N‐Heterocyclic Carbene–Palladium Complexes [(NHC)Pd(acac)Cl]: Improved Synthesis and Catalytic Activity in Large‐Scale Cross‐Coupling Reactions

Abstract

Abstract From two commercially available starting materials, improved one‐step, multigram‐scale syntheses of [(IPr)Pd(acac)Cl] [IPr= N , N′ ‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene; acac=acetylacetonate] and [(IMes)Pd(acac)Cl] [IMes= N , N′ ‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene] are described. The catalytic activity of both complexes in cross‐coupling reactions has been examined. The most active pre‐catalyst, [(IPr)Pd(acac)Cl], has allowed for efficient large‐scale (10 mmol) Buchwald–Hartwig and α‐ketone arylation reactions to be carried out.