Proposed Reaction Mechanism
(A) Plausible reaction pathway for the defluorinative Friedel-Crafts cyclization and defluorinative elimination of gem-difluoroalkanes (1).
(B) To rule out the possibility of affording spirobiindanes 2 via the intermediate of monofluoroalkene 3.
(C) Proposed reaction mechanism for the hydrogen-bonding-induced intramolecular Friedel-Crafts reaction of benzylic monofluoride 4q.