Development of a Regioselective N-Methylation of (Benz)imidazoles Providing the More Sterically Hindered Isomer

An efficient and highly regioselective N-methylation of (NH)-(benz)imidazoles furnishing the sterically more hindered, less stable, and usually minor regioisomer has been developed. The methodology involves very mild reaction conditions and tolerates a wide range of functional groups.