[OH:1][C:2]1[CH:11]=[C:10](O)[C:9]([CH:13]([CH3:15])[CH3:14])=[CH:8][C:3]=1[C:4]([O:6][CH3:7])=[O:5].[C:16](=O)([O-])[O-].[K+].[K+].S([O:27][CH3:28])(OC)(=O)=O>C(#N)C>[CH:13]([C:9]1[C:10]([O:27][CH3:28])=[CH:11][C:2]([O:1][CH3:16])=[C:3]([CH:8]=1)[C:4]([O:6][CH3:7])=[O:5])([CH3:15])[CH3:14]A mixture of methyl 2,4-dihydroxy-5-isopropylbenzoate (420 mg, 2.0 mmol) and anhydrous potassium carbonate (662 mg, 4.8 mmol) in acetonitrile (10 ml) was treated with dimethyl sulphate (0.4 ml, 4.2 mmol) and the mixture was stirred at room temperature for 16 hours and then held at reflux for 6 hours. Upon cooling to room temperature the solvent was removed in vacuo and the residue acidified by the addition of 2M hydrochloric acid (10 ml). The solid material was collected by suction filtration, rinsed with water (2×10 ml) and sucked dry under reduced pressure to afford methyl 5-isopropyl-2,4-dimethoxybenzoate (350 mg, 74%) as a colourless solid. 1H NMR (DMSO-d6) 7.53 (1H, s), 6.67 (1H, s), 3.92 (3H, s), 3.86 (3H, s), 3.75 (3H, s), 3.13 (1H, m), 1.14 (6H, d). MS: [M+Na]+ 261.
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