反应详情

温度

140 °C

To a flaske charged with polyphosphoric acid (396 g, 4038 mmol) was added 5-bromo-4-fluoro-2-(2-fluoro-4-methoxyphenoxy)benzoic acid (58 g, 162 mmol) and the viscous mixture was heated at 140° C. for 2 hours. The viscous solution was cooled slightly and diluted with ice-water (1 L). After 15 min of stirring, EtOAc (1 L) was added and the aqueous fraction extracted with EtOAc (3×200 mL). The combined organic fractions were dried over sodium sulfate and concentrated. The solids were washed with 6 N NaOH, then water. The solids were then sequentially triturated with methanol and ethyl acetate. The resulting solid was dried under vacuum to afford 2-bromo-3,5-difluoro-7-methoxy-9H-xanthen-9-one (41 g, 120 mmol, 74.4% yield).

1. temperatureThe viscous solution was cooled slightly
2. extractionthe aqueous fraction extracted with EtOAc (3×200 mL)
3. dry with materialThe combined organic fractions were dried over sodium sulfate
4. concentrationconcentrated
5. washThe solids were washed with 6 N NaOH
6. customThe solids were then sequentially triturated with methanol and ethyl acetate
7. customThe resulting solid was dried under vacuum