[CH3:1][C:2]1[C:11]2[C:6](=[C:7]([CH3:13])[C:8]([OH:12])=[CH:9][CH:10]=2)[O:5][C:4](=[O:14])[CH:3]=1.CI.[C:17](=O)([O-])[O-].[K+].[K+]>CC(C)=O.[OH-].[Na+]>[CH3:1][C:2]1[C:11]2[C:6](=[C:7]([CH3:13])[C:8]([O:12][CH3:17])=[CH:9][CH:10]=2)[O:5][C:4](=[O:14])[CH:3]=1A solution of 4,8-dimethyl-7-hydroxycoumarin (0.190 g, 1.00 mmol) and methyl iodide (0.180 g, 1.30 mmol) in 50 ml of dry acetone was heated at reflux in the presence of 0.5 g of potassium carbonate for 14 hours. The solution was then cooled and filtered. The filtrate was evaporated under reduced pressure to yield a beige solid. The beige solid was taken up in 20% sodium hydroxide (aqueous) and collected by vacuum filtration. The crude product was recrystallized from methanol to yield shiny white crystals, m.p. 162°-164° C., 135 mg, 66% yield. 1H-NMR: 2.27 (s, 3H, C8 --CH3), 2.4 (d, 3H, C4 --CH3, J=1.2 Hz), 3.9 (s, 3H, OCH3), 6.1 (q, 1H, C3 --H, J=1.2 Hz), 6.8-6.9 (d, 1H, C6 --H, J=8.8 Hz), 7.4- 7.5 (d, 1H, C5 --H, J=8.8 Hz).
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