Recent Progress in Gold-Catalyzed Reactions of Alkynes for the Construction of Indole Frameworks

Indole heterocycles hold an important position in chemical landscape because of their prominence in natural products and pharmaceuticals. Consequently, development of new and efficient strategies to access indole scaffold are of continuous interest. For the past few years, gold-catalyzed activation of alkyne has emerged as a powerful strategy for constructing the heterocyclic skeleton. The present review highlights recent advances (2018-2023) toward synthesis of indole skeletons via gold-catalyzed annulations of alkynes. A variety of alkynes, such as, ynamides, azido alkynes, ortho-alkynyl anilines, propargylic alcohols, ortho-alkynyl phenylimines, and miscellaneous alkynes are employed affording various indole architectures under gold catalysis. Moreover, mechanisms are included in most of the cases for better understanding of the reaction pathway.