55% Sodium hydride (1.41 g, 32.1 mmol) was suspended in tetrahydrofuran (300 ml). To the suspension was added 5-(4-chlorophenyl)-4-(pyridin-4-yl)pyrazole (8.21 g, 32.1 mmol), and the resulting mixture was stirred at room temperature for 1 hour. To the resulting mixture was added (2-trimethylsilylethoxy)methyl chloride (5.68 ml, 32.1 mmol) dropwise under ice cooling, and the mixture was stirred at room temperature overnight. At the end of this time, water was added to the mixture and the mixture was extracted with ethyl acetate. The organic layer was washed with water, dried over anhydrous sodium sulfate and the solvent was removed by distillation under reduced pressure. The residue was purified by column chromatography through silica gel (eluent, hexane:ethyl acetate=3:1), to give the title compound (11.12 g) as a pale brown oil (yield 90%).
