Synthesis
The general procedure for the synthesis of 2-cyclopropyl-2-oxoacetic acid from cyclopropylmethyl ketone was as follows: 1-cyclopropylethanone (10 g, 8.9 mmol) and sodium carbonate (145 mg, 1.36 mmol) were dissolved in water (66 ml) and heated at 50 °C. Subsequently, an aqueous solution of potassium permanganate (KMnO4, 19.8 g, 125.2 mmol) was slowly added (594 ml) at this temperature over a period of 10 hours. After completion of the reaction, the reaction was terminated by addition of methanol (90 ml). The reaction mixture was filtered and the filtrate was concentrated to give a white solid. The solid was dissolved in acetone (80 ml) and heated at 65 °C for 30 min, then cooled to room temperature to precipitate a white solid. The precipitate was collected by filtration and dried to give the target product 2-cyclopropyl-2-oxoacetic acid (10 g, 74% yield) as a white solid. Mass spectrum (m/z) [M-1] ~ 113.0. nuclear magnetic resonance hydrogen spectrum (1H NMR, CD3OD): δ 2.49-2.43 (1H, m), 1.06-0.98 (4H, m).
References
[1] Patent: WO2012/71684, 2012, A1. Location in patent: Page/Page column 22
[2] Patent: US2013/224107, 2013, A1. Location in patent: Paragraph 0132; 0133; 0134
[3] Journal of the American Chemical Society, 2011, vol. 133, # 34, p. 13614 - 13621
[4] Organic letters, 2000, vol. 2, # 10, p. 1345 - 1348
[5] Helvetica Chimica Acta, 1969, vol. 52, p. 1146 - 1156
