[CH2:1]([O:8][C:9]1[CH:18]=[CH:17][C:12]([C:13]([O:15]C)=[O:14])=[CH:11][C:10]=1/[C:19](/[CH3:22])=[CH:20]\[CH3:21])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[OH-].[K+]>CO.O>[CH2:1]([O:8][C:9]1[CH:18]=[CH:17][C:12]([C:13]([OH:15])=[O:14])=[CH:11][C:10]=1/[C:19](/[CH3:22])=[CH:20]\[CH3:21])[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1Methyl(Z)-4-benzyloxy-3-(1-methyl-propenyl)-benzoate (592 mg, 2.0 mmol) was dissolved in methanol (20 ml), a solution of potassium hydroxide (336 mg, 6.0 mmol) in water (7 ml) was added and the mixture was stirred and held at reflux for 3 hours. Upon cooling the solvent was removed in vacuo and the mixture acidified to pH 2 or below by the addition of 2M hydrochloric acid. The mixture was extracted with dichloromethane, the organic layer was separated and the solvent removed in vacuo to afford (Z)-4-benzyloxy-3-(1-methyl-propenyl)-benzoic acid (460 mg, 82%) as a colourless solid. 1H NMR (DMSO-d6) 7.85 (1H, dd), 7.57 (1H, d), 7.40 (4H, m), 7.34 (1H, m), 7.18 (1H, d), 5.57 (1H, q), 5.21 (2H, s), 1.96 (3H, s), 1.40 (3H, d). MS: [M+H]+ 283.
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