The First General Enantioselective Catalytic Diels−Alder Reaction with Simple α,β-Unsaturated Ketones

The first general approach to enantioselective catalysis of the Diels−Alder reaction with simple ketone dienophiles has been accomplished. The use of iminium catalysis has enabled enantioselective access to a fundamental Diels−Alder reaction variant that has previously been unavailable using chiral Lewis acid catalysis. A new chiral amine catalyst has been developed that allows a variety of monodentate cyclic and acyclic ketones to successfully participate in enantioselective [4 + 2] cycloadditions. A wide spectrum of cyclic and acyclic diene substrates can also be accommodated in this new organocatalytic transformation. A computational model is provided that is in accord with the sense of enantioinduction observed for all reactions conducted during the course of this study.