At room temperature, 5-bromo-1,2-dihydropyridin-2-one (1.04 g, 6 mmol) was dissolved in DMF (12 mL), sodium hydride (60% dispersion in mineral oil, 960 mg, 24 mmol) was added and the reaction mixture was stirred for 30 minutes. Subsequently, ethyl iodide (0.58 mL, 7.2 mmol) was slowly added to the reaction system and stirring was continued overnight at room temperature. This operation was repeated twice to ensure complete reaction. Upon completion of the reaction, the mixture was diluted with water and dichloromethane (DCM). The organic layer was separated, washed sequentially with saturated sodium bicarbonate solution and brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. Finally, the residue was purified by silica gel column chromatography (eluent: DCM/MeOH 98/2) to afford the target compound 5-bromo-1-ethylpyridin-2(1H)-one (532 mg, 2.63 mmol, 44% yield).
