Diethyl Carbonate → 6-Fluoro-4-hydroxycoumarin

Participants

Reaction Steps

1-(5-Fluoro-2-hydroxy-phenyl)-ethanone (1.54 g, 10 mmol) and diethylcarbonate (2.42 mL, 20 mmol) were placed in a dry flask and dissolved in anhydrous tetrahydrofuran (30 mL.) The solution was then added drop-wise via cannula to a rapidly stirring solution of potassium tert-butoxide in tetrahydrofuran (1.0 M, 30 mL) The reaction was permitted to stir overnight (10 h) at room temperature under positive pressure of nitrogen. The crude reaction was concentrated under reduced pressure and partitioned between methyl tert-butyl ether and water. The layers were separated and the organic phase discarded. The aqueous phase was acidified to pH 5 and extracted three times with equal volumes of methylene chloride. The combined organic phases were dried over sodium sulfate and concentrated to give the title compound (1.4 g, 78% yield.) MS ESI(−) m/e: 179.16 (M−1).

Provenance & Evidence