反应详情

15.9 g hydrazine hydrochloride and 18.4 ml hydrazine hydrate are added under stirring to 22.5 g of the product of step (a) in 20 ml n-propanol and the obtained reaction mixture is heated under reflux for 5 hours. The mixture is concentrated, treated with 500 ml H2O, filtered and washed with H2O (fraction A). The mother liquor is extracted with ethyl acetate and the extract evaporated. To the residue (7.5 g) are added 100 ml n-propanol and 20 ml triethylamine and the mixture is stirred and heated at reflux. The reaction is followed by thin layer chromatography. After approximately 15 hours when all of the β-product is converted into the 8α-product, H2O is added and the mixture is filtered. The filter cake is combined with fraction A and recrystallized twice from hot ethanol to afford the heading compound, m.p. 235°-240°, which is the pure α-isomer by NMR.

1. customthe obtained reaction mixture
2. temperatureis heated
3. temperatureunder reflux for 5 hours
4. concentrationThe mixture is concentrated
5. additiontreated with 500 ml H2O
6. filtrationfiltered
7. washwashed with H2O (fraction A)
8. extractionThe mother liquor is extracted with ethyl acetate
9. customthe extract evaporated
10. additionTo the residue (7.5 g) are added 100 ml n-propanol and 20 ml triethylamine
11. temperatureheated
12. temperatureat reflux
13. additionis added
14. filtrationthe mixture is filtered
15. customrecrystallized twice from hot ethanol
16. customto afford the heading compound, m.p. 235°-240°, which