Trifluoroacetic anhydride → 2,6-dichloro-4-methyl-nicotinic acid-N-oxide

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Reaction Steps

2,6-Dichloro-4-methyl-nicotinic acid (0.234 g, 1.14 mmol) and hydrogen peroxide-urea adduct (0.537 g, 5.70 mmol) were suspended in CH2Cl2 to give a white slurry. Trifluoroacetic anhydride (0.65 ml, 4.67 mmol) was added dropwise over 5 minutes and the resulting pale yellow solution was stirred overnight at rt. The reaction mixture was quenched with water (10 ml) and then dry loaded onto silica gel and purified using column chromatography (MeCN/MeOH/NH4OH, 8:1:1, v/v/v) to give 2,6-dichloro-4-methyl-nicotinic acid-N-oxide as a pale yellow crystalline solid (0.103 g, 41%). 1H NMR (CD3OD) δ 2.37 (s, 3H), 7.60 (s, 1H).

Provenance & Evidence