Practical one-pot, three-component synthesis of N-heterocyclic carbene (NHC) ligated palladacycles derived from n,n-dimethylbenzylamine

Further explorations of the catalytic potential of N-heterocyclic carbene (NHC) ligated palladacycles as catalysts for Pd-mediated transformations have been hampered by the lack of general and practical methods for their synthesis. In this work, we describe a novel, practical approach to NHC-ligated palladacycles by a three-component, one-pot reaction of imidazolium salts, PdCl², and N,N-dimethyl-benzylamine in the presence of excess K ²CO³ under reflux in reagent-grade acetonitrile in air. 1,3-Diarylimidazolium salts afford the corresponding NHC-Pd(dmba)Cl (dmba = N,N-dimethylbenzy-lamine-K²N,C) complexes in >80% yield. The conversion of 1,3-diary1-4,5-dihydroimidazolium and 1,3-dialkylimidazolium or benzimidazolium salts requires the use of stronger base (Cs₂CO ₃) and/or higher temperature (100 °C). The Pd-bound chloride anion can be exchanged with silver salts or sodium salts. The NHC-palladacycle adducts have been characterized by single-crystal X-ray crystallography.