Gold-Catalyzed Functionalization Reactions of Indole

This review summarizes the progress achieved in the last fifteen years by application of homogeneous gold catalysis in the field of indole functionalization. Several electrophilic species obtained through gold-catalyzed -activation have in fact been found to react with the nucleophilic positions of indole, thus allowing its efficient manipulation. In order to furnish a complete and clear overview on the role of the catalyst, the review is organized from the perspective of the gold-activated substrate that is reacting with the indole. In addition, in view of the ability of gold to catalyze tandem and cascade reactions, a separate section describes tandem/cascade protocols useful for the synthesis of complex polycyclic indole derivatives. Finally, gold catalysis has also been employed for the synthesis of indole-based natural products. For this reason, a dedicated section collects all the work in which the key step to obtain these complex indoles is represented by a gold-catalyzed reaction.