Trifluoroacetic anhydride → methyl 6-chloronicotinate N-oxide

2-chloro-5-methoxycarbonylpyridine (7.0 g) and urea-hydrogen peroxide adduct (6.93 g) were suspended in acetonitrile (100 mL), and trifluoroacetic anhydride (9.92 mL) was dropwise added thereto at 0° C. The reaction mixture was stirred at room temperature for 5 hours, and evaporated in vacuo to remove the solvent. After addition of saturated aqueous sodium hydrogen carbonate and aqueous sodium thiosulfate to the residue, the mixture was extracted 5 times with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate, and filtered to remove the sodium sulfate. The organic solvent was evaporated in vacuo and the resulting residue was purified by column chromatography on silica gel (hexane:ethyl acetate=2:8) to give the title compound as a pale brown solid (8.0 g).

1. customat 0° C
2. customevaporated in vacuo
3. customto remove the solvent
4. additionAfter addition of saturated aqueous sodium hydrogen carbonate and aqueous sodium thiosulfate to the residue
5. extractionthe mixture was extracted 5 times with ethyl acetate
6. dry with materialThe organic layer was dried over anhydrous sodium sulfate
7. filtrationfiltered
8. customto remove the sodium sulfate
9. customThe organic solvent was evaporated in vacuo
10. customthe resulting residue was purified by column chromatography on silica gel (hexane:ethyl acetate=2:8)

ORD record

ord-48057088731d4289b8636eb89a59796c

Source dataset

uspto-grants-2006_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07138525B2