Transition-Metal-Free Regioselective Construction of Cyano- and Phosphonyl Tetrazole Derivatives

A Brønsted base-promoted, transition-metal-free [3 + 2] cycloaddition for the regioselective synthesis of cyano- and phosphonyl-substituted tetrazoles is reported. Compared to readily decomposing diazonium salts, the use of arylazo sulfones not only enhances safety but also avoids the need for precious metal catalysts. Arylazo sulfones exhibit excellent reactivity, whereas other commonly used azo compounds are nearly ineffective. Modification of natural products, synthesis of dual tetrazoles, gram-scale reactions, and investigations into product transformation further highlight the promising applications.