Total Synthesis of the Marine Sponge Alkaloid Motuporamine C Using a Ramberg‐Bäcklund Ring Contraction Strategy

Abstract

A new total synthesis of the marine alkaloid motuporamine C, a macrocyclic polyamine alkaloid from the marine sponge Xestospongia exigua, has been accomplished. Key steps of this synthesis include application of Ramberg‐Bäcklund rearrangement for achieving the 15‐membered aza‐macrocyclic alkene and Rh(II)‐catalyzed deoxygenation of epoxide for the conversion of E‐ to Z‐configuration of the double bond within the cyclic structure.