Ammonium Chloride → 4-(1,4-Dioxaspiro[4.5]decan-8-yl)-1-(4-butoxy-2,3-difluorophenyl)-cyclohexanol

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Reaction Conditions

Reaction Steps

3-Butoxy-1,2-difluorobenzene (s-4) (10.0 g) and THF (200 ml) were put in a reaction vessel and were cooled to −74° C. under an atmosphere of nitrogen. sec-Butyllithium (a 1.00 M solution in n-hexane and cyclohexane; 64.0 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, 4-(1,4-dioxaspiro[4.5]decan-8-yl)-cyclohexanone (s-5) (12.8 g) in a THF (50 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 mixture was poured into a vessel containing an aqueous solution of ammonium chloride (3%; 100 ml) and ethyl acetate (100 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 to give 4-(1,4-dioxaspiro[4.5]decan-8-yl)-1-(4-butoxy-2,3-difluorophenyl)-cyclohexanol. p-Toluenesulfonic acid (0.68 g) and toluene (200 ml) were mixed with this 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 (200 ml) and toluene (200 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. Pd/C (0.3 g) was added to the product 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 recrystallization from a mixed solvent of THF/heptane (1/9 by volume) to give 8-[4-(4-butoxy-2,3-difluorophenyl)-cyclohexenyl]-1,4-dioxaspiro[4.5]decane (s-6) (7.7 g). The yield based on the compound (s-4) was 35.2%.

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