CHIRAL RECOGNITION OF N-ACYL-1-(2-FLUORENYL)-1-AMINOALKANES BY PI-ACIDIC CHIRAL STATIONARY PHASES - A MECHANISTIC VIEW

The enantiomers of N-acyl-1-(2-fluorenyl)-1-aminoalkanes are separable on a number of chiral stationary phases derived from N-(3,5-dinitrobenzoyl)amino acid esters and amides. Previously, these separations and some structure-dependent inversions in the elution order of the enantiomers of these analytes were rationalized on the basis of two competing chiral recognition mechanisms, one involving stacking of amide dipoles, the other hydrogen bonding. To rationalize data obtained using several new chiral stationary phases not available at the time of the original study, the original mechanistic proposal accounting for the origins of chiral recognition for these analytes is now modified. Two competing hydrogen bonding mechanisms, each modified by attendant intercalation effects, are thought to better account for the experimental observations.