Abstract A series of 1, 2, 4-triazolopyridines have been prepared by oxidative intramolecular cyclization of heterocyclic hydrazones with [bis (trifluroacetoxy) iodo] benzene. General applicability of this simple transformation was confirmed by synthesis of 1, 2, 4-triazolo [4, 3- a] pyridine. The advantages of this protocol are the nontoxicity of catalyst and shorter reaction time to obtain good preparative yield.
[Thiel, Oliver R.; Achmatowicz, Michal M.; Reichelt, Andreas; Larsen, Robert D. Angewandte Chemie - International Edition, 2010 , vol. 49, # 45 p. 8395 - 8398]