Enantioseparation of Amino Acids on a Chiral Stationary Phase Derived from L-α-Norleucinyl- and Pyrrolidinyl-disubstituted Cyanuric Chloride by High-Performance Liquid Chromatography

Abstract

A silica-based chiral stationary phase (CSP) derived from L-α-norleucinyl- and pyrrolidinyl-disubstituted cyanuric chloride was prepared for the enantioseparation of methyl esters of N-(3,5-dinitrobenzoyl) amino acids by high-performance liquid chromatography. The chromatographic results show that effective enantioseparation of methyl esters of N-(3,5-dinitrobenzoyl)amino acids, except for proline, was achieved on this chiral stationary phase. The chromatographic resolution of racemic n-propyl ester of N-(3,5-dinitrobenzoyl)valine on CSP-B is better than that of racemic methyl ester of N-(3,5-dinitrobenzoyl)valine on CSP-B or CSP-A reported previously (J. Chromatogr. A, 676 (1994) 303). The comparison of the chromatographic results obtained in this study with those on CSP-A reported previously reveals that steric effect, instead of hydrophobic interaction, between the n-butyl group attached to the chiral center of the chiral selector and the alkyl group attached to the chiral center of the chiral selectand plays a significant role in chiral discrimination. The increase in the selectivity factor of methyl esters of N-(3,5-dinitrobenzoyl)amino acids with bulky alkyl groups was examined on CSP-B.