External oxidants in gold-catalyzed cross-coupling reactions

Au(I)-catalyzed reactions have emerged as an important tool for various organic transformations in the past decade, especially for cross-coupling reactions. However, the exceptionally high reduction potential value of the Au(I)|Au(III) redox couple may act as an obstacle in its development. However, using external mild oxidants in the gold-catalyzed reactions solves this problem effectively. This review gives an overview of different types of oxidants employed in various gold-catalyzed cross-coupling reactions. Such oxidants function via two general mechanistic pathways in which either the oxidation state of the Au(I) atom changes temporarily in the catalytic cycle or it remains intact during the whole process. Therefore, in this article, we also discuss such catalytic reactions from a mechanistic point of view and present the mechanistic proposals given by the authors themselves.