Lewis Acid Catalyzed Ring-Opening Intramolecular Friedel−Crafts Alkylation of Methylenecyclopropane 1,1-Diesters

The first Friedel−Crafts reaction initiated by the direct generation of a carbocation at the C3 position of MCP 1,1-diesters through distal-bond cleavage was presented. The described method supplied a new synthetic strategy to prepare indene and hydronaphthalene derivatives in moderate to excellent yields under mild conditions.