反应详情

To a suspension of 4,6-dichloroindolin-2,3-dione (5.95 g) in acetic acid (95 ml) was added chromium trioxide (16 g) over a period of 15 minutes at 60° C. with stirring and the mixture was stirred at 70°-75° C. for 1 hour. After cooling, the reaction mixture was poured into water (360 ml) and the resulting precipitates were collected by filtration. The filtrate was extracted with ethyl acetate. The extract was washed with water and dried. Removal of the solvent gave a residue, which was combined with the precipitates. Recrystallization from isopropyl ether gave 5,7-dichloro-2H-3,1-benzoxazine-2,4(1H)-dione (2.85 g).

1. stirringthe mixture was stirred at 70°-75° C. for 1 hour
2. temperatureAfter cooling
3. customthe resulting precipitates
4. filtrationwere collected by filtration
5. extractionThe filtrate was extracted with ethyl acetate
6. washThe extract was washed with water
7. customdried
8. customRemoval of the solvent
9. customgave a residue, which
10. customRecrystallization from isopropyl ether