Intricarene, an unprecedented trispiropentacyclic diterpene from the Caribbean sea plume Pseudopterogorgia kallos

A novel trispiropentacyclic diterpene, intricarene (1), was isolated from the hexane extract of the Caribbean gorgonian octocoral Pseudopterogorgia kallos. Its highly entangled structure was established by interpretation of NMR, IR, UV, and HREIMS data and subsequently confirmed by X-ray diffraction analysis. The unprecedented carbon skeleton of I constitutes a new addition to the already impressive architectural diversity of the diterpene class of marine secondary metabolites.