[Br-].[F:2][CH2:3][CH2:4][CH2:5]P(C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.CC(C)([O-])C.[K+].[F:31][C:32]1[CH:33]=[C:34]([CH:39]2[CH2:44][CH2:43][C:42](=O)[CH2:41][CH2:40]2)[CH:35]=[C:36]([F:38])[CH:37]=1.O>C1COCC1>[F:31][C:32]1[CH:33]=[C:34]([CH:39]2[CH2:44][CH2:43][CH:42]([CH2:5][CH2:4][CH2:3][F:2])[CH2:41][CH2:40]2)[CH:35]=[C:36]([F:38])[CH:37]=1
THF in an amount of 100 ml was added to 12.5 g (31.0 mmol) of the 3-fluoropropyltriphenylphosphine bromide synthesized in the first step, and cooled down to 0° C. under nitrogen gas atmosphere. Solution of 3.4 g (31.0 mmol) of potassium-t-butoxide in 30 ml of THF was added thereto and stirred for 3 hours. To this reaction product was added dropwise a solution of 5.0 g (23.8 mmol) of the 4-(3,5-difluorophenyl)cyclohexanone synthesized in the second step in 50 ml of THF at 0° C., stirred at the temperature as it was for 1 hour, warmed up to room temperature, and then stirred for further 4 hours. Water in an amount of 100 ml was added to the reaction product, the product was extracted with ethyl acetate, the extract was washed with saturated aqueous sodium bicarbonate solution and water in turn, and then the organic layer was dried over magnesium sulfate. The solvent was distilled off under a reduced pressure and the residue was purified by column chromatography treatment using toluene as eluent. The purified product was subjected to hydrogenation in ethanol in the presence of 5% Pd/C catalyst. After termination of the reaction, the catalyst was filtered off, the ethanol was distilled off under a reduced pressure to obtain 1.3 g (5.1 mmol) of 4-(3,5-difluorophenyl)-1-(3-fluoropropyl)cyclohexane. Yield of this product from 4-(3,5-difluorophenyl)cyclohexanone was 21%.
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