Synthesis of Indenes via Bronsted Acid Catalyzed Cyclization of Diaryl- and Alkyl Aryl-1,3-dienes

Substituted indenes can be synthesized via the Bronsted acid catalyzed cyclization of diaryl- and alkyl aryl-1,3-dienes. In this approach, treatment of symmetric or unsymmetric diaryl- and alkyl aryl-1,3-dienes with a catalytic amount of trifluoromethanesulfonic acid gives a variety of indene derivatives in good to excellent yields under mild conditions.