765-43-5

141-78-6

21573-10-4

1. Sodium hydride (60% dispersion in oil, 0.95 g, 23.8 mmol) was washed several times with pentane and then suspended in 18 ml of anhydrous tetrahydrofuran under nitrogen protection. 2. To the above suspension was added ethyl acetate (2.3 ml, 23.5 mmol) and 2 drops of ethanol. 3. A solution of cyclopropylmethyl ketone (1.0 g, 11.9 mmol) dissolved in 5 ml of anhydrous tetrahydrofuran was added dropwise with stirring while the reaction temperature was controlled below 20 °C using an ice bath. 4. After addition of 18-crown-6 (63 mg, 0.25 mmol), the reaction mixture was stirred at 40 °C for 4 hours. 5. After completion of the reaction, the solvent was removed by evaporation under reduced pressure and the residue was partitioned between ether and water. 6. The aqueous phase was separated and washed with ether. 7. The aqueous solution was acidified to pH 2 with 2N hydrochloric acid. 8. The acidified aqueous solution was extracted three times with ether and the organic phases were combined. 9. The organic phase was washed with brine, dried over anhydrous sodium sulfate, filtered and evaporated under reduced pressure to give cyclopropyl-1,3-butanedione (0.7 g, 5.5 mmol, 47% yield). 10. The product was analyzed to show 100% purity and the structure was confirmed by 1H NMR and UPLC/MS.