反应详情

温度

200 °C

To a mixture of 2-amino-5-bromo-pyridine-3-carboxylic acid (1 g) and 6-amino-2,3-difluoro-phenol (0.669 g) placed in a round bottom flask was added polyphosphoric acid (10 g). The mixture was heated at 200° C. for 5 hours. A homogenous black mixture was obtained. The mixture was diluted in water and neutralizing to pH 8 with NaOH 2N. The heterogeneous mixture was diluted with dichloromethane. The insoluble was filtered. The organic phase was separated. The aqueous phase was extracted twice with dichloromethane. The combined organic phases were washed with brine, dried on sodium sulfate, evaporated and dried to afford 5-bromo-3-(6,7-difluoro-1,3-benzoxazol-2-yl)pyridin-2-amine (0.338 g). NMR Spectrum: (DMSOd6) 7.54 (ddd, 1H), 7.70 (ddd, 1H), 7.79 (bs, 2H), 8.34 (d, 1H), 8.38 (d, 1H); Mass spectrum: M+H+ 326-328

1. customplaced in a round bottom flask
2. customA homogenous black mixture was obtained
3. filtrationThe insoluble was filtered
4. customThe organic phase was separated
5. extractionThe aqueous phase was extracted twice with dichloromethane
6. washThe combined organic phases were washed with brine
7. customdried on sodium sulfate
8. customevaporated
9. customdried