[CH3:1][C:2]1[C:7]([CH3:8])=[CH:6][C:5]([CH3:9])=[C:4]([CH2:10][C:11]([CH3:13])=[CH2:12])[C:3]=1[OH:14].O.C1(C)C=CC(S(O)(=O)=O)=CC=1.[OH-].[Na+]>C1(C)C=CC=CC=1>[CH3:12][C:11]1([CH3:13])[CH2:10][C:4]2[C:5]([CH3:9])=[CH:6][C:7]([CH3:8])=[C:2]([CH3:1])[C:3]=2[O:14]1A mixture of 2,3,5-trimethyl-6-(2-methylprop-2-en-1-yl)phenol (13.0 g, 68.3 mmol) synthesized in Reference Example 2, p-toluenesulfonic acid monohydrate (1.30 g, 6.83 mmol) and toluene (130 mL) was stirred under heated reflux for 1.5 hours. After cooled to room temperature, the reaction solution was distributed by addition of 1N sodium hydroxide aqueous solution. The organic layer was washed with 1N sodium hydroxide aqueous solution and saturated saline, and then dried using anhydrous magnesium sulfate. The solvent was removed under reduced pressure, and the obtained residue was purified by basic silica gel chromatography (hexane-ethyl acetate 49:1 to 24:1) to give 11.1 g of the title compound (yield: 85%).
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