A base-promoted tandem S N Ar/Boulton−Katritzky rearrangement is developed. It offers a simple and straightforward method for the formation of functionalized [1,2,4]triazolo [1,5-a]pyridines from 1,2,4-oxadiazol-3-amines or 3-aminoisoxazoles with 2-fluoropyridines.[1,2,4]Triazolo[1,5-a]pyridine is one of the most privileged skeletons and has been extensively found in many bioactive natural products, drug candidates, and pharmaceuticals (Figure 1). 1 Due to their biological importance, [1,2,4]triazolo[1,5a]pyridine compounds have attracted a great deal of interest from the synthetic community. Many elegant approaches have been developed and applied for their syntheses. Such structures are generally acquired through metal-mediated or metal-free oxidative cyclization from N-(2-pyridyl) amidines and dehydrative cyclization from N′-hydroxy-N-formimidamides. 2,3 Despite this success, exploring more straightforward and practical methods for the construction of this class of biologically important structures is still highly desirable.

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