反应详情

Cholestan-3-one (100 mg) was dissolved in chlorobenzene (5 ml), benzeneseleninic anhydride (188 mg, 2 equiv.) added and the solution heated to reflux with stirring under nitrogen in the dark. After 3 hours tlc showed almost complete reaction. The mixture was allowed to cool before filtering down a short silica column, washing with petrol containing 10% methylene chloride followed by releasing the crude product by washing with methanol. On evaporation an oil (107.1 mg) was obtained which crystallised on cooling in cardice. mp. 50°-57° C. Plc of the resulting impure product yielded 63.3 mg (63%) of cholesta-1,4-dien-3-one mp. 110°-112° C. (literature melting point 112° C.). λmax. 242 nm (ε 14500) (literature U.V. absorption 242 nm (ε 15000)). I.R. spectrum identical to previously prepared pure samples. The results of several runs are tabulated below:

1. temperaturethe solution heated
2. temperatureto reflux
3. customreaction
4. temperatureto cool
5. filtrationbefore filtering down a short silica column
6. washwashing with petrol containing 10% methylene chloride
7. washby washing with methanol
8. customOn evaporation an oil (107.1 mg)
9. customwas obtained which
10. customcrystallised
11. temperatureon cooling in cardice