13-Epi-9-deacetoxyxenicin, a Cytotoxic Diterpene from the Soft Coral Asterospicularia laurae (Alcyonacea)

An investigation of the soft coral Asterospicularia laurae collected on the Great Barrier Reef, Australia, afforded the cytotoxic diterpene 13-epi-9-deacetoxyxenicin (1) in addition to the known metabolites 13-epi-9-deacetylxenicin (2) and gorgosterol. 13-Epi-9-deacetoxyxenicin readily underwent an autoxidation reaction in solution to afford a single product, the hydroperoxide 3. Structures, stereochemistry, and NMR assignments were established by high resolution NMR spectroscopy and by comparison with published data for known compounds.