Cu(OTf)2-Mediated Cross-Coupling of Nitriles and N-Heterocycles with Arylboronic Acids to Generate Nitrilium and Pyridinium Products**

Metal-catalyzed C-N cross-coupling generally forms C-N bonds by reductive elimination from metal complexes bearing covalent C- and N-ligands. We have identified a Cu-mediated C-N cross-coupling that uses a dative N-ligand in the bond-forming event, which, in contrast to conventional methods, generates reactive cationic products. Mechanistic studies suggest the process operates via transmetalation of an aryl organoboron to a Cu-II complex bearing neutral N-ligands, such as nitriles or N-heterocycles. Subsequent generation of a putative Cu-III complex enables the oxidative C-N coupling to take place, delivering nitrilium intermediates and pyridinium products. The reaction is general for a range of N(sp) and N(sp(2)) precursors and can be applied to drug synthesis and late-stage N-arylation, and the limitations in the methodology are mechanistically evidenced.

Automated summary

A novel Cu-mediated C-N cross-coupling reaction has been identified in this study, which can be applied to drug synthesis and late-stage N-arylation. Mechanistic studies have provided evidence for the limitations in the methodology.