反应详情

A solution of 7,8-dimethoxy-quinoxalin-2-one (5.0 g, 24.25 mmol, 1.0 eq) in phosphorus oxychloride (25 mL, 268.21 mmol, 11.06 eq) is heated under reflux for 1 hour. Then the reaction mixture is cooled down to room temperature and the solvent is evaporated. The residue is poured into ice water, the resulting mixture is neutralized with saturated sodium hydrogen carbonate and extracted with ethyl acetate (3×50 mL). The combined organic layers are dried over sodium sulfate, filtered and concentrated to give a crude product that is purified by column chromatography (silica gel, eluent: hexane:ethyl acetate, 2:1 to 1:1, v/v) to afford 2-chloro-7,8-dimethoxy-quinoxaline as a light yellow solid (4.2 g, 77% yield).

1. temperatureunder reflux for 1 hour
2. customthe solvent is evaporated
3. additionThe residue is poured into ice water
4. extractionextracted with ethyl acetate (3×50 mL)
5. dry with materialThe combined organic layers are dried over sodium sulfate
6. filtrationfiltered
7. concentrationconcentrated
8. customto give a crude product that
9. customis purified by column chromatography (silica gel, eluent