To a solution of rac-(1R,2R,4S)-bicyclo[2.2.1]heptan-2-ol (1.12 g) in tetrahydrofuran (10 mL) was added 60% sodium hydride (400 mg) under ice-cooling, and the mixture was stirred at room temperature for 10 minutes. The reaction mixture was further stirred at an external temperature of 60° C. for 30 minutes, and then ice-cooled, and a mixture of methyl 2-chloro-4-(trifluoromethyl)pyrimidine-5-carboxylate (481 mg) and tetrahydrofuran (2 mL) was added thereto, followed by stirring at room temperature for 3 hours. To the reaction mixture were added water and saturated brine, followed by extraction with ethyl acetate. The obtained organic layer was washed with saturated brine and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography (eluent: hexane-ethyl acetate=100:0 to 97:3) to obtain a mixture (351 mg) of rac-(1R,2R,4S)-bicyclo[2.2.1]hept-2-yl2-[(1R,2R,4S)-bicyclo[2.2.1]hept-2-yloxy]-4-(trifluoromethyl)pyrimidine-5-carboxylate and rac-(1R,2R,4S)-bicyclo[2.2.1]hept-2-yl2-[(1S,2S,4R)-bicyclo[2.2.1]hept-2-yloxy]-4-(trifluoromethyl)pyrimidine-5-carboxylate as a colorless oily substance.
