A Concise Assembly of Electron‐Deficient 2,4‐Dienes and 2,4‐Dienals: Regio‐ and Stereoselective exo‐Diels–Alder and Redox Reactions through Sequential Amine and Carbene Catalysis

Ideal relay catalysis: A γ,δ-regioselective anomalous exo-Diels–Alder reaction with electron-deficient β-substituted 2,4-dienes and 2,4-dienals has been developed by using trienamine activation. The resulting multifunctional cycloadducts contain perfectly positioned functional groups, thereby facilitating a 1,5-hydride transfer from the C–H group of an aldehyde to an activated alkene under sequential catalysis of a carbene (see scheme).