反应详情

500 mg of (25R)-5a-spirost-14-ene-3,12-dione is dissolved in 15 ml of tetrahydrofuran and mixed with 453 mg (1.1 eq) of pyridinium bromide-perbromide, dissolved in 25 ml of tetrahydrofuran. After two and one half hours of stirring at room temperature, the reaction is arrested by adding 20 ml of water and the mixture is extracted with dichloromethane. The organic phase is washed with sodium chloride solution, dried on magnesium sulfate, the solvent is removed and the residue is chromatographed with petroleum ether/ethyl acetate (4:1) on silica gel. The combined fractions are concentrated by evaporation and stirred overnight in 10 ml of methanol. After filtration and evaporation of the solvent, there is obtained:

1. extractionthe mixture is extracted with dichloromethane
2. washThe organic phase is washed with sodium chloride solution
3. customdried on magnesium sulfate
4. customthe solvent is removed
5. customthe residue is chromatographed with petroleum ether/ethyl acetate (4:1) on silica gel
6. concentrationThe combined fractions are concentrated by evaporation
7. stirringstirred overnight in 10 ml of methanol
8. filtrationAfter filtration and evaporation of the solvent
9. customthere is obtained