Copper‐Catalyzed Regioselective Reaction for Arylselenation of Unprotected Pyrazoles Using Selenium Powder

Abstract A new and convenient Cu‐catalyzed three‐component reaction of N‐unsubstituted pyrazoles with Se powder and aryl iodides has been established. The protocol presents a broad substrate scope, good functional group tolerance, and high regioselectivity. The utility of this procedure is further established by gram‐scale synthesis as well as the diversified transformations of 4‐organylselanyl‐1 H ‐pyrazoles to useful compounds.