Gold-Catalyzed Synthesis of Tropone and Its Analogues via Oxidative Ring Expansion of Alkynyl Quinols

A new and convenient strategy for the synthesis of functionalized tropone derivatives based on the gold-catalyzed oxidative ring expansion of alkynyl quinols has been developed. The reaction proceeds via gold-catalyzed highly regioselective oxidation followed by 1,2-migration of a vinyl or phenyl group. Extension of this chemistry allows ready access to various seven- or six-membered ring systems such as benzotropones, benzooxepines, phenanthrenes, and quinolin-2­(1H)-ones.