Total Synthesis of Cordyheptapeptide A

Abstract

The first total synthesis of cordyheptapeptide A is described. The synthesis is accomplished by a convergent approach featuring a combination of peptide coupling and the Ugi reaction for the preparation of the main building blocks and the acyclic precursor. The assembly of an N-methylated fragment by the Ugi reaction comprised the utilization of a convertible isonitrile followed by activation of the C-terminal amide. Two different macrocyclization sites were evaluated, proving greater efficacy the macrolactamization at the site Ile-Tyr, likely due of a more suitable conformational bias of the acyclic precursor having an internal β-turn centered at the N-Me-d-Phe-Pro moiety.