Chiral Recognition of N-Phthaloyl, N-Tetrachlorophthaloyl, and N-Naphthaloyl alpha-Amino Acids and Their Esters on Polysaccharide-Derived Chiral Stationary Phases

Abstract

Enantiomeric separations of N-phthaloyl (N-PHT), N-tetrachlorophthaloyl (N-TCPHT), and N-naphthaloyl (N-NPHT) alpha-amino acids and their esters were examined on several kinds of polysaccharide-derived chiral stationary phases (CSPs). Resolution capability of CSPs was greater Chiralcel OF than the others for N-PHT and N-NPHT alpha-amino acids and their esters. In N-TCPHT alpha-amino acids and their esters, good enantioselectivities showed Chiralcel OG for N-TCPHT alpha-amino acids, Chiralpak AD for N-TCPHT alpha-amino acid methyl esters, and Chiralcel OD for N-TCPHT alpha-amino acid ethyl esters, respectively. From the results of liquid chromatography and computational chemistry, it is concluded that l-form is preferred and more retained with electrostatic interaction in case of interaction between N-PHT alpha-amino acid derivatives and Chiralcel OF, N-TCPHT alpha-amino acid derivatives and Chiralcel OD, and N-NPHT alpha-amino acid derivatives and Chiracel OF. On the other hand, d-form is preferred and more retained with van der Waals interaction in case of interaction between N-TCPHT alpha-amino acid ester derivatives and Chiralcel OG and Chiralpak AD. Chirality 24:10371046, 2012. (c) 2012 Wiley Periodicals, Inc.