[CH3:1][O:2][C:3]1[CH:4]=[C:5]([OH:9])[CH:6]=[CH:7][CH:8]=1.S(=O)(=O)(O)O.[CH3:15][C:16]([CH3:22])=[CH:17][C:18](OC)=[O:19]>C(OCC)(=O)C>[CH3:1][O:2][C:3]1[CH:4]=[C:5]2[C:6]([C:16]([CH3:22])([CH3:15])[CH2:17][C:18](=[O:19])[O:9]2)=[CH:7][CH:8]=1A mixture of 3-methoxy-phenol (12 g, 96.5 mmol) and conc. sulfuric acid (0.5 ml) was heated at 130° C. with stirring, and methyl 3,3-dimethylacrylate (5.8 g, 51 mmol) was added. The mixture was stirred at 13° C. for 3 hours. After being cooled to ambient temperature, the organic layer was dissolved in ethyl acetate. The organic layer washed with brine, dried over sodium sulfate. After filtration to separate solvent and sodium sulfate, the solvent was removed under reduced pressure to give a residue, which was applied to a silica gel chromatography column and eluted with ethyl acetate/hexane= 1/9 to furnish 4.1 g (39% yield) of the title compound as a brown solid.
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