Ethyl Acetate → 1-Cyclopropyl-butane-1,3-dione

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To a stirring solution of THF (100 mL) was added potassium tert-butoxide (5.60 g, 49.5 mmol), followed by a mixture of cyclopropyl methyl ketone (3.27 mL, 33 mmol) and ethyl acetate (9.69 mL, 99 mmol) in 30 mL THF at 35° C., via addition funnel over a 25 min period. The contents were heated and stirred at 60° C. After 3 h, the contents were removed from heating, and allowed to cool to room temperature. The reaction mixture was carefully diluted with 30 mL 2 N HCl and stirred for 10 min. The mixture was extracted with diethyl ether (3×50 mL), and the combined organic layers washed with brine (1×50 mL). The organic layer was dried over MgSO4, filtered, and concentrated in vacuo. Purification by chromatography on silica gel (eluent: 0 to 15% EtOAc in hexanes) with good separation afforded 1-cyclopropyl-1,3-butanedione as a light yellow colored oil, 3.9 g in ˜75% purity (residual solvent), for an overall yield of 70%. 1H NMR (400 MHz, CDCl3) δ ppm 0.89-0.96 (m, 2H), 1.09-1.15 (m, 2H), 1.59-1.69 (m, 1H), 2.04 (s, 3H), 5.63 (s, 1H), 15.5-16.0 (br s, 1H).

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