Ethyl 3-(pyridin-2-yl)propionate (0.717 g, 2.0 eq., prepared in Synthetic Example 4) was dissolved in dry THF. To the solution was added LDA (2 ml of 2M solution, 2.0 eq.) at −78° C. or below in a methanol-dry ice bath under nitrogen atmosphere while stirring and the mixture was stirred for 1 hour. Next, to the reaction mixture was added dropwise a solution of 2-(3-nitrophenylamino)nicotinaldehyde (486 mg, 1.0 eq., prepared according to the procedure of Example 3 in JP, A, 62-228076 (1987)) in THF and the resultant mixture was stirred for 2 hours at −78° C. and then continued to stir for 24 hours until it reached room temperature. The reaction mixture was treated with water, and extracted with methylene chloride. The organic layer was dried, and evaporated. To the residue was added ethyl acetate to form crystals. The resulting crude crystals were subjected to recrystallization from DMF to give 1-(3-nitrophenyl)-3-(pyridin-2-ylmethyl)-1,8-naphthyridin-2(1H)-one, mp 229 to 231° C./DMF (yield 67%).
