Ethanol → Trans-4-(2-oxo-pyrrolidin-1-yl)cyclohexanecarboxylic acid

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Reaction Steps

To ethyl 4-(2-pyrrolidon-1-yl)cyclohexylcarboxylate (5.0 g, mixture of cis and trans isomers, cis:trans=61:39) are added ethanol (25.0 mL, 5V/W) and sodium ethoxide (2.0 equiv. 0.0132 mol), and the mixture is stirred at room temperature for 20 hours. After adding water (5.0 mL, 1V/W), the reaction solution is stirred at room temperature for 2 hours, and evaporated to remove ethanol under reduced pressure. The residue is acidified by adding 2 N hydrochloric acid, and thereto is added an excessive amount of crystalline sodium chloride followed by extraction with methylene chloride. The extract is dried, and evaporated to remove the solvent under reduced pressure. The resulting crystals are collected with toluene to give 4-(2-pyrrolidon-1-yl)cyclohexylcarboxylic acid (2.9 g, trans:cis=88:12, yield 58%).

Provenance & Evidence