反应详情

6-Butoxy-4-oxo-4H-chromen-3-carbaldehyde (VI-2; 5 g, 0.02 mol) prepared by the method described in Steps 1 and 2 of the Reference Example 2 and N-bromo succinicimide (4.4 g) were refluxed in carbon tetrachloride (350 ml) for 1 h while it was irradiated externally with 250W Matsushita Electric tungsuten lamp. The mixture was allowed to cool in an ice-bath and anhydrous methanol (6 ml) was added slowly and stirred for additional 30 min. The solvent was removed under reduced pressure and the residue was dissolved in ethyl acetate. The organic layer was washed successively with water, 1 M sodium hydroxide, water and brine and dried. The solvent was evaporated under reduced pressure to give 6.2 g of an orange solid. Recrystallization from 95% ethanol afforded 4.3 g (77%) of compound (VII-3) as pale yellow prisms. m.p. 88-89° C.

1. temperatureto cool in an ice-bath
2. customThe solvent was removed under reduced pressure
3. dissolutionthe residue was dissolved in ethyl acetate
4. washThe organic layer was washed successively with water, 1 M sodium hydroxide, water and brine
5. customdried
6. customThe solvent was evaporated under reduced pressure