TOTAL SYNTHESIS OF NONNATURAL COMPOUNDS FOR MOLECULAR RECOGNITION - THE DOUBLE CHALLENGE

Molecular recognition of biomolecules by synthetic receptors requires modular assembly of various components to complement the molecular cha racteristics (sizes, topologies, and functional groups) of the substra te. A number of receptors for biorelevant molecules containing oxoanio ns have been assembled from a bicyclic chiral guanidine subunit. Sever al receptors accelerate or catalyze reactions proceeding through anion ic transition states. Among the structures recently prepared, a recept or incorporating a calix[6]arene subunit has been developed, showing h igh affinity for phosphocholine derivatives. Chains of tetraguanidiniu m sulfates form double helices in solution. These substances strongly induce formation of alpha-helical conformations in Asp rich peptides.