反应详情

To a solution of 2-(2,6-difluorophenyl)-3-fluoro-6-methylpyridine (1.0 equiv.) in water (0.05 M) was added KMnO4 (2.0 equiv.) and the reaction was heated to reflux overnight. Another 2.0 equiv. of KMnO4 were added and stirred at reflux for another 8 hours. The solution was cooled to room temperature, filtered through Celite and washed with water. The filtrate was acidified with 6N HCl to pH=3, the white precipitate was filtered. The filtrate was further acidified to pH=1 and filtered again. The filtrate was extracted with ethyl acetate until no more product in the aqueous layer. The organic phase was washed with brine and dried over magnesium sulfate, filtered, and concentrated. The residue was dissolved in ethyl acetate, washed with 1N NaOH, the aqueous layer was acidified to pH=1 and the white crystals were filtered. The combined products yielded 6-(2,6-difluorophenyl)-5-fluoropicolinic acid in 32% yield as a white solid. LC/MS=254.0 (M+H), Rt=0.71 min.

1. temperaturethe reaction was heated
2. temperatureto reflux overnight
3. temperatureat reflux for another 8 hours
4. filtrationfiltered through Celite
5. washwashed with water
6. filtrationthe white precipitate was filtered
7. filtrationfiltered again
8. extractionThe filtrate was extracted with ethyl acetate until no more product in the aqueous layer
9. washThe organic phase was washed with brine
10. dry with materialdried over magnesium sulfate
11. filtrationfiltered
12. concentrationconcentrated
13. dissolutionThe residue was dissolved in ethyl acetate
14. washwashed with 1N NaOH
15. filtrationthe white crystals were filtered