| 摘要 |
PROBLEM TO BE SOLVED: To provide a racemic carboxylic acid suitable for producing an optically active carboxylic acid useful for a medicine, etc., by a simple operation with small amounts of reagents from an optical isomer recovered by an optical resolution method by mixing a specific optically active carboxylic acid with a prescribed acid anhydride and heating the mixture in the presence of a base. SOLUTION: (A) An optically active carboxylic acid containing a carboxyl group bonded to an asymmetric carbon atom [e.g. (R)-tetrahydrofuran-2- carboxylic acid or the like] is reacted with (B) an acid anhydride of the formula (R1-CO)2O (R1 is a 1-12C alkyl which is not substituted or substituted with a 1-12C alkyl or the like) (e.g. acetic anhydride or the like) in the ratio of preferably 0.01-0.4 equivalent of the component B based on the component A and heated in the presence of (C) a base being a tertiary amine such as preferably triethylamine or the like favorably at 50-150 deg.C generally for 1-20 hours to give the objective compound (e.g. tetrahydrofuran-2-carboxylic acid or the like).
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