Araiosamines A−D: Tris-bromoindole Cyclic Guanidine Alkaloids from the Marine Sponge Clathria (Thalysias) araiosa
journal contributionposted on 15.07.2011, 00:00 by Xiaomei Wei, Niel M. Henriksen, Jack J. Skalicky, Mary Kay Harper, Thomas E. Cheatham, Chris M. Ireland, Ryan M. Van Wagoner
Four new tris-bromoindole cyclic guanidine alkaloids, araiosamines A−D, were isolated from the methanol extract of a marine sponge, Clathria (Thalysias) araiosa, collected from Vanuatu. Their carbon skeletons delineate a new class of indole alkaloids apparently derived from a linear polymerization process involving a carbon−carbon bond formation. Comparison of the structures including the relative configurations suggests a common intermediate containing a dihydroaminopyrimidine moiety capable of undergoing various modalities of conjugate addition to yield unprecedented ring systems.