PALMOSALIDE-A, PALMOSALIDE-B, AND PALMOSALIDE-C, NEW SESQUITERPENOIDS FROM THE INDIAN-OCEAN TELESTACEAN OCTOCORAL COELOGORGIA-PALMOSA

Three new sesquiterpenoid lactones, palmosalides A-C (1-3), possessing both eremophilane and bakkane carbon skeletons, have been isolated from the Indian Ocean telestacean octocoral Coelogorgia palmosa Milne Edwards & Haime. The structure determinations of the new eremophilanes, palmosalides A and B, were accomplished by NMR methods, while the structure of palmosalide C was assigned by X-ray analysis. Palmosalide C (3) belongs to the rare bakkane class of sesquiterpenoids, but it is epimeric to the known terrestrial bakkenolides at the C-7 spiro center. This is only the second telestacean to be investigated chemically, and the first report of sesquiterpenoid synthesis in this rare class of marine invertebrates. © 1990.