[CH3:1][CH:2]([C:6]1[CH:7]=[C:8]([CH:14]=[CH:15][C:16]=1[OH:17])[C:9]([O:11]CC)=[O:10])[C:3]([CH3:5])=[CH2:4].[OH-].[K+]>CO.O>[CH3:1][CH:2]([C:6]1[CH:7]=[C:8]([CH:14]=[CH:15][C:16]=1[OH:17])[C:9]([OH:11])=[O:10])[C:3]([CH3:5])=[CH2:4]Ethyl 3-(1,2-dimethyl-allyl)-4-hydroxy-benzoate (600 mg, 2.56 mmol) was dissolved in methanol (20 ml), a solution of potassium hydroxide (560 mg, 10.0 mmol) in water (10 ml) was added and the mixture was stirred and held at reflux for 16 hours. Upon cooling the methanol was removed in vacuo and the solution acidified to pH 2 or below by the addition of 2M hydrochloric acid. The solution was extracted with dichloromethane, the organic layer was separated and the solvent was removed in vacuo to afford 3-(1,2-dimethyl-allyl)-4-hydroxy-benzoic acid (270 mg, 51%) as a colourless gum. 1H NMR (DMSO-d6) 12.38 (1H, br s), 10.22 (1H, br s), 7.63 (2H, m), 6.88 (1H, d), 4.90 (1H, s), 4.87 (1H, s), 3.75 (1H, q), 1.60 (3H, s), 1.28 (3H, d). MS: [M−H]+ 205.
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