Copper-Catalyzed Enantioselective Hetero-Diels–Alder Reaction of Danishefsky’s Diene with Glyoxals

The highly enantioselective hetero-Diels–Alder reaction of Danishefsky’s diene with glyoxals was developed by virtue of a readily accessible chiral copper catalyst. This efficient transformation provided a facile and scalable access to a wide range of biologically active dihydropyrones with a high level of enantioselectivities. Moreover, the substrate scope of this reaction could be extended to isatins with this catalytic system. More importantly, the mechanism involved in this reaction was proposed on the basis of the unambiguous structures of intermediates.