Golden duality: Tetrazoles are formed by the reaction of alkynes with TMSN3 (TMS=trimethylsilyl) in the presence of iPrOH and the gold(I) catalyst [JohnPhosAu(MeCN)]SbF6. In this transformation gold plays a dual role, first activating the alkyne and then generating a Brønsted acid in situ.
![Gold-Catalyzed Synthesis of Tetrazoles from Alkynes by C-C Bond Cleavage](https://www.iciq.org/wp-content/uploads/2014/03/Gold-Catalyzed-Synthesis_echavarren20ACIE.gif)