Chemical Diversity in the Mediterranean Sponge Raspaciona aculeata: Structure and Absolute Stereochemistry of Blanesin

Several samples of Raspaciona aculeata collected from the same area (Blanes) displayed completely different metabolite patterns characterized either by already known triterpenes, raspacionins, or by blanesin (2). Blanesin is a new ent-labdane furanoditerpenoid with an a-hydroxyketone in the ring A. Structure and absolute stereochemistry were established by spectroscopic and chemical methods.