Preparation of a New π-Basic Chiral Stationary Phase Based on Cefaclor and the Liquid Chromatographic Resolution of π-Acidic Analytes

Abstract

A new liquid chromatographic chiral stationary phase (CSP) was prepared by bonding N-(3,5-dimethoxybenzoyl)cefaclor to spherical silica gel. The new CSP was successfully utilized for the resolution of racemic N-(3,5-dinitrobenzoyl)-α-amino acid derivatives and racemic 3-substituted 1,4-benzodiazepin-2-ones. For the resolution of racemic N-(3,5-dinitrobenzoyl)-α-amino acid derivatives on the CSP, a chiral recognition mechanism utilizing the enantioselective π−π donor–acceptor interaction between the π-basic 3,5-dimethoxybenzoyl group of the CSP and the π-acidic 3,5-dinitrobenzoyl group of analytes was proposed.

Keywords:

• Cefaclor
• Chiral stationary phase
• Enantiomer separation
• Liquid chromatography

ACKNOWLEDGMENTS

This work was supported by a grant-in-aid for the National Core Research Center Program from MEST and KOSEF (R15-2006-022-03001-0).

Manuscript 6427

Notes

^a Mobile phase: 20% isopropyl alcohol in hexane. Flow rate: 1.0 mL/min. Detection: 254 nm UV. Temperature: 20°C. k ₁: Retention factor of the first eluted enantiomer. The absolute configuration of the first eluted enantiomer is presented in the parenthesis. k ₂: Retention factor of the second eluted enantiomer. The absolute configuration of the second eluted enantiomer is presented in the parenthesis. α: Separation factor.

^a Mobile phase: 20% ethyl alcohol in hexane. Flow rate: 1.0 mL/min. Detection: 254 nm UV. Temperature: 20°C. k ₁: Retention factor of the first eluted enantiomer. The absolute configuration of the first eluted enantiomer is presented in the parenthesis. k ₂: Retention factor of the second eluted enantiomer. The absolute configuration of the second eluted enantiomer is presented in the parenthesis. α: Separation factor.

^a Mobile phase: 20% ethyl alcohol in hexane. Flow rate: 1.0 mL/min. Detection: 254 nm UV. Temperature: 20°C. k ₁: Retention factor of the first eluted enantiomer. The absolute configuration of the first eluted enantiomer is presented in the parenthesis. k ₂: Retention factor of the second eluted enantiomer. The absolute configuration of the second eluted enantiomer is presented in the parenthesis. α: Separation factor.

^a Mobile phase: 20% isopropyl alcohol in hexane. Flow rate: 1.0 mL/min. Detection: 254 nm UV. Temperature: 20°C. k ₁: Retention factor of the first eluted enantiomer. The absolute configuration of the first eluted enantiomer is presented in the parenthesis. k ₂: Retention factor of the second eluted enantiomer. The absolute configuration of the second eluted enantiomer is presented in the parenthesis. α: Separation factor.