Gold-Catalyzed Synthesis of 3-Arylindoles via Annulation of Nitrosoarenes and Alkynes

We have successfully developed a Au-catalyzed annulation method to produce substituted 3-arylindoles from the reaction of nitrosoarenes with arylsubstituted acetylenes under reductive conditions using sodium borohydride. Terminal alkynes reacted better than non-terminal ones with various substituted nitrosoarenes to afford regioselective 3-substituted indoles. This method is simple and straightforward and can be applied successfully to the synthesis of highly substituted indoles.