Stable Cyclic (Alkyl)(Amino)Carbenes as Rigid or Flexible, Bulky, Electron‐Rich Ligands for Transition‐Metal Catalysts: A Quaternary Carbon Atom Makes the Difference

Like NHCs? Not quite: Cyclic (alkyl)(amino)carbenes (CAACs) are strong σ-donors and have steric environments that differ dramatically from those of bulky, electron-rich phosphines (A) and cyclic diaminocarbenes (B). These readily available carbenes are desirable ligands for catalysis, as illustrated by the first palladium-mediated α-arylation of ketones and aldehydes with non-activated aryl chlorides at ambient temperature.