C([O:3][C:4](=[O:17])[CH:5]([CH2:11][CH:12]([CH2:15][CH3:16])[CH2:13][CH3:14])[C:6]([O:8]CC)=[O:7])C.[OH-].[K+]>C(O)C.O>[CH2:15]([CH:12]([CH2:13][CH3:14])[CH2:11][CH:5]([C:6]([OH:8])=[O:7])[C:4]([OH:17])=[O:3])[CH3:16]A solution of 2-(2-ethyl-butyl)-malonic acid diethyl ester (4.78 g, 19.5 mmol) in ethanol (43.5 mL) was treated with a solution of potassium hydroxide (3.3 g, 58.7 mmol) in water (10.9 mL). The reaction was then heated to 105° C. for 6 h. After this time, the reaction was concentrated in vacuo. The residue was diluted with water (50 mL) which was then acidified with a 2N aqueous hydrochloric acid solution and then extracted with a 90/10 methylene chloride/methanol solution (3×50 mL). The combined organics were dried over sodium sulfate, filtered and concentrated in vacuo to afford 2-(2-ethyl-butyl)-malonic acid (3.55 g, 96%) as an off-white solid, which was used without further purification; EI+-HRMS m/e calcd for C9H16O4 [M+Na]+ 211.0941, found 211.0941. 1H NMR (300 MHz, DMSO-d6) δ ppm 0.79 (t, J=7.4 Hz, 6H) 1.09-1.39 (m, 5H) 1.65 (t, J=7.1 Hz, 2H) 3.22 (t, J=7.5 Hz, 1H) 12.65 (br. s., 2H).
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