Metal-Free Photocatalyzed Cross Coupling of Bromoheteroarenes with Pyrroles

The excited radical anion of rhodamine 6G reduces heteroaryl bromides and chlorides to generate heteroaryl radicals that were successively trapped by pyrroles for the synthesis of heteroaromatic biaryls in moderate to excellent yields. The synthetically important photoredox catalytic C–H heteroarylation reaction works for a broad range of brominated electron-rich heteroarenes and chlorinated heteroarenes bearing electron withdrawing groups. In addition, this methodology was applied to the formal synthesis of a benzimidazole derivative II with interesting pharmacological properties.