Combining iminium and supramolecular catalysis for the [4 + 2] cycloaddition of -cinnamaldehydes.

Herein we describe a method for combining supramolecular catalysis with imininum-based organocatalysis in the Diels-Alder cycloaddition reaction. Both supramolecular host and L-proline are required for the reaction to occur, implying that encapsulation of the substrates and co-catalyst are necessary for the reaction to occur. We explore the substrate scope for a variety of -cinnamaldehydes and dienes.