Enantioselective Recognition by a New Chiral Stationary Phase at the Receptor Level

A new chiral stationary phase (CSP 1) for HPLC applications has been prepd. by covalent attachment of a synthetic C3-sym., O-allyl protected tyrosyl macrocycle to γ-mercaptopropyl silica gel. CSP 1 shows exceptionally high levels of enantioselectivity for Boc-protected amino acid derivs., with sepn. factors in the 9-43 range using org. eluents; multiple H-bond interactions between the cup-shaped, immobilized C3-macrocycle and enantiomeric guests are involved in the recognition process. The preferential retention of L-Boc-protected amino acids is reversed for π-acidic 3,5-dinitrobenzoylated amino acid derivs., suggesting addnl. binding modes based on π-stacking interactions. Chromatog. data collected under reversed-phase conditions show that the macrocyclic receptor is capable of enantioselective recognition also in aq. media. In addn. to enantiomeric and diastereomeric resolns. of simple peptidic substrates, CSP 1 can resolve a large variety of racemic compds. having different types and combinations of functionalities.