Aplysiadiol from Aplysia dactylomela suggested a key intermediate for a unified biogenesis of regular and irregular marine algal bisabolene-type metabolites

The rearranged compound 1, the regular 2 and 3 and the degraded 4 are novel bisabolene-type metabolites that along with the known compounds caespitol, 8-acetylcaespitol, caespitane, caespitenone, laucapyranoid A, and furocaespitane have been isolated from the sea hare Aplysia dactylomela. The structures of these compounds were determined on the basis of spectroscopic evidence. The irregular network of 1 suggested that the halogenated epoxide 6 is a key intermediate for a unified biogenetic pathway of naturally occurring marine algal bisabolene-type metabolites.