7-Bromo-2(1H)-quinoxalinone (313.1 mg, 1.391 mmol) was dissolved in 0.15 M DMF solution (9.2 mL) and potassium carbonate (288.4 mg, 2.087 mmol) and iodomethane (95.5 μL, 1.530 mmol) were added sequentially. The reaction mixture was stirred at room temperature for 30 min. After completion of the reaction, the reaction mixture was diluted with water and extracted with ethyl acetate (2×). The organic phases were combined, washed sequentially with water (3×) and saturated saline (1×), dried over anhydrous sodium sulfate, filtered and concentrated. Purification by Biotage fast chromatography (eluent: hexane/ethyl acetate) afforded 7-bromo-1-methyl-1H-quinoxalin-2-one (87.6 mg, 0.366 mmol, 26.3% yield).1H NMR (400 MHz, (CD3)2SO) δ = 8.257 (s, 1H), 7.824 (s, 1H), 7.768-7.746 (d, 1H), 7.569-7.543 (dd, 1H), 3.591 (s, 3H).
