[CH2:1]([O:3][C:4]([CH:6]([CH2:12][CH:13]([CH3:15])[CH3:14])[C:7]([O:9]CC)=[O:8])=[O:5])[CH3:2].[OH-].[Na+]>C(O)C>[CH2:1]([O:3][C:4]([CH:6]([CH2:12][CH:13]([CH3:14])[CH3:15])[C:7]([OH:9])=[O:8])=[O:5])[CH3:2]Ethyl 2-(ethoxycarbonyl)-4-(methyl)pentanoate (6 g., 28 mM) was dissolved in ethanol (9 ml.) and 4 N-aqueous sodium hydroxide (7 ml.) was added. The mixture was stirred at ambient temperature for 1 hour and then evaporated. The residue was diluted with water (30 ml.) and the aqueous solution was washed with diethyl ether (3×10 ml.). The combined ethereal washings were backextracted with water (5 ml.). The combined aqueous phases were acidified to pH 3 at 0° C. with citric acid, and the resulting oil was extracted into ethyl acetate (4×20 ml.). The combined extracts were washed with water (2×20 ml.) and dried (MgSO4). The mixture was filtered and the solvent was evaporated to give 2-ethoxycarbonyl-4-methylpentanoic acid as an oil. The structure was confirmed by NMR.
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