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.