Abstract The total synthesis of cyclotheonamide C (3), a macrocyclic pentapeptide incorporating an α-keto homoarginine (k-Arg) and a vinylogous dehydrotyrosine (V-ΔTyr) unit, has been achieved. For comparison of macrocyclisation feasibility, two linear pentapeptides bearing free ketone functions at the k-Arg units were prepared, by use of tandem oxidation/coupling reactions on α-keto cyanophosphorane precursors as the key ...
