The compound (51) (9.7 g), p-toluenesulfonic acid (0.15 g) and toluene (200 ml) were mixed, and the mixture was heated under reflux for 2 hours while water being distilled was removed. The reaction mixture was cooled to 30° C., and then water (200 ml) and toluene (300 ml) were added thereto and mixed. The mixture was then allowed to stand until it had separated into two phases of organic and aqueous phases, and extraction into an organic phase was carried out. The organic phase obtained was fractionated, washed sequentially with a saturated aqueous solution of sodium hydrogencarbonate and water, and then dried over anhydrous magnesium sulfate. The solution obtained was purified with a fractional operation by means of column chromatography using a mixed solvent of heptane and toluene (heptane:toluene=2:3 by volume) as the eluent and silica gel as the stationary phase powder. The solvent was distilled off, and the residue obtained was purified with a fractional operation by means of column chromatography using toluene as the eluent and silica gel as the stationary phase powder. The product was further purified by means of recrystallization from a mixed solvent of Solmix A-11 and ethyl acetate (Solmix A-11:ethyl acetate=2:1 by volume) and dried, giving 4.7 g of 1-(4-(2,3-difluoro-4-(4-pentylcyclohexyl)phenyl)cyclohex-3-enyl)-4-ethoxy-2,3-difluorobenzene (No. 12). The yield based on the compound (10) was 49.8%.
