反应详情

A mixture of 3β,24-bis(tert-butyldimethylsilyloxy)-4,4-dimethylchola-5,7-diene (18.8 g) in 99.9% ethanol (375 ml), benzene (55 ml) and concentrated hydrochloric acid (55 ml) is heated to reflux for 4 hours. After standing overnight at room temperature, the reaction mixture is concentrated under reduced pressure. Crystallization of the remanens from ethanol/water gives 8.44 g of the title compound. Melting point: 203-208° C. 1H-NMR (CDCl3, 400 MHz): δ=5.36 (1H, s); 3.62 (2H, m); 3.23 (1H, m).

1. temperatureis heated
2. temperatureto reflux for 4 hours
3. concentrationthe reaction mixture is concentrated under reduced pressure
4. customCrystallization of the remanens from ethanol/water