Water → 1-(3,4-dihydro-2H-1-benzopyran-6-yl)-4,4,4-trifluorobutane-1,3-dione

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Reaction Steps

Under a nitrogen atmosphere, 1-(3,4-dihydro-2H-1-benzopyran-6-yl)ethan-1-one (49a) (1.55 g, 8.8 mmol) was dissolved in anhydrous tetrahydrofuran (48 mL) and sodium hydride (60% in mineral oil, 0.42 g, 10.6 mmol) was added portionwise, maintaining the temperature between −5 and 0° C. After 30 minutes stirring at the same temperature, ethyl trifluoroacetate (1.5 mL, 10.6 mmol) was added and the reaction mixture was stirred at room temperature for 3 hours. Water (10 mL) was added and tetrahydrofuran was removed in vacuo. The resulting aqueous layer was extracted with ethyl acetate (2×20 mL). The organic layer was washed with brine (10 mL), dried over sodium sulfate and concentrated in vacuo to provide 1-(3,4-dihydro-2H-1-benzopyran-6-yl)-4,4,4-trifluorobutane-1,3-dione (49b) (2.39 g, 8.8 mmol, 100%) which was used without further purification.

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