A Concerted Catalytic System for Sonogashira Coupling Reactions: Combination of N‐Heterocyclic Carbene Palladium and Copper Complexes

Abstract Robust acenaphthoimidazolylidene palladium complexes have been demonstrated as highly efficient and general catalysts for Sonogashira cross‐coupling reactions in excellent yields even at 0.01 mol % catalyst loadings in combination with 1 mol % IPr–Cu under mild reaction conditions. The outcomes highlight that, along with the steric bulky aspects, σ‐donor properties of the NHC ligands are also crucial to accelerate the transformations.