Enantiomeric separation of chiral carboxylic acids, as their diastereomeric carboxamides, by thin-layer chromatography.

A thin-layer chromatographic (TLC) method is described for the enantiomeric separation of chiral carboxylic acids using chiral derivatization and non-chiral TLC conditions (ordinary plates and mobile phases) to separate the diastereomeric carboxamides obtained. New chiral derivatizing agents, "levobase" (1R, 2R)-(-)-1-(4-nitrophenyl)-2-amino- 1,3-propanediol, and "dextrobase" (the enantiomer of levobase) are used for carboxamide formation in the presence of dicyclohexylcabodiimide as coupling agent. The procedure is very simple and convenient to carry out. Good resolution is obtained for a wide range of carboxylic acid enantiomeric pairs containing one to two chiral centres.