The title compound, C16H20O5, was isolated from the gorgonian coral P.
americana found in the Caribbean zone of the West Indies. The compoun
d belongs to a well known family of sesquiterpenoid lactones. Its stru
cture features a guaiane skeleton incorporating three types of oxygen
functionalities. Thus, the five O atoms that are incorporated in the s
keleton form two epoxy groups, a lactone moiety and an ether link. Thi
s study assigns the relative stereochemistry at the six chiral centers
as 1R,2R,4S,5S,8R,10S.