Direct liquid chromatographic enantioseparation of chiral alpha- and beta-aminophosphonic acids employing quinine-derived chiral anion exchangers: determination of enantiomeric excess and verification of absolute configuration

Four types of quinine-derived chiral anion exchangers were used for the dir ect liquid chromatographic separation of enantiomers of chiral but N-protec ted alpha- and beta-aminophosphonic acids. The respective and easily prepar ed 3,5-dinitrobenzyloxycarbonyl and dinitrophenyl derivatives were well sep arated, yielding alpha-values between 1.1 and 2.8 and resolution values in the range 2.0-9.0. Besides the chromatographic investigations, data on enan tiomeric excesses tees) and the absolute configurations of some enantiomeri cally enriched alpha- and beta-aminophosphonic acids prepared by stereosele ctive synthesis were also determined. The results obtained by this method t ee and absolute configuration) correspond well with the results previously obtained by a P-31-NMR spectroscopic method. (C)2000 Elsevier Science B.V. All rights reserved.