A total synthesis of brevenal is described. The pentacyclic ether core was constructed by the intramolecularallylation of α-acetoxyether and subsequentring-closingmetathesis. Both of the diene side chains were introduced by Wittig olefination and a Horner−Wadsworth−Emmons reaction, respectively, in a highly stereoselective manner.
The convergent total synthesis of brevenal, a non-toxic brevetoxin antagonist, has been achieved. The ABC ring segment and the E ring precursor were connected by the intramolecularallylation followed by ring-closingmetathesis to furnish the pentacyclic ether compound. An alternative route to the key synthetic intermediate, a pentacyclic ether core, was also examined. The right- and left-hand side