Sodium hydride → 4-hydroxy-1-phenyl-3-(3-trifluoromethylphenylacetyl)-1,8-naphthyridin-2(1H)-one

In accordance with a process described in JP-61-246183A, 4-hydroxy-1-phenyl-1,8-naphthyridin-2(1H)-one was synthesized. To a suspension of the synthesized compound (953 mg, 4.0 mmol) in DMF (32 mL) was added sodium hydride (purity of about 60%, 352 mg, 8.8 mmol, 2.2 eq.), and the mixture was stirred at a room temperature for 35 minutes. Then, 3-trifluoromethylphenylacetyl chloride (4.8 mmol, 1.2 eq.) was added thereto with cooling in an ice bath, and the mixture was stirred at a room temperature for 1.5 hours. Thereafter, the resulting mixture was purified by a flash column chromatography to give 4-hydroxy-1-phenyl-3-(3-trifluoromethylphenylacetyl)-1,8-naphthyridin-2(1H)-one as a form of crystal (1.04 g, yield 61%).