反应详情

This protocol was modified to synthesis 5β exclusively. Briefly, compound 2 (1.0 g, 3.03 mmol) and alcohol 4 (1.60 g, 9.11 mmol) were dissolved in anhydrous DCM (20 mL), followed by addition of dried 4 A° MS (0.4 g) and reaction mixture stirred at room temperature for 20 minutes under N2. CSA (camphor sulphonic acid, 0.615 g, 9.0 mL, 9.1 mmol) was added at room temperature and 8 hours, followed by heating to 45° C. for 24 hours. The reaction mixture was cooled to room temperature, neutralized with Et3N (0.2 mL, pH 7.5), diluted with DCM (100 mL) and extracted using saturated NaHCO3 solution. The organic layer was washed with water, brine and dried over Na2SO4. Solvents were evaporated under reduced pressure and the residue purified by silica gel column chromatography using DCM:EtOAc:MeOH (8.0:1.5:0.5) to obtain compound 5β (1.15 g, 85%). The spectral data matched with above compound 5β.

1. customThis protocol was modified to synthesis 5β exclusively
2. additionfollowed by addition
3. customof dried
4. custom4 A° MS (0.4 g) and reaction mixture
5. temperatureby heating to 45° C. for 24 hours
6. temperatureThe reaction mixture was cooled to room temperature
7. extractionextracted
8. washThe organic layer was washed with water, brine
9. dry with materialdried over Na2SO4
10. customSolvents were evaporated under reduced pressure
11. customthe residue purified by silica gel column chromatography
12. customto obtain compound 5β (1.15 g, 85%)