In the enantiomeric separation of highly polar compounds, a traditionally challenging task for high-performance liquid chromatography, ion-exchange chiral stationary phases have found the main field of application. In this contribution, we present a series of novel anion-exchange-type chiral stationary phases for enantiomer separation of protected amino phosphonates and N-protected amino acids. Two of the prepared selectors possessed a double and triple bond within a single molecule. Thus, they were immobilized onto silica support employing either a thiol-ene (radical) or an azide-yne (copper(I)-catalyzed) click reaction. We evaluated the selectivity and the effect of immobilization proceeding either by the double bond of the Cinchona alkaloid or a triple bond of the carbamoyl moiety on the chromatographic performance of the chiral stationary phases using analytes with protecting groups of different size, flexibility, and π-acidity. The previously observed preference toward protecting groups possessing π-acidic units, which is a typical feature of Cinchona-based chiral stationary phases, was preserved. In addition, increasing the bulkiness of the selectors' carbamoyl units leads to significantly reduced retention times, while very high selectivity toward the tested analytes is retained.

Department of Analytical Chemistry University of Vienna Vienna Austria

Department of Internal Medicine Nephrology University of Michigan Ann Arbor MI USA

Department of Organic Chemistry University of Chemistry and Technology Prague Prague Czech Republic

Division of Chemistry of Renewable Resources Department of Chemistry University of Natural Resources and Life Sciences Tulln Austria

Institute of Organic Chemistry and Biochemistry The Academy of Sciences of the Czech Republic Prague Czech Republic

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