Bis-arylation of phenylene-bridged bis-azolium salts and tetra-arylation of bis-azoles to access symmetrical and unsymmetrical CCC-aNHC pincer ligand precursors

Copper-mediated methodologies for the arylation of bis-azolium salts and bis-azoles are efficient pathways to access symmetrical and unsymmetrical N -heterocyclic carbene precursors. The arylation of bis-azolium salts with various aryl halides was achieved in moderate yields to furnish numerous C2-arylated bis-azolium salts. Access of C2-arylated bis-azolium salts from bis-azoles was also achieved in a single pot domino reaction via the use of iodonium salts as embedded electrophiles. The latter methodology utilizes the aryl iodide byproduct from the N-arylation step for the C-H activation step to mitigate waste and the need to recycle. We also demonstrated the use of these azolium salts in metalation and found success in obtaining metal complexes containing abnormal N -heterocyclic carbenes. • Cu-catalyzed C-H functionalization of bis-azolium salts • Cu-catalyzed tetra-arylation of bis-azoles • Synthesis of abnormal NHC pincer complexes of Zr and Pt