Further studies of the terpenoid content in the gorgonian Eunicea succinea: 12,13-bisepieupalmerin, a new cembranolide.

In a continuing comparative study of the sesquiterpenoid and diterpenoid content of the gorgonian Eunicea succinea from different locations, a new cembranolide, 12,13-bisepieupalmerin (6), was isolated (structure by X-ray analysis) from specimens from St. Croix, U.S.V.I. 12,13-Bisepieupalmerin possesses the correct stereochemistry to be a biosynthetic precursor for the related cembranolides eunicin (1a) and jeunicin (2). The latter compounds were found to occur with 6 in E. succinea from St. Croix. Eunicin and its acetate (1b) were obtained from a South Caicos collection. E. succinea from St. Croix, U.S.V.I. and South Caicos contain complex mixtures of hydrocarbons in which (-)-germacrene-A, (+)-beta-elemene, (+)-beta-epibourbonene, (+)-beta-copaene, and (+)-alpha-muurolene were identified.