Allyl bromide → 7-(Allyloxy)-4-methyl-2H-chromen-2-one

Reaction equation

[OH:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6]([CH3:13])=[CH:7][C:8](=[O:12])[O:9]2)=[CH:4][CH:3]=1.C([O-])([O-])=O.[K+].[K+].[CH2:20](Br)[CH:21]=[CH2:22]>CC(C)=O>[CH2:22]([O:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6]([CH3:13])=[CH:7][C:8](=[O:12])[O:9]2)=[CH:4][CH:3]=1)[CH:21]=[CH2:20]

Participants

Procedure

7-Hydroxy-4-methylcoumarin (70.00 g, 0.397 mol), anhydrous K2CO3 (140 g, 1.01 mol), and allyl bromide (100 ml, 1.15 mol) were added to 2.0 L of reagent grade acetone. The milky mixture was refluxed for sixteen hours with overhead stirring, allowed to cool to room temperature, and filtered. Solids were washed once with reagent grade acetone (150 ml.), the filtrate and wash combined, and the resulting combined filtrate concentrated to dryness with a rotary evaporator to obtain 7-allyloxy-4-methylcoumarin (84.2 g, 98% yield). The crude product melted at 100.0°-101.5° C. (lit. 1 101° C.), showed only one spot in TLC, and was used in the next step.