Sodium hydride → 1-(4-methoxybenzyl)-7-bromo-1,5-naphthyridin-2(1H)-one

To a stirred solution of 7-bromo-1,5-naphthyridin-2(1H)-one (C-4) (29 g, 128.9 mmol, 1.0 eq) in DMF (200 mL) was added sodium hydride (60% in mineral oil, 7.73 g, 193.3 mmol, 1.5 eq) in portions at RT, the mixture was stirred at 30 to 40° C. for 1 h. 1-(Chloromethyl)-4-methoxybenzene (30.28 g, 193.3 mmol, 1.5 eq) was added dropwise. The resulting mixture was stirred at 30 to 40° C. overnight and quenched with water (500 mL) and extracted with ethyl acetate (5×200 mL). The combined organic layers were washed with brine, dried over Na2SO4 and filtered. The filtrate was concentrated in vacuo and the residue was purified by flash column chromatography on silica gel (10-50% ethyl acetate/petroether) to afford the desired product, 1-(4-methoxybenzyl)-7-bromo-1,5-naphthyridin-2(1H)-one (C-5) (20.2 g, 45.4% yield) as a white solid. 1H NMR (400 MHz, DMSO-d6) δ: 8.61 (s, 1H), 8.15 (s, 1H), 8.00 (d, J=10 Hz, 1H), 7.18 (d, J=8.4 Hz, 2H), 7.02 (d, J=9.6 Hz, 1H), 6.89 (d, J=8.8 Hz, 2H), 5.45 (s, 2H), 3.71 (s, 3H); ESI-MS m/z: 345.1 [M+H]+.