One‐Step Access to Heteroatom‐Functionalized Imidazol(in)ium Salts

Abstract

AbstractImidazolium salts have ubiquitous applications in energy research, catalysis, materials and medicinal sciences. Here, we report a new strategy for the synthesis of diverse heteroatom‐functionalized imidazolium and imidazolinium salts from easily available 1,4‐diaza‐1,3‐butadienes in one step. The strategy relies on a discovered family of unprecedented nucleophilic addition/cyclization reactions with trialkyl orthoformates and heteroatomic nucleophiles. To probe general areas of application, synthesized N‐heterocyclic carbene (NHC) precursors were feasible for direct metallation to give functionalized M/carbene complexes (M=Pd, Ni, Cu, Ag, Au), which were isolated in individual form. The utility of the chloromethyl function for the postmodification of the synthesized salts and Pd/carbene complexes was demonstrated. The obtained complexes and imidazolium salts demonstrated good activities in Pd‐ or Ni‐catalyzed model cross‐coupling and C−H activation reactions.