ENANTIOSELECTIVE HOSTS FOR NEUTRAL DERIVATIVES OF AMINO-ACIDS

A series of macropolycyclic receptors for hydrogen bond donor/acceptor guests were prepared and studied. Molecular modeling and X-ray crystallography provided structural information, while NMR titration studies allowed determination of free energies of association. Some of the receptors prepared showed enantioselectivity as high as 3 kcal/mol in binding derivatives of simple amino acids in organic solvents. These studies show that conformational homogeneity is one of the most important characteristics of a selective host and that molecular modeling can play an important role in the design of such substances.