Into a 100 ml three-necked flask, 2.86 g of cuprous iodide, 4.33 g (0.012 mol) of (E)-3,4-difluoro-1-(4-propylphenyl)-4-(4-bromophenyl)-3-buten-1-yne obtained in Example 4 and 30 ml of dry THF were charged under an argon atmosphere, followed by stirring at room temperature. Then, 1.42 g of n-butylamine and 1.53 g of p-toluylacetylene were added thereto. Then, 10 ml of a dry THF solution containing 0.69 g of (Ph3P)4Pd was added thereto, and the mixture was stirred at room temperature for 2 hours. After an addition of 30 ml of a saturated NaHCO3 aqueous solution, the mixture was subjected to liquid separation, and then extracted with methylene chloride. The solvent was distilled off, and the residue was purified by silica gel column chromatography to obtain 3.09 g (yield: 65%) of (E)-3,4-difluoro-1-(4-propylphenyl)-4-[4-(2-p-toluylethynyl)phenyl]-3-buten-1-yne.
