Recent Advances in the Regioselective Synthesis of Indoles via C-H Activation/Functionalization

Indole is an important heterocyclic motif that occurs ubiquitously in bioactive natural products and pharmaceuticals. Immense efforts have been devoted to the synthesis of indoles starting from the Fisher indole synthesis to the recently developed C-H activation/functionalization-based methods. Herein, we have reviewed the progress made on the regioselective synthesis of functionalized indoles, including 2-substituted, 3-substituted and 2,3-disusbstituted indoles, since the year 2010. 1 Introduction 2 Metal-Catalyzed Synthesis of 2-Substituted Indoles 3 Metal-Catalyzed Synthesis of 3-Substituted Indoles 4 Metal-Free Synthesis of 3-Substituted Indoles 5 Metal-Catalyzed 2,3-Disubstituted Indole Synthesis 5.1 Metal-Catalyzed Intramolecular 2,3-Disubstituted Indole Synthesis 5.2 Metal-Catalyzed Intermolecular 2,3-Disubstituted Indole Synthesis 6 Metal-Free 2,3-Disubstituted Indole Synthesis 6.1 N-Protected 2,3-Disubstituted Indole Synthesis 6.2 N-Unprotected 2,3-Disubstituted Indole Synthesis 7 Applications 8 Summary and Outlook