Reversed-phase chromatographic resolution of N-(3,5-dinitrobezoyl)- α-amino acids on chiral stationary phases

Abstract

The enantiomers of N-(3,5-dinitrobenzoyl)-α-amino acids are readily separated by reversed-phase chromatography on chiral stationary phases. Lipophilic interactions are quite important and largely determine the relative contributions of two competing “opposite sense” chiral recognition processes. Selectivities are fairly high and, on chiral phases 2a, derived from ( R)-N-(11-triethoxysilylundecanoyl)cyclohexyl (6,7-dimethyl-1-naphthyl)methylamine, are adequate for preparative separation as well as analytical separations. The ( S)-enantiomers consistently elute last from the ( R)-2a column. Chiral recognition models are proposed to accomodate the observed separability factors and elution orders.