New diterpenes from the Caribbean sponge Epipolasis reiswigi.

Two diterpenes, epipolone (1) and epipolol (3), produced by terpenoid pathways leading to a tricarbocyclic structure with an irregular "head to tail" isoprene configuration, have been isolated from the Caribbean marine sponge Epipolasis reiswigi collected in Puerto Rico. The structures of 1 and 3 were elucidated largely by 1D and 2D NMR methods and chemical conversion.