Elisapterane, elisabane, cumbiane or colombiane diterpenoids

Diterpenoids with a structure based on either the elisapterane, elisabane, cumbiane or colombiane skeleton. They derive from serrulatane. Elisapterane is a tetracyclic compound formed by C10-C15 cyclization of elisabethane. Elisabane (nor-elisapterane) results from the loss of the C17 carbon atom of elisapterane. Cumbiane is formed by C10-C16 cyclization of the elisabethane carbon skeleton. Meanwhile, the cleavage of the C15-C16 bond of cumbiane yields the seco-cumbiane skeleton. Colombiane is also a tetracyclic skeleton arises from the C12-C2 cyclization of the elisabethane skeleton.