Direct liquid chromatographic enantioseparation of chiral α- and β-aminophosphonic acids employing quinine-derived chiral anion exchangers: determination of enantiomeric excess and verification of absolute configuration Original Research Article

Four types of quinine-derived chiral anion exchangers were used for the direct liquid chromatographic separation of enantiomers of chiral but N-protected α- and β-aminophosphonic acids. The respective and easily prepared 3,5-dinitrobenzyloxycarbonyl and dinitrophenyl derivatives were well separated, yielding α-values between 1.1 and 2.8 and resolution values in the range 2.0–9.0. Besides the chromatographic investigations, data on enantiomeric excesses (ees) and the absolute configurations of some enantiomerically enriched α- and β-aminophosphonic acids prepared by stereoselective synthesis were also determined. The results obtained by this method (ee and absolute configuration) correspond well with the results previously obtained by a 31P-NMR spectroscopic method.