反应详情

To a stirred solution of 1H-quinoxalin-2-one (50 g, 342.5 mmol) in glacial acetic acid (2500 mL) was added bromine (54.7 g, 342.5 mmol in 120 mL acetic acid) over a period of 1.5 h at rt. After 18 h stirring, the mixture was slowly poured into 2000 mL water and stirred for 1 h at rt. The precipitate was filtered and the residue was washed with water and dried to give 7-bromo-1H-quinoxalin-2-one as an off-white solid (51 g, 66%): 1H-NMR (300 MHz, d6-DMSO): δ=12.42 (1H, s), 8.19 (1H, s), 7.75 (1H, d), 7.44 (2H, m) ppm.

1. stirringstirred for 1 h at rt
2. filtrationThe precipitate was filtered
3. washthe residue was washed with water
4. customdried