Polyether triterpenes, marine

The isoprenoids contribute most to the list of structural similarities in the sea and on land. They range from common classes in both ecosystems, such as drimane sesquiterpenes, to rare classes in the sea, such as the trichothecenes (Chart 8.3.11). The similarity in marine and terrestrial polyether triterpenes (Chart 8.3.12) may be seen as convergence toward chemically favored structures, starting from squalene as a biosynthetic precursor. Similar conclusions may apply to polycyclic triterpenes. 

Fernandez JJ, Souto ML, Norte M (2000) Marine Polyether Triterpenes. Nat Prod Rep 17 ... 

R647 Y. Morimoto, Total Synthesis of Marine Halogen-Containing Triterpene Polyethers Using Regioselective 5-Exo and 6-Endo Cyclization and the Stereochemistry , Yuki Gosei Kagaku Kyokaishi, 2012, 70, 154. 

---