Water → 2-Chloro-1-ethoxy-3-fluoro-4-(4-vinylcyclohexa-1-enyl)benzene

16.0 g of the compound (24), 0.3 g of p-toluenesulfonic acid and 80 mL of toluene were mixed, and the mixture was refluxed under heating for 1 hour while water distilled out was removed. After cooling the resulting reaction mixture to 25° C., 100 mL of water and 100 mL of toluene were added to and mixed with the reaction mixture. Thereafter, the mixture was separated into an organic layer and an aqueous layer by standing still, so as to attain extraction to the organic layer. The resulting organic layer was fractionated and washed with a 2N sodium hydroxide aqueous solution, a saturated sodium bicarbonate aqueous solution and water, followed by drying over anhydrous magnesium sulfate. Thereafter, the solvent was removed by distillation under reduced pressure to obtain a residue. The resulting residue was purified by silica gel column chromatography using a mixed solvent of heptane and toluene (heptane/toluene=2/1 by volume) as eluent, and then further purified by recrystallization from ethanol to obtain 5.11 g of 2-chloro-1-ethoxy-3-fluoro-4-(4-vinylcyclohexa-1-enyl)benzene (No. 286) in white color. The yield based on the compound (23) was 45.2%.