An N-Heterocyclic Carbene-Mediated, Enantioselective and Multicatalytic Strategy to Access Dihydropyranones in a Sequential Three-Component One-Pot Reaction.

The multicatalytic generation of 3,5,6-trisubstituted 3,4-dihydropyranones with high enantioselectivity using a highly convergent strategy starting from commercially available precursors is reported. The operationally simple three-step, one-pot protocol merges H-bond and NHC catalysis to provide crucial, reactive β-unsubstituted enones from nitroalkenes as latent 1,2-biselectrophiles. These intermediates are directly funneled into a further NHC-catalyzed formal hetero-Diels-Alder reaction to deliver manifold chiral C(4)-unsubstituted dihydropyranones (typical ee >98%), allowing aliphatic and heteroaromatic substituents and hence expanding the scope of this Michael addition/lactonization.