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

•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.

A series of substituted indenes were synthesized from arenes and cinnamaldehydes via aluminum chloride-promoted tandem Friedel–Crafts alkylation. The scope and limitation of the tandem reaction were explored. A plausible reaction mechanism is also discussed. This approach provides a convenient method for the synthesis of indene derivatives using a readily available and low cost Lewis acid and starting materials.

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