Transition-Metal-Free [4+1] Cycloaddition for the Synthesis of 1,2,3-Triazole from α,α-Difluoro-N-Tosylhydrazone and Amine through C-F Bond Cleavage

An efficient synthesis of 1,4-disubstituted and 1,4,5-trisubstituted 1,2,3-triazole from alpha,alpha-difluoro-N-tosylhydrazone and amine through a C-F bond cleavage protocol has been developed. alpha,alpha-Difluoro-N-tosylhydrazone is used as a new reagent, which can transform amines to 1,2,3-triazoles with high efficiency and excellent functional group compatibility without using transition-metal catalysts, azide reagents and oxidants.