Triazolium Salts as Lewis Acid Catalysts

We describe a new type of nitrenium-based Lewis acids: tetraaryl-1,2,3-triazolium salts. These were fully characterized by NMR and X-ray crystallography. The Gutmann-Beckett acidity numbers were determined to be up to 35.6, which is high compared to those of previously studied nitrenium salts. These salts catalyze the facile hydrosilylation-deoxygenation of ketones, aldehydes, acetals, alcohols, ethers, and silyl ethers under mild conditions in excellent yields. To our knowledge, this represents a first example of triazolium ions used as Lewis acid catalysts.

Automated summary

A new type of nitrenium-based Lewis acids, tetraaryl-1,2,3-triazolium salts, has been discovered. These compounds exhibit high electrophilicity and catalyze the hydrosilylation-deoxygenation of various organic compounds under mild conditions, showing potential applications as catalysts.