Benzosceptrins A and B with a Unique Benzocyclobutane Skeleton and Nagelamide S and T from Pacific Sponges

Abstract

Four new dimeric pyrrole-2-aminoimidazole alkaloids have been isolated from the Pacific marine sponges <i>Agelas cf. mauritiana</i> and <i>Phakellia</i> sp. They include the unusual C2 symmetrical benzosceptrins A (<b>4</b>) and B (<b>5</b>), which each possess a unique benzocyclobutane skeleton and nagelamides S (<b>6</b>) and T (<b>7</b>). Their structures and relative configuration were elucidated from spectroscopic data. Plausible biogenetic paths for these compounds are also proposed in this paper.