Copper-Catalyzed N-Arylation of Hindered Substrates Under Mild Conditions

A mild, efficient method utilizing a copper-diamine catalyst at room temperature is reported for the coupling of hindered imidazoles with unsubstituted, ortho-substituted, and bis-ortho-substituted boronic acids in good to excellent yields. Aryl halides do not reaction under these conditions permitting sequential N-arylation reactions.