Earticle

An HPLC chiral stationary phase (CSP) which has only two ureide functional groups was prepared starting from (1S,2S)-1,2-diaminocyclohexane. The CSP was successful in the resolution of various N-(3,5- dinitrobenzoyl)-α-amino acids, the separation (α) and the resolution factors (RS) being within the range of 1.11-1.35 and 2.19-5.17, respectively with the use of 20% 2-propanol in hexane containing 0.1% trifluoroacetic acid as a mobile phase. However, ethyl esters of N-(3,5-dinitrobenzoyl)-α-amino acids were not resolved or resolved with only marginal separation and resolution factors on the CSP under the identical mobile phase condition. From these results, the complexation of the carboxylate anions of analytes inside the double-ureide pocket of the CSP was expected to play some important role for the chiral recognition. In contrast, N-(3,5- dinitrobenzoyl)-α-amino acid N-propylamides were resolved on the CSP with reasonable separation and resolution factors. Enantioselective hydrogen bonding interactions between analytes and the CSP were presumed to be responsible for these resolutions.