A Copper(II)‐Catalyzed Aza‐Friedel–Crafts Reaction of N‐(2‐Pyridyl)sulfonyl Aldimines: Synthesis of Unsymmetrical Diaryl Amines and Triaryl Methanes

The choice of the (2-pyridyl)sulfonyl moiety as an N-protecting group and Cu(OTf)2/(±)-binap as catalyst system lead to a highly efficient aza-Friedel–Crafts reaction of electron-rich arenes (Ar2-H) and heteroarenes with N-sulfonyl imines. This protocol is also amenable to the synthesis of unsymmetrical triaryl methanes through a second electrophilic aromatic substitution with a different electron-rich arene (Ar3-H; see scheme).