Copper–Catalyzed Construction of the Indole Core: Recent Advancements

Indoles are one of the most important heterocycles because of their widespread occurrence in bioactive natural products, synthetic drugs and organic materials. Therefore, development of efficient strategies for synthesizing functionalized indoles has been of great importance in organic synthesis. Copper, being a transition metal, meet the goal due to its low toxicity, high catalytic activity and cost‐effectiveness. In this review, we focus on last five year (2019–2023) advancement in copper‐catalyzed annulations for the construction of indole core involving various N‐containing substrates, which include anilines, o‐alkynylanilines, o‐aminophenylpropynols, o‐alkynylnitroarenes, o‐nitrochalcones, azidoalkynes, isonitriles, nitriles, enamines, imines, etc. Mechanistic aspects of the reactions have also been highlighted for better understanding of the reaction pathways.