The palladium-catalyzed cascade reaction of 2-chloroaryl sulfonates with arylamine and amide nucleophiles provides direct access to N-arylbenzimidazoles. This strategy selectively produces the heterocycles based on chemoselective oxidative addition. 2-Chloroaryl triflates (Tf) produce one regioisomer and the corresponding 2-chloroaryl mesylates (Ms) deliver the other in a selectable manner.
“Cascade Palladium Catalysis: A Predictable and Selectable Regiocontrolled Synthesis of N-Arylbenzimidazoles”, Angew. Chem. Int. Ed., 2013, 52(44), 11624 - 11627.