1360599-43-4

5-Methylquinoxaline (9.50 g, 65.97 mmol) was dissolved in acetonitrile (80 mL) at room temperature, followed by addition of N-bromosuccinimide (27.00 g, 151.74 mmol). The reaction mixture was stirred at 60 °C for 16 hours. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently concentrated under reduced pressure. To the concentrated residue was added ethyl acetate (500 mL) for dilution. Insoluble solids were removed by filtration and the filtrate was sequentially washed with saturated brine and dried with anhydrous sodium sulfate. Finally, the solvent was removed under reduced pressure to afford the target compound 5-bromo-8-methylquinoxaline as a brown solid (6.00 g, 41% yield). Mass spectrometry result: m/z = 222.9 [M + H]+.

[1] Patent: WO2017/106607, 2017, A1. Location in patent: Paragraph 00217; 00218
[2] Patent: WO2018/31434, 2018, A1. Location in patent: Paragraph 00198; 00202