Total Synthesis of Cyclotheonamide C using a Tandem Backbone‐Extension–Coupling Methodology

Mastering unusual amino acids : The first total synthesis of the potent protease inhibitor cyclotheonamide C (see structure representation) has been achieved. The key features of the synthesis are a three‐component tandem procedure to create a masked α‐keto‐β‐arginine within a peptide chain, and the control of the extended conjugation of a vinylogous α,β‐dehydrotyrosine.