To a tetrahydrofuran solution (2 ml) of tert-butyl 4-(7-chloro-2-oxo-3,4-dihydro-1,5-naphthyridin-1(2H)-yl)piperidine-1-carboxylate (Reference Example 9-3) (438 mg) was added dropwise at −20° C. a hexane solution (1.0 M, 1.32 ml) of lithium hexamethyldisilazide over 10 minutes. After the reaction solution was stirred for 30 minutes, was added dropwise a tetrahydrofuran solution of 1-(2-bromoethoxymethyl)-4-methoxybenzene (Journal of Medicinal Chemistry, 2007, 50(26), 6580-6595)(324 mg) and 1,3-dimethyltetrahydropyrimidin-2(1H)-one (315 mg). The reaction solution was brought to 0° C. over 30 minutes, and then stirred for 90 minutes. Water was added to the reaction solution, and extracted with ethyl acetate. The organic layer was washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to afford tert-butyl 4-[7-chloro-3-{2-[(4-methoxybenzyl)oxy]ethyl}-2-oxo-3,4-dihydro-1,5-naphthyridin-1(2H)-yl]piperidine-1-carboxylate (189 mg).
