反应详情

Sodium metal (0.36 g) was dissolved in dry ethanol (30 ml) then treated with hydroxylamine hydrochloride (1.12 g). A solution of 7-bromo-4-hydroxy-2H-chromen-2-one (Intermediate 31) (1.3 g) in dry ethanol (30 ml) was added and the mixture was stirred at reflux under nitrogen for 3.5 h. On cooling the mixture was added to 2M aqueous sodium bicarbonate (100 ml). Water (100 ml) and dichloromethane (100 ml) were added, the phases were separated and the aqueous layer was washed with more dichloromethane (75 ml). The aqueous layer was acidified by the cautious addition of 2N hydrochloric acid to yield a precipitate which was collected by filtration and dried to give the title compound as a white solid (1.06 g).

1. temperatureat reflux under nitrogen for 3.5 h
2. temperatureOn cooling the mixture
3. customthe phases were separated
4. washthe aqueous layer was washed with more dichloromethane (75 ml)
5. additionThe aqueous layer was acidified by the cautious addition of 2N hydrochloric acid
6. customto yield a precipitate which
7. filtrationwas collected by filtration
8. customdried