Metal-Free C-N- and N-N-Bond Formation: Synthesis of 1,2,3-Triazoles from Ketones, N-Tosylhydrazines, and Amines in One Pot

A novel synthetic approach toward 1,4-disubstituted 1,2,3-triazoles by C-N- and N-N-bond formation has been established under transition-metal-free conditions. Complete control of the regioselectivity was successfully achieved. Commercially available anilines, ketones, and N-tosylhydrazine were treated with molecular iodine in one pot to allow the regioselective generation of 1,4-disubstituted 1,2,3-triazoles in high yields without the use of azides.