Ferric chloride-catalyzed C-N bond cleavage for the cyclization of arylallenes leading to polysubstituted indenes

A range of arylallenes undergo carbocation-initiated cyclization reaction with N-benzylic and N-allylic sulfonamides in the presence of 10 mol% ferric chloride to give structurally diverse polysubstituted indenes in good yields with extremely high regioselectivity.