOAc-hexane (1:10 to 1:4)] to provide (4S)-(1-methylethyl)-3-(1-oxopropyl)-2-oxazolidinone as a clear liquid (10.9 g, 74% yield). 1H NMR (400 MHz, CDCl3) δ 4.46-4.41 (m, 1H), 4.29-4.19 (m, 2H), 3.03-2.86 (m, 2H), 2.43-2.33 (m, 1H), 1.17 (t, J=7.3 Hz, 3H), 0.92 (d, J=7 Hz, 3H), 0.88 (d, J=7 Hz, 3H).

1. temperaturethe mixture was cooled to -78°
2. waitAfter 5 min at -78°
3. temperatureto warm to 0°
4. extractionThe resultant mixture was extracted with EtOAc (2 X)
5. dry with materialThe combined organic extracts were dried (MgSO4)
6. concentrationconcentrated
7. customto afford a yellow liquid
8. customThis material was purified by flash chromatography [SiO2, eluent: EtOAc-hexane (1:10 to 1:4)]