Sequential One-Pot Synthesis Of 3-Arylbenzofurans From N-Tosylhydrazones And Bromophenol Derivatives

A divergent and efficient one-pot sequence allowing direct access to 3-arylbenzofuran derivatives has been developed. The process, involving N-tosylhydrazones and bromophenols, proceeds via a palladium-catalyzed Barluenga-Valdes cross-coupling, followed by an aerobic, copper-catalyzed, radical cyclization to form Csp(2)-Csp(2) and O-Csp(2) bonds. 3-Arylated benzofurans bearing various substituents were obtained with good to excellent yields (up to 90%). Mechanistic investigation strongly supports a radical process for the cyclization step.