Silver Effect in Regiodivergent Gold-Catalyzed Hydroaminations

We report a silver-induced switching of regioselectivity in gold-catalyzed reactions, and we provide mechanistic evidence to suggest a true silver effect: that is, one that is implicated in the catalytic process itself, via sigma-gold pi-silver acetylides. These results are of significance because they clearly show that the use of silver as halide abstractors in gold-catalyzed reactions may result in silver effects when terminal alkyne substrates are involved.