In a 100 mL-volume glass flask were placed 10.0 g (34.4 mmol.) of 4-(4-fluorophenyl)-2-hydroxy-6-isopropyl-5-methoxycarbonylpyrimidine, 5.22 g (58.5 mmol.) of triethylamine, and 34 mL of acetonitrile. The mixture in the flask was chilled to 0-5° C. in an ice bath. To the chilled mixture was slowly added 5.12 g (44.7 mmol.) of methanesulfonyl chloride, and the resulting mixture was subjected to reaction at 20-25° C. for 2 hours. After the reaction was complete, to the reaction mixture was added 60 mL of water. The aqueous reaction mixture was extracted with toluene and the toluene portion was separated. The toluene portion was washed with a saturated aqueous sodium chloride solution and dried over anhydrous magnesium sulfate. The dried mixture was filtered and concentrated under reduced pressure. The residue was crystallized from methanol, to give 11.3 g of 4-(4-fluorophenyl)-6-isopropyl-5-methoxycarbonyl-2-methanesulfonyloxypyrimidine as a colorless crystalline product having the below-mentioned characteristics. The yield was 89% (based on the amount of 4-(4-fluorophenyl)-2-hydroxy-6-isopropyl-5-methoxycarbonylpyrimidine).
