title: Dienamine catalysis: organocatalytic asymmetric gamma-amination of alpha,beta-unsaturated aldehydes.
abstract: A new concept in organocatalysis is presented, the direct asymmetric gamma-functionalization of alpha,beta-unsaturated aldehydes. We disclose that secondary amines can invert the usual reactivity of alpha,beta-unsaturated aldehydes, enabling a direct gamma-amination of the carbonyl compound using azodicarboxylates as the electrophilic nitrogen-source. The scope of the reaction is demonstrated for the enantioselective gamma-amination of different alpha,beta-unsaturated aldehydes, giving the products in moderate to good yields and with high enantioselectivities up to 93% ee. Experimental investigations and DFT calculations indicate that the reaction might proceed as a hetero-Diels-Alder cycloaddition reaction. Such a mechanism can explain the "unexpected" stereochemical outcome of the reaction.
authors.affiliation: The Danish National Research Foundation: Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Bertelsen
authors.forename: Mauro
authors.initials: M
authors.lastname: Marigo
authors.forename: Sebastian
authors.initials: S
authors.lastname: Brandes
authors.forename: Peter
authors.initials: P
authors.lastname: Dinér
authors.forename: Karl Anker
authors.initials: KA
authors.lastname: Jørgensen