Construction of [6-5-5-6-6] Pentacyclic Skeleton via a Phosphine-Catalyzed Domino Reaction and Mechanism Study.

A novel phosphine-promoted domino reaction between thioaurone or aurone derivatives and MBH carbonate is described. A wide range of [6-5-5-6-6] pentacyclic compounds was prepared efficiently. Interestingly, the stereoselectivity was affected by the sulfur or oxygen atom in the substrates.