Regioselectivity Umpolung in Asymmetric Diels–Alder Reaction of <i>ortho</i>-Formyl-Substituted Cinnamates and Dienals via Double Aminocatalysis

Abstract

-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.