After adding 1.16 g of 2-tert-butoxy-6-vinylpyrazine, 860 mg of 4-(2-chlorophenoxymethyl)piperidine hydrochloride and 0.43 g of anhydrous potassium carbonate to 10 ml of N,N-dimethylformamide, the mixture was stirred for 2 days at 100° C. Ice water was added to the reaction mixture and extraction was performed with ethyl acetate. The organic layer was washed with water and saturated brine in that order and dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was purified by NH silica gel column chromatography (solvent: n-hexane/ethyl acetate) to obtain the title compound (145 mg, 11% yield).
