Imidazole 0.43 g and DBU 1.9 g were dissolved in 40 mL of THF. Under cooling with ice, 0.97 g of phenylacetyl chloride was dropped into the solution, followed by 20 minutes' stirring at room temperature. Then 40 mL of a THF solution containing 0.8 g of 5-amino-3-(4-fluorophenyl)-4-(4-pyrimidinyl)isoxazole was dropped into the system and stirred at room temperature for 6 hours. From the reaction solution the solvent was distilled off under reduced pressure and water was added to the residue, which was then extracted with ethyl acetate. The organic layer was dried over anhydrous magnesium sulfate and from which the solvent was distilled off under reduced pressure. Thus obtained residue was purified on 40 g silica gel column chromatography (eluent, chloroform:methanol=100:1) and washed with ether to provide 0.77 g of the title compound (yield: 66%) in the form of colorless crystal.
