3-Hexyloxy-1,2-difluorobenzene (s-11) (100 g) and THF (1000 ml) were put in a reaction vessel under an atmosphere of nitrogen and cooled to −74° C. sec-Butyllithium (a 1.00 M solution in n-hexane and cyclohexane; 500 ml) was added dropwide thereto in the temperature range of −74° C. to −70° C., and the stirring was continued for another 2 hours. Then, 1,4-dioxaspiro[4.5]decan-8-one (s-12) (72.9 g) in a THF (200 ml) solution was added dropwise thereto in the temperature range of −75° C. to −70° C., and the stirring was continued for another 8 hours while the mixture was allowed to come to 25° C. The reaction mixture was poured into a vessel containing an aqueous solution of ammonium chloride (3%; 500 ml) and ethyl acetate (500 ml), and mixed with them. The mixture was then allowed to stand until it had separated into organic and aqueous phases, and the extraction was carried out. The combined organic phase was washed successively with water, a saturated aqueous solution of sodium hydrogencarbonate and water, and dried over anhydrous magnesium sulfate. Then, the solvent was distilled off under the reduced pressure to give 8-(4-butoxy-2,3-difluorophenyl)-1,4-dioxaspiro[4.5]decan-8-ol. p-Toluenesulfonic acid (4.1 g) and toluene (300 ml) were added to the compound and the mixture was heated to reflux for 2 hours, while distilled water was removed. After the reaction mixture had been cooled to 30° C., water (500 ml) and toluene (500 ml) were added to the mixture, and mixed with it. The mixture was then allowed to stand until it had separated into two phases of organic and aqueous phases, and the extraction was carried out. The combined organic phase was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and water, and dried over anhydrous magnesium sulfate. The resulting solution was purified by column chromatography using silica gel as a stationary phase powder and toluene as an eluent. The product was dissolved in a mixed solvent of toluene (200 ml) and Solmix A-11 (200 ml), Pd/C (1.4 g) was added thereto and the mixture was stirred at room temperature under an atmosphere of hydrogen until hydrogen absorption had ceased. After the completion of the reaction, Pd/C was removed and the solvent was distilled off. The resulting residue was purified by column chromatography using silica gel as a stationary phase powder and toluene as an eluent, and then by recrystallization from Solmix A-11 to give 8-(4-hexyloxy-2,3-difluorophenyl)-1,4-dioxaspiro [4.5]decane (s-13) (127.4 g). The yield based on the compound (s-11) was 73.6%.
