 Thus, synthetic methods towards substituted aromatic rings are always of great interest to chemists.Traditionally, regioselectivity on the aromatic ring is achieved by the electronic effect of substituents.Taking the well-known Friedel–Craft electrophilic aromatic substitution as example, electron donating groups direct the electrophile to "ortho-/para-"position while electron withdrawing groups direct the electrophile to "meta"-position.