Lewis Acid-Catalyzed Rearrangement of Multi-Substituted Arylvinylidenecyclopropanes

An interesting rearrangement of arylvinylidenecyclopropanes having three substituents at the 1- and 2-positions of the corresponding cyclopropane catalyzed by Lewis acids to give 6aH-benzo[c]fluorine derivatives via a double intramolecular Friedel−Crafts reaction or to give an indene derivative via an intramolecular Friedel−Crafts reaction is described.