Synthetic approaches towards the marine alkyl purines.

Agelasines, asmarines and related compounds are natural products with a hybrid terpene-purine structure isolated from numerous genera of sponges (Agela sp, Raspailia sp). Nuttingins and malonganenones are tetraprenylated purine alkaloids from gordonian (Eplexura sp, Leptogorgia sp). Some of these alkaloids displayed broad spectrum activity including cytotoxic activity against several cancer cells. The review summarizes the synthesis of mono- or bi-cyclic diterpenoids usually having a 9-methyladenine moiety.