Unusual examples of the liquid chromatographic resolution of racemates resolution of π-donor analytes on a π-donor chiral stationary phase

A π-basic chiral stationary phase (CSP) derived from (S)-1-(6,7-dimethyl-1-naphthyl)isobutylamine was used for the resolution of the enantiomers of π-basic 3,5-dimethylanilide derivatives of non-steroidal anti-inflammatory drugs related to α-arylpropionic acids. The separation factors are large enough for analytical purposes, baseline resolution being obtained. From the resolution of 3,5-dimethylanilide, N-methyl-3,5-dimethylanilide, N-alkylamide and N,N-dialkylamide derivatives of naproxen, it was concluded that the π-basic aryl derivatizing group plays a role as a hydrogen bond acceptor in the chiral recognition process and the amide NH hydrogen of analytes is essential for chiral recognition.