Optimal Balance in the Catalyst Dynamics Enables C(2)-H Arylation of (Benz)imidazoles and (Benz)oxazoles by an In Situ-Generated Ni/NHC System

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 center dot 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.