Highly Oxygenated Pseudopterane and Cembranolide Diterpenes from the Caribbean Sea Feather Pseudopterogorgia bipinnata

A chemical study of the sea feather Pseudopterogorgia bipinnata from Colombia has produced four known metabolites, namely, kallolide A (1), bipinnatin A (2), bipinnatin C (3), and bipinnatin J (4), in addition to nine previously undescribed diterpenes possessing an uncommonly high level of oxygenation. One of them, bipinnapterolide A (5), is a new representative of the pseudopterane family of diterpenes possessing the rare 2,3-epoxy-1,4-dione moiety. The other metabolites, bipinnatins G-I (6-8) and bipinnatolides F-J (9-13), are highly oxygenated cembranolide diterpenes. Their chemical structures including relative stereochemistry were established by detailed analysis of the spectral data in addition to X-ray diffraction analysis and NMR spectral comparisons with known pseudopterane and cembranolide models.