Synthesis of Indenes and Benzofulvenes via a Palladium-Catalyzed Three-Component Reaction

A palladium-catalyzed three-component domino reaction to access indene derivatives is reported. This reaction proceeds via the sequential formation of three bonds: the first two resulting from inter- and intramolecular carbopalladation and the final bond arising from an attack by a terminating nucleophilic reagent. Modifying the starting tether on the iodoarene led to either indenes or benzofulvenes. Three termination variations were compatible with this sequence, which furnished products in moderate to good yields. The oxabicycle used in this work acts as an acetylene surrogate, which is revealed in a postcatalytic retro-Diels–Alder step. A diastereomerically enriched mixture of oxabicyclic derivatives allowed for preliminary results for the enantioselective synthesis of indenes.