Liquid chromatographic resolution of 2-hydroxycarboxylic acids a new chiral stationary phase derived from (S)-leucine

Enantiomers of racemic 2-hydroxycarboxylic acids have been resolved as thei r O-ethoxycarbonyl pi-basic anilide derivatives on a new chiral stationary phase (CSP) derived from N-(3,5-dinitrobenzoyl)leucine N-phenyl N-alkylamid e and the resolution results have been compared with those on various comme rcial pi-acidic CSPs. The resolution results demonstrate that the new CSP d erived from N-(3,5-dinitrobenzoyl)leucine N-phenyl N-alkylamide is most eff ective among the five CSPs tested for the resolution of 2-hydroxycarboxylic acid derivatives. In order to elucidate the chiral recognition mechanism e xerted by the new CSP, the resolution of slightly differently modified deri vatives of 2-hydroxycarboxylic acids on me new CSP has been investigated. B ased on the resolution results, a chiral recognition mechanism utilizing th ree simultaneous interactions such as the face to face pi-pi interaction an d the two hydrogen bonding interactions between the CSP and the more retain ed enantiomer of the analyte has been proposed. (C) 2000 Elsevier Science B N. All rights reserved.