Phosphorus oxychloride → 7-Bromo-2-chloroquinoxaline

Participants

Reaction Steps

300 mL POCl3 and 1 mL DMF were added to 7-bromo-1H-quinoxalin-2-one (30 g, 133.0 mmol) under stirring. The mixture was heated to reflux over a period of 1 h and refluxed for 2 h. After cooling to rt, the mixture was slowly poured onto 1 kg crushed ice. After 1 h, the solid was filtered and the precipitate was washed with water and dried. The dry product was washed with 100 mL ethyl acetate/petrol ether (1:9) to yield 27 g (83%) of a brownish solid: 1H-NMR (300 MHz, CDCl3): δ=8.78 (1H, s), 8.21 (1H, s) 7.98 (1H, d), 7.83 (1H, d), ppm. UPLC-MS: RT=1.28 min; m/z (ES+) 243.5 [MH+]; required MW=242.5. Mp. 145° C.

Provenance & Evidence