New cembranolides from the gorgonian Eunicea succinea

A new chemical study of the Caribbean gorgonian Eunicea succinea collected in Puerto Rico afforded seven new cembranolides (1-5, 7, and 8). Excepting 1, the new compounds described here possess an unusual unsaturation at either position C-1, C-6, or C-8, and all but 8 possess the C-12R, C-13S stereochemistry usually ascribed to cembranolides from E. succinea. Their chemical structures were carefully established by a combination of chemical and spectroscopic methods in addition to detailed NMR spectral comparisons with known cembranolide models.