反应详情

温度

145 °C

A mixture of triethyl orthoacetate (18.6 ml, 102 mmol), 2-(3,3,5,5-tetramethyl-cyclohexylidene)ethanol (3) (4.63 g, 25.4 mmol) and propionic acid (0.19 ml, 2.5 mmol) was heated at 145° C. for 10 h. Ethanol was distilled off from the mixture in the course of reaction. The reaction mixture was cooled and poured into water (100 ml). The aqueous phase was extracted with hexane (250 ml) and the combined organic phases were washed with 5% aqueous KHSO4 (50 ml) and brine (50 ml). The extract was dried over MgSO4, filtered and evaporated. The residue was purified by flash chromatography on silica gel (light petroleum ether and light petroleum ether-ethyl acetate, 100:2) to give 16 (4.64 g, 73%) as an oil. 1H-NMR (CDCl3, TMS): 0.91 (6H, s, 3,5-CH3); 1.01 (6H, s, 3,5-CH3); 1.23 (3H, t, 7 Hz, ethyl CH3) 1.00-1.30 (4H, m, 4-CH2 and 2,6-CH); 1.86 (2H, d, 13 Hz, 2,6-CH); 2.22 (2H, s, CH2C═O); 4.08 (2H, q, 7 Hz, ethyl CH2); 5.06 and 5.07 (total 2H, both d, 11 and 17.5 Hz, ═CH2) and 5.95 ppm (1H, dd, 11 and 17.5 Hz, —CH═).

1. distillationEthanol was distilled off from the mixture in the course of reaction
2. temperatureThe reaction mixture was cooled
3. additionpoured into water (100 ml)
4. extractionThe aqueous phase was extracted with hexane (250 ml)
5. washthe combined organic phases were washed with 5% aqueous KHSO4 (50 ml) and brine (50 ml)
6. dry with materialThe extract was dried over MgSO4
7. filtrationfiltered
8. customevaporated
9. customThe residue was purified by flash chromatography on silica gel (light petroleum ether and light petroleum ether-ethyl acetate, 100:2)