I₂/TBPB Mediated Oxidative Reaction of N-Tosylhydrazones with Anilines: Practical Construction of 1,4-Disubstituted 1,2,3-Triazoles under Metal-Free and Azide-Free Conditions

An efficient I2 (20 mol %)/TBPB mediated oxidative formal [4 + 1] cycloaddition of N-tosylhydrazones with anilines via C-N/N-N bond formation and S-N cleavage has been developed. This protocol represents a simple, general, and efficient approach for the construction of 1,2,3-triazoles under metal-free and azide-free conditions by utilizing a catalytic amount of I2.