Sulfuric Acid → 2-methyl-9-methoxy-2,3-dihydro-7H-furo[3,2-g][1]benzopyran-7-one
Reaction equation
[CH2:1]([C:4]1[CH:5]=[C:6]2[C:11](=[C:12]([O:15][CH3:16])[C:13]=1[OH:14])[O:10][C:9](=[O:17])[CH:8]=[CH:7]2)[CH:2]=[CH2:3].S(=O)(=O)(O)O>>[CH3:3][CH:2]1[O:14][C:13]2=[C:12]([O:15][CH3:16])[C:11]3[O:10][C:9](=[O:17])[CH:8]=[CH:7][C:6]=3[CH:5]=[C:4]2[CH2:1]1Participants
3
Procedure
A sample of 1.0 g. (4.31 mmoles) of 6-allyl-7-hydroxy-8-methoxycoumarin was dissolved in 20 ml. of conc. sulfuric acid at 25°. After 10 min, the solution was diluted with ice water. The mixture was extracted with methylene chloride, dried over sodium sulfate, and evaporated to yield 90 g. of residue. This was filtered through a column of silica gel, eluting with benzene/ethyl acetate, 4:1, to afford, upon evaporation of the filtrate, pure 2-methyl-9-methoxy-2,3-dihydro-7H-furo[3,2-g][1]benzopyran-7-one as a white solid. Recrystallization from ethanol yielded an analytical sample, mp 115°-116°.
Workup
- customat 25°
- extractionThe mixture was extracted with methylene chloride