4-Pentyl-(2,3-difluorophenyl)cyclohexane (10) (5.0 g) and THF (100 ml) were put in a reaction vessel under a nitrogen atmosphere, and cooled to −74° C. sec-Butyllithium (1.00 M, in a n-hexane and cyclohexane solution; 23.0 ml) was added dropwise thereto in the temperature range of −74° C. to −70° C., and the mixture was stirred for another 2 hours. 1-(4-Ethoxy-2,3-difluorophenyl)-cyclohexan-4-one (50) (4.8 g) dissolved in THF (150 ml) was slowly added dropwise thereto in the temperature range of −74° C. to −70° C., and the stirring was continued for another 8 hours while the mixture was allowed to return to 25° C. The reaction mixture obtained was poured into a vessel containing an aqueous solution of ammonium chloride (3%; 500 ml) and toluene (300 ml) which had been cooled to 0° C., and mixed. The mixture was then allowed to stand until it had separated into organic and aqueous phases, and extraction into an organic phase was carried out. The organic phase obtained was fractionated, washed sequentially with water, a saturated aqueous solution of sodium hydrogencarbonate and water, and then dried over anhydrous magnesium sulfate. Then, the solvent was distilled off under reduced pressure, giving 9.7 g of 1-(2,3-difluoro-4-(4-pentylcyclohexyl)phenyl)-4-(4-ethoxy-2,3-difluorophenyl)cyclohexanol (51). The compound (51) obtained was a yellow solid.
