Highly enantioselective γ-amination by N-heterocyclic carbene catalyzed [4+2] annulation of oxidized enals and azodicarboxylates.

γ-Amination: The title reaction was developed to give the corresponding dihydropyridazinones in good yields with excellent enantioselectivities (see scheme; Mes=2,4,6-trimethylphenyl). The annulation reaction worked well for γ-aryl, γ-alkyl, or γ-alkenyl oxidized enals. Highly enantiopure tetrahydropyridazinones and γ-amino acid derivatives could be easily prepared by chemical transformations of the resulting dihydropyridazinones.