Phosphopeptidomimetic substance libraries from multicomponent reaction: Enantioseparation on quinidine carbamate stationary phase

In the present contribution we report a HPLC enantioseparation method for a library of amido-aminophosphonate structures generated by a novel Ugi-multicomponent reaction. The enantioseparation of these novel potentially bioactive molecules was achieved by means of HPLC on cinchona-carbamate based chiral anion-exchangers under polar organic elution conditions. The compounds were synthesized with the aim of offering a wide degree of heterogeneity in terms of structural elements to evaluate the influence of various structural motifs on enantioselectivity. The resultant compound library allows to derive structure-enantioselectivity relationships useful for understanding the chiral recognition process. As part of the study mobile phase characteristics such as concentration and type of counterion, mobile phase composition, apparent pH and temperature were investigated with regards to their effect on the separation performances. Employing a single mass spectrometry-compatible mobile phase, 23 compounds out of a pool of 42 racemic amido-aminophosphonate structures reached full baseline separation (Rs > 1.5) and 5 were almost baseline separated (1 < Rs < 1.5). This result clearly demonstrates the wide applicability of carbamoylated-cinchona alkaloids as chiral stationary phases for this class of analytes.