反应详情

A sample of 15.0 g (0.0612 mol) of 6-allyl-7-hydroxy-8-methoxy-4-methylcoumarin was treated with 30 ml of conc. sulfuric acid at 25°. After 10 min, the dark mixture was diluted with 400 ml of ice water and extracted three times with methylene chloride/methanol, 4:1. The organic phases were dried and evaporated; the residue was filtered through 250 g silica, diluting with ethyl acetate/benzene, 1:4 to afford pure 2,5-dimethyl-9-methoxy-2,3-dihydro-7H-furo[3,2-g][1]-benzopyran-7-one, m.p. 113°-115°, as a white crystalline solid. Recrystallization from ethanol gave an analytical sample, m.p. 114°-115°.

1. extractionextracted three times with methylene chloride/methanol, 4:1
2. customThe organic phases were dried
3. customevaporated
4. filtrationthe residue was filtered through 250 g silica
5. additiondiluting with ethyl acetate/benzene, 1:4