A mixed solution of N-{[6-bromo-1-(4-methoxybenzyl)-2-oxo-4-(trifluoromethyl)-1,4-dihydro-2H-3,1-benzoxazin-4-yl]methyl}-4-fluorobenzamide (100 mg, 0.176 mmol), tris(dibenzylideneacetone)dipalladium (8.0 mg, 0.008 mmol), xantphos (15.2 mg, 0.024 mmol), cesium carbonate (57.4 mg, 0.176 mmol) and 2-pyrrolidinone (26.8 μL, 0.352 mmol) in dioxane (0.5 mL) was stirred at 120° C. for 30 minutes under microwave irradiation. After the reaction solution was left to cool, the solution was diluted with ethyl acetate and the organic layer was separated. The organic layer was washed with water and saturated brine and then dried over magnesium sulfate. After the drying agent was removed by filtration, the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/hexane=1/1), whereby the objective compound (69 mg, 69%) was obtained as a yellow oily substance.
