Highly substituted oxabicyclic derivatives from furan: synthesis of (±)-platensimycin.

A stereocontrolled approach to a key platensimycin intermediate was achieved from a commercially available furylcarboxylate. Key to our approach is the highly efficient formal [4 + 3] cyclocondensation of a substituted furan with tetrabromocyclopropene along with an intramolecular γ-alkylation to construct the final ring of the caged intermediate.