Synthesis of Benzo-Fused Cyclic Compounds via Intramolecular Cyclization of Aryltriazenes

Abstract

The rapid and convenient construction of benzo-fused cyclic compounds has attracted significant attention due to their wide applications in various fields. As important building blocks and organic synthons, aryltriazene compounds can be applied in the synthesis of a variety of heterocycles and carbocycles. With promotion by Lewis or Brønsted acids, aryltriazenes are readily transformed into reactive aryl cations which can undergo intramolecular cyclization to form diverse benzo-fused cyclic compounds. This account covers recent developments in the synthesis of benzo-fused cyclic compounds via intramolecular cyclization of aryltriazenes. 1 Introduction 2 Synthesis of Heterocycles via Intramolecular C–N Bond Formation 2.1 Palladium-Catalyzed Regioselective Synthesis of <i>N</i>-Aryl Benzotriazoles 2.2 Brønsted Acid Catalyzed Stereoselective Synthesis of <i>trans</i>-3-Alkenyl Indazoles 2.3 Lewis Acid Promoted Synthesis of Unsymmetrical and Highly Functionalized Carbazoles 3 Synthesis of Heterocycles via Intramolecular C–O Bond Formation 3.1 Lewis Acid Promoted Synthesis of Dibenzofurans and Dihydrobenzofurans 3.2 Lewis Acid Promoted Synthesis of Dibenzopyranones and Coumarins 3.3 Lewis Acid Promoted Synthesis of 2-Hydroxyflavanones 4 Synthesis of Carbocycles via Intramolecular C–C Bond Formation 4.1 Lewis Acid Mediated Synthesis of Unsymmetrical and Functionalized Polycyclic Aromatic Hydrocarbons 4.2 Brønsted Acid Mediated Synthesis of Fluorene Derivatives 5 Conversion into Azides and then into Heterocyclic Compounds 6 Conclusion