To a solution of 1-(3-trifluoromethylphenyl)dihydropyrimidin-2,4(1H,3H)-dione (prepared in Reference Example 96) (770.0 mg) in acetic acid (10.0 ml) was added bromine (0.18 ml) and the resulting mixture was stirred with heating under reflux for two hours. To the reaction mixture were added water (30 ml) and 10% aqueous sodium thiosulfate solution (5 ml) and the precipitated solids were collected by filtration with water to afford a mixture containing 5-bromo-1-(3-trifluoromethylphenyl)pyrimidin-2,4(1H,3H)-dione, 5,5-dibromo-1-(3-trifluoromethylphenyl)dihydropyrimidin-2,4(1H,3H)-dione and 5-bromo-1-(3-trifluoromethylphenyl)dihydropyrimidin-2,4(1H,3H)-dione (800.0 mg). A solution of the resulting mixture (800.0 mg) and lithium chloride (122.3 mg) in N,N-dimethyl formamide (5.0 ml) was stirred at 120° C. for one and a half hours. To the reaction mixture was added water (20 ml) and the resulting mixture was extracted with ethyl acetate (20 ml×2), and the organic layer was washed with water (20 ml×2) and saturated saline (20 ml), dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane/ethyl acetate) to afford 5-bromo-1-(3-trifluoromethylphenyl)pyrimidin-2,4(1H,3H)-dione (473.1 mg) and 1-(3-trifluoromethylphenyl)pyrimidin-2,4(1H,3H)-dione (135.8 mg).
