Water → 7-trifluoromethyl-1H-pyrido[2,3-b][1,4]oxazin-2-one

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Reaction Steps

In a 10 ml flask, (3-nitro-5-trifluoromethyl-pyridin-2-yloxy)-acetic acid methyl ester (84 mg, 0.30 mmol) was dissolved in concentrated hydrochloric acid (1.5 ml) and then tin tetrachloride (227 mg, 1.2 mmol) was added thereto. The mixture was stirred for 30 minutes at 80□. After completion of the reaction, water was added thereto at room temperature and the mixture was extracted with a solvent of methanol: dichloromethane=1:9. The combined organic layer was dried over anhydrous sodium sulfate (Na2SO4), filtered and evaporated under reduced pressure. The residue was purified by column chromatography on silica eluting with a solvent of methanol:dichloromethane=1:50. The fractions containing the product were collected and evaporated to obtain white solid (40 mg, 62%).

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