SEPARATION OF THE ENANTIOMERS OF THE 3,5-DINITROBENZAMIDE DERIVATIVES OF ALPHA-AMINO PHOSPHONATES ON 4 CHIRAL STATIONARY PHASES

Four commercially available high-performance liquid chromatography columns containing chiral stationary phases (CSPs) have been evaluated for the separation of the enantiomers of a variety of alpha-amino phosphonates as the 3,5-dinitrobenzamide derivatives. The CSPs are divided into two mechanistic classes, the pi-acidic N-(3,5-dinitrobenzoyl)phenylglycine/N-(3,5-dinitrobenzoyl)leucine class and the pi-basic N-(2-naphthyl)alanine/N-(1-naphthyl)leucine class. As expected, the pi-basic CSPs are found to be more effective for separating the enantiomers of these pi-acidic analytes, separation factors being sufficiently large to make preparative or reversed-phase separations possible. A chiral recognition rationale consistent with the observed elution orders is postulated for the pi-basic CSPs.