反应详情

温度

50 °C

Trifluoroacetic anhydride (147 mL) was added dropwise to a solution of ethyl 5-chloropyridine-2-carboxylate 1-oxide (36.8 g) in N,N-dimethylformamide (220 mL) under ice-cooling over 20 minutes, and the mixture was stirred at 50° C. for one hour. The reaction solution was ice-cooled and water was added. Sodium bicarbonate was slowly added to effect neutralization, followed by extraction with chloroform. The organic layer was dried over anhydrous magnesium sulfate and filtered. The solvent was then evaporated under reduced pressure. The residue was suspended with ethyl acetate, stirred and then filtered. The filtrate was concentrated under reduced pressure. The same operation was further repeated twice. The resulting solids were combined and dried under reduced pressure to give ethyl 5-chloro-6-hydroxypyridine-2-carboxylate as a white solid (24.2 g, 75%). The filtrate was purified by silica gel column chromatography (hexane:ethyl acetate=1:1) to give ethyl 5-chloro-6-hydroxypyridine-2-carboxylate as a white solid (1.84 g, 6%).

1. temperaturecooling over 20 minutes
2. temperaturecooled
3. extractionfollowed by extraction with chloroform
4. dry with materialThe organic layer was dried over anhydrous magnesium sulfate
5. filtrationfiltered
6. customThe solvent was then evaporated under reduced pressure
7. stirringstirred
8. filtrationfiltered
9. concentrationThe filtrate was concentrated under reduced pressure
10. customdried under reduced pressure