Solid-Supported Synthesis of a Peptide β-Turn Mimetic

The solid-supported synthesis of a bicyclic diketopiperazine, a potential peptide β-turn mimetic, is described. The Ugi reaction between the resin ester of α-<i>N</i>-Boc-diaminopropionic acid (an amine input), α-bromo acid, aldehyde, and isocyanide is the key step in the proposed protocol.