反应详情

温度

-20 °C

To a solution of ethyl 2-((2-methyl-1,3-dioxolan-2-yl)methyl)pentanoate (9.8 g; 42.55 mmol) in hexane (106 mL) at −78° C. under nitrogen atmosphere was added borontribromide (55 mL; 55 mmol; 1M in dichloromethane) and the reaction mixture was stirred at −20° C. for 2 h. Water (50 mL) and ethyl acetate (50 mL) were added to the reaction mixture and the layers were separated. The aqueous layer was extracted with ethyl acetate and the combined organic layers were dried over sodium sulfate, filtered and concentrated under reduced pressure. Purification by flash chromatography on silica gel using a gradient of ethyl acetate (1-40%) in heptane furnished 6.41 g (81%) of ethyl 4-oxo-2-propylpentanoate as a light yellow oil. ESI/APCI(+): 187 (M+H). 1H NMR (CDCl3): δ 4.15 (q, J=7.14 and 14.25 Hz, 2H, CO2CH2CH3); 2.88 (m, 2H, CH2); 2.51 (m, 1H, CH); 2.16 (s, 3H, CH3); 1.62-1.23 (m, 7H, CH2CH2CH3); 0.90 (t, J=7.14 Hz, 3H, CO2CH2CH3).

1. customthe layers were separated
2. extractionThe aqueous layer was extracted with ethyl acetate
3. dry with materialthe combined organic layers were dried over sodium sulfate
4. filtrationfiltered
5. concentrationconcentrated under reduced pressure
6. customPurification by flash chromatography on silica gel using a gradient of ethyl acetate (1-40%) in heptane