反应详情

Compound 2 (230 mg, 0.571 mmol) obtained in Example 2 was dissolved in dichloromethane (6.0 mL), and O-allyl-2,2,2-trichloroacetimidate (130 μL, 0.857 mmol) and boron trifluoride—ethyl ether complex (36.1 μL, 0.286 mmol) were added thereto at 0° C., followed by stirring for 3 hours. Subsequently, O-allyl-2,2,2-trichloroacetimidate (43.3 μL, 0.286 mmol) and boron trifluoride—ethyl ether complex (18.1 μL, 0.143 mmol) were further added thereto, followed by stirring for 4 hours. A saturated aqueous sodium bicarbonate solution was added to the reaction mixture, followed by extraction with ethyl acetate twice. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to yield a residue. The residue was purified by silica gel column chromatography to obtain (3S,5S)-3-allyloxy-7-oxa-8-cholesten-6-one (145 mg, 57%).

1. customat 0° C.
2. stirringby stirring for 4 hours
3. extractionfollowed by extraction with ethyl acetate twice
4. washThe organic layer was washed with saturated brine
5. dry with materialdried over anhydrous magnesium sulfate
6. concentrationconcentrated under reduced pressure
7. customto yield a residue
8. customThe residue was purified by silica gel column chromatography