Allyl bromide → Methyl 2-hydroxy-4-[(prop-2-en-1-yl)oxy]benzoate

Reaction equation

[CH3:1][O:2][C:3](=[O:12])[C:4]1[CH:9]=[CH:8][C:7]([OH:10])=[CH:6][C:5]=1[OH:11].C(=O)([O-])[O-].[K+].[K+].[CH2:19](Br)[CH:20]=[CH2:21]>CC(C)=O>[CH3:1][O:2][C:3](=[O:12])[C:4]1[CH:9]=[CH:8][C:7]([O:10][CH2:21][CH:20]=[CH2:19])=[CH:6][C:5]=1[OH:11]

Participants

Procedure

To a solution of 2,4-dihydroxy-benzoic acid methyl ester (12.254 g, 72.8 mmol) in acetone (120 mL) was added potassium carbonate (30.72 g, 222.3 mmol) and allyl bromide (7 mL, 80.9 mmol). The reaction mixture was heated at reflux for 5 hours, and then cooled to room temperature. It was partitioned between ethyl acetate and brine and the aqueous layer was extracted with ethyl acetate. The combined organics were washed with brine, dried over anhydrous magnesium sulfate and concentrated in vacuo. The residue was purified by flash chromatography using ethyl acetate/hexanes (4/96) to afford 4-allyloxy-2-hydroxy-benzoic acid methyl ester (10.952 g, 77%) as a yellow oil. 1H NMR (300 MHz, CDCl3); δ 10.95 (s, 1H), 7.72 (d, 2H), 6.45 (m, 2H), 6.02 (m, 1H), 5.35 (m, 2H), 4.55 (d, 2H), 3.90 (s, 3H).