Chloroacetonitrile → 1-Cyanomethyl-3-(2,6-difluorophenyl)pyrazole

3.0 g of 3-(2,6-difluorophenyl)pyrazole was dissolved in 20 ml of acetonitrile, and 2.52 g of chloroacetonitrile and 4.61 g of potassium carbonate were added thereto at room temperature, and heated under reflux for 5 hours. After acetonitrile was distilled off under reduced pressure, ethyl acetate was added to the residue, which was then washed with a small amount of water. The organic layer was dried over sodium sulfate, and the solvent was distilled off under reduced pressure. The residual product was recrystallized from a mixed solvent of isopropylether and diethyl ether to obtain 1.74 g of l-cyanomethyl-3-(2,6-difluorophenyl)pyrazole. 2) A solution of 0.5 g of 1-cyanomethyl-3-(2,6-difluorophenyl)pyrazole dissolved in 10 ml of THF was dropwise added to a suspension of 0.15 g of 55% sodium hydride in 10 ml of THF, at; 50° C. After the resulting product was stirred for 30 minutes, a solution of 0.67 g of 1-(1-methyl-3,5-dichloropyrazole-4-carbonyl)pyrazole dissolved in 10 ml of THF was dropwise added thereto at 50° C. and then stirred overnight at room temperature. The reaction mixture was poured into water, then extracted with ethyl acetate and washed with a small amount of water. The resulting product was dried over sodium sulfate, and the solvent was distilled off under reduced pressure. The residual product was recrystallized from a mixed solvent of isopropyl ether/ethyl acetate=3/1 to obtain 0.52 g of 2-(3-(2,6-difluorophenyl)pyrazol-1-yl)-3-(1-methyl-3,5-dichloropyrazol-4-yl)-3-hydroxyacrylonitrile.