2,2-Dimethyl-1,3-dioxane-4,6-dione → 2,2-Dimethyl-5-[2-(2,4,5-trifluoro-phenyl)-acetyl]-[1,3]dioxane-4,6-dione

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Reaction Steps

2,2-Dimethyl-[1,3]dioxane-4,6-dione (5.69 g, 39.5 mmol) was dissolved in 400 mL of dichloromethane under stirring, followed by addition of 2,4,5-trifluorophenyl acetic acid 1a (7.15 g, 37.6 mmol) and 4-dimethylaminopyridine (7.35 g, 60.2 mmol) in an ice-water bath. Then a suspension of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (8.28 g, 43.2 mmol) in 250 mL of dichloromethane was added dropwise slowly. After stirring at room temperature for 36 hours, the reaction mixture was washed with the solution of 5% potassium bisulfate (250 mL×7) and saturated brine (250 mL×2), dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to obtain the title compound 2,2-dimethyl-5-[2-(2,4,5-trifluorophenyl)-acetyl]-[1,3]dioxane-4,6-dione 1b (11.4 g, yield 96%) as a white solid. MS m/z (ESI): 315.5 [M−1].

Provenance & Evidence