Elements of Regiocontrol in the Direct Heteroarylation of Indoles/Pyrroles: Synthesis of Bi- and Fused Polycyclic Heteroarenes by Twofold or Tandem Fourfold CH Activation

Cross‐coupling: The “chelation‐directed control” and “catalytic‐system‐based control” strategies effectively switch the C2/C3‐site selectivity in the heteroarylation of indoles and pyrroles with N‐heteroarenes by a palladium‐catalyzed twofold CH activation to form biheteroarenes and are further extended to the synthesis of complex fused tri‐ and tetracyclic heteroarenes by a tandem fourfold CH activation (see scheme).