General procedure for the Ni-catalyzed cross-electrophile coupling of pyridinium salts with aryl iodides

An oven-dried 25-ml Schlenk tube equipped with a stir bar was charged with redox-active pyridinium salts 1 (0.2 mmol, 1.0 equiv), NiBr2•diglyme (0.02 mmol), 2,2′:6′,2″-terpyridine (0.02 mmol), zinc flake (−325 mesh, 99.9%) (0.5 mmol), and aryl iodide (0.3 mmol) (if solid). The tube was then evacuated and back-filled with argon (three times). Aryl iodide (0.3 mmol; if liquid) and anhydrous DMF (2 ml) were added under argon. The resulting mixture was allowed to stir for 8 hours under argon atmosphere at 60°C (oil bath). The reaction mixture was quenched with 1 M HCl and extracted with EtOAc. The organic layer was washed with water and brine and dried over Na2SO4. The organic layer was concentrated under vacuum by rotary evaporator in a water bath at 45°C. Flash column chromatography or preparative TLC provided the product.