Studies directed toward the total synthesis of salvilenone

Abstract

Model studies on the total synthesis of salvilenone, a phenalenone diterpene found in the roots of Salvia miltiorrhiza Bunge, are reported via a double annulation strategy. The key steps in the proposed synthesis involve a regiocontrolled benzannulation involving the photochemical Wolff rearrangement of an a-diazo ketone and an alkoxy acetylene moiety which assembles an aromatic ring in one step from acyclic precursors followed by an intramolecular [4 + 2] cycloaddition of a conjugated enyne and benzyne intermediate.