A Concise Route to the Strongylophorines.

An efficient eight-step semisynthesis of strongylophorine-2 from the abundant building block isocupressic acid is reported. The route represents the first synthetic entry into this class of natural products and provides access to six additional family members. A novel iron(III)-mediated rearrangement-cyclization cascade and a directed photochemical sp(3) C-H δ-lactonization are the key transformations that enable concise assembly of these bioactive polycyclic meroterpenoids.