Lewis Acid Catalyzed Reaction of Arylvinylidenecyclopropanes with Acetals: A Facile Synthetic Protocol for the Preparation of Indene Derivatives

Abstract

[Structure: see text] A number of highly substituted indene derivatives have been prepared in good yields by the reactions of arylvinylidenecyclopropanes 1 with acetals 2 in the presence of Lewis acid under mild conditions. The reaction is believed to proceed via regioselective addition of oxonium intermediate to arylvinylidenecyclopropane and the subsequent intramolecular Friedel-Crafts reaction.