The cinnamates having an ortho-formyl group can potentially form vinylogous iminium ion species under the catalysis of chiral amines, which facilitates the Diels–Alder cycloaddition reaction with the concurrently generated trienamines between dienals and amine catalysts in a regioselectivity umpolung manner. A cascade intramolecular aldol reaction was followed, finally furnishing polyhydrophenanthrene frameworks with excellent diastereo- and enantioselectivity.

Under the catalysis of Lewis bases, cyclic enones bearing an α-(2-furyl) motif can undergo remote Friedel–Crafts reaction with electrophilic reagents via a HOMO-activation strategy, proceeding in a formal vinylogous Rauhut–Currier or Morita–Baylis–Hillman-type reaction pattern. Moreover, even less reactive α-(2-benzofuranyl)-substituted cyclopeten-2-ones can be similarly HOMO-raised and furnish [4 + 2] products with alkylidenemalononitriles in a cascade Friedel–Crafts/Michael addition process.

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