A Modular Synthesis of Conformationally Preorganised Extended β-Strand Peptidomimetics

A promising strategy for mediating protein-protein interactions is the use of non-peptidic mimics of secondary structural protein elements, such as the α-helix. Recent work has expanded the scope of this approach by providing proof-of-principle scaffolds that are conformationally biased to mimic the projection of side-chains from one face of another common secondary structural element-the β-strand. Herein, we present a synthetic route that has key advantages over previous work: monomers bearing an amino acid side-chain were pre-formed before rapid assembly to peptidomimetics through a modular, iterative strategy. The resultant oligomers of alternating pyridyl and six-membered cyclic ureas accurately reproduce a recognition domain of several amino acid residues of a β-strand, demonstrated herein by mimicry of the i, i+2, i+4 and i+6 residues.