Synthesis of indenes via aluminum chloride-promoted tandem Friedel–Crafts alkylation of arenes and cinnamaldehydes.

Highlights: [•] Tandem Friedel–Crafts reaction of arenes and cinnamaldehydes was investigated. [•] The cascade reaction affords indenes in good yields. [•] The scope, limitation, and mechanism of the tandem reaction were explored. [•] 1-Phenylindenes generated through a tandem reaction. [•] 1,3-Diphenylindenes generated through a complex cascaded reaction. [Copyright &y& Elsevier]