反应详情

温度

-78 °C

Under argon, 3.10 g (6.94 mmol) of 7-cyclopentyl-5-methoxy-2,2-dimethyl-6-[4-(trifluoro-methyl)benzoyl]-2,3-dihydro-4H-chromen-4-one (Example 8A) are dissolved in 30 ml of abs. dichloromethane. The mixture is cooled to −78° C., 6.25 ml (6.25 mmol) of boron tribromide (1 M in dichloromethane) are added and the yellowish solution is stirred at −78° C. After 1.5 h, another 6.25 ml (6.25 mmol) of boron tribromide (1 M in dichloromethane) are added, and stirring of the mixture is continued at −78° C. After 30 min, another 1.39 ml (1.39 mmol) of boron tribromide (1 M in dichloromethane) are added. After 30 min, 100 ml of water are added and the mixture is stirred for 30 min and allowed to warm to room temperature. The mixture is then extracted repeatedly with ethyl acetate. The combined organic phases are washed once with saturated sodium bicarbonate solution and once with saturated sodium chloride solution, dried over sodium sulfate, filtered and concentrated. The crude product is purified on a silica gel column (mobile phase: cyclohexane/ethyl acetate 25:1). This gives 1.85 g (62% of theory) of the title compound.

1. stirringstirring of the mixture
2. customis continued at −78° C
3. waitAfter 30 min
4. waitAfter 30 min
5. stirringthe mixture is stirred for 30 min
6. temperatureto warm to room temperature
7. extractionThe mixture is then extracted repeatedly with ethyl acetate
8. washThe combined organic phases are washed once with saturated sodium bicarbonate solution and once with saturated sodium chloride solution
9. dry with materialdried over sodium sulfate
10. filtrationfiltered
11. concentrationconcentrated
12. customThe crude product is purified on a silica gel column (mobile phase: cyclohexane/ethyl acetate 25:1)