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.