Hydrochloric Acid → 2,3,4-Trifluoro-5-pivaloylaminophenol

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Reaction Steps

1.27 g (5.40 mmol) of the above 5-amino-O-ethoxycarbonyl-2,3,4-trifluorophenol was dissolved in 5 mL of pyridine, 0.80 mL (6.5 mmol) of pivaloyl chloride was added under ice-cooling and the mixture was stirred at the same temperature for 15 minutes. 1N hydrochloric acid was added to the reaction solution and the mixture was extracted once with ethyl acetate. The organic layer was washed once with water and once with an aqueous saturated solution of sodium chloride, dried over anhydrous sodium sulfate and the solvent was distilled off under reduced pressure. The residue was dissolved in 25 mL of methanol, 1.40 g (10.1 mmol) of potassium carbonate and 15 mL of water were added and the mixture was stirred at room temperature for 4 hours. The reaction solution was adjusted to pH 2 by addition of 2N hydrochloric acid thereto and the mixture was extracted once with ethyl acetate. The organic layer was washed once with water and once with an aqueous saturated solution of sodium chloride, and dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure to give 1.20 g of 2,3,4-trifluoro-5-pivaloylaminophenol (two stage yield: 90%).

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