A facile method for Ni/NHC catalyzed C–H alkylation and alkenylation of heteroarenes with alkenes and internal alkynes using air-tolerant nickelocene, sodium formate and NHC·HCl salts for in situ catalyst generation has been developed.

Fundamental differences in the behavior of Pd/NHC and Ni/NHC catalytic systems in ketones α-arylation were elucidated and exploited.

Imidazolium 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 CÀ H activation reactions.

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An efficient method for the C(2)−H arylation of (benz)imidazoles and (benz)oxazoles with aryl chlorides and aryl bromides under Ni/NHC catalysis has been developed. The main benefit of the method is the in situ generation of active Ni/NHC complexes from the air‐tolerant bench‐stable precursors NiCl2Py2, IMes⋅HCl, and potassium tert‐butoxide, which plays a dual role as base and Ni(II) to Ni(0) reductant. The approach represents a user‐friendly alternative for procedures relying on the use of toxic phosphine ligands or unstable air‐sensitive Ni(cod)2. The concept highlighted in the present study shows that mapping a competitive picture of catalyst dynamics and revealing the competitive processes towards the destruction and stabilization of catalytically active species enables a highly efficient catalytic system to be built under simple conditions.