反应详情

Smilagenone (657 g) was dissolved in tetrahydrofuran (4000 ml) and the solution purged with nitrogen and cooled to provide an internal temperature of ca. −10° C. L-Selectride® (2400 ml 1M in THF) was added over ca. 50 minutes and stirred for 90 minutes. A solution of citric acid (600 g) in water (2000 ml) was added slowly, maintaining the temperature below 0° C. The mixture was allowed to warm to ambient temperature and stirred for 30 minutes. The aqueous layer was separated and extracted with dichloromethane (2000 ml) and the layers separated. The aqueous layer was extracted with dichloromethane (1500 ml). The combined organic extracts were washed with water (4000 ml) and dried over MgSO4. The organic extracts were evaporated to dryness to yield smilagenin.

1. customthe solution purged with nitrogen
2. temperaturecooled
3. customto provide an internal temperature of ca. −10° C
4. temperaturemaintaining the temperature below 0° C
5. stirringstirred for 30 minutes
6. customThe aqueous layer was separated
7. extractionextracted with dichloromethane (2000 ml)
8. customthe layers separated
9. extractionThe aqueous layer was extracted with dichloromethane (1500 ml)
10. washThe combined organic extracts were washed with water (4000 ml)
11. dry with materialdried over MgSO4
12. customThe organic extracts were evaporated to dryness