A mixture of 531 g (1170 mmol) of 2-(1,3-dioxane-2-yl)ethyltriphenylphosphonium bromide and 4.0 l of THF was cooled to −30° C. under a nitrogen gas stream with a refrigeration medium. To this mixture, 121 g (1080 mmol) of t-BuOK was added, followed by stirring for 1 hour. Furthermore, 1 l of a THF solution containing 200 g (899 mmol) of 4-(trans-4-propylcyclohexyl)cyclohexanone was added dropwise to the mixture, while the temperature was maintained at −30° C. or less. After the dropping, the reaction temperature was slowly raised to room temperature, and the solution was further stirred for 5 hours. Next, the reaction solution was filtered through Celite, and the solvent was then distilled off under reduced pressure. The resulting residue was purified through silica gel column chromatography (a developing solvent: a mixed solvent of toluene/ethyl acetate=9/1 (v/v)) to obtain 277 g of crude 2-(2-(4-(trans-4-propylcyclohexyl)cyclohexylidene)ethyl)-1,3-dioxane.
