Synergistic N‐Heterocyclic Carbene/Palladium‐Catalyzed Umpolung 1,4‐Addition of Aryl Iodides to Enals

An umpolung 1,4‐addition of aryl iodides to enals promoted by cooperative (terpy)Pd/NHC catalysis was developed that generates various bioactive β,β‐diaryl propanoate derivatives. This system is not only the first reported palladium‐catalyzed arylation of NHC‐bound homoenolates but also expands the scope of NHC‐induced umpolung transformations. A diverse array of functional groups such as esters, nitriles, alcohols, and heterocycles are tolerated under the mild conditions. This method also circumvents the use of moisture‐sensitive organometallic reagents. It takes two: Synergistic catalysis between NHC and palladium catalysts enables the conjugate addition of aryl iodides to enals under redox‐neutral conditions. This method circumvents the use of moisture‐sensitive organometallic reagents, and a diverse array of functional groups such as esters, nitriles, alcohols, and heterocycles are tolerated.