Total syntheses of (+)- and (-)-cacospongionolide B:: New insight into structural requirements for phospholipase A2 inhibition

The first total synthesis of the antiinflammatory marine sponge metabolite (+)-cacospongionolide B has been accomplished in 12 linear steps. The pivotal transformations include a three-step sequence coupling the two main regions of the natural product as well as generating the side chain dihydropyran ring. The activity of the synthetic analogues against bee venom phospholipase A2 suggests that cacospongionolide B has an enantiospecific interaction with the enzyme that is independent of the γ-hydroxybutenolide moiety. Copyright © 2002 American Chemical Society.