Copper Powder Catalyzed Direct Ring‐Opening Arylation of Benzazoles with Aryl Iodides in Polyethylene Glycol
The expedient and efficient copper powder catalyzed direct ring-opening arylation of benzazoles with aryl iodides in polyethylene glycol that proceeds in the absence of an added ligand has been developed. The protocol provides facile access to 2-(arylthio)anilines and 2-phenoxyanilines in high yields with a wide tolerance of functional groups. Transmission electron microscopy confirmed that the active catalyst results from the in situ generation of copper nanoparticles under standard reaction conditions, which is an alternative avenue to develop a highly effective metallic copper catalyst. Moreover, the catalytic system can be recycled up to six times.