Tandem C–N coupling/Boulton–Katritzky rearrangement reactions of 3-aminoisoxazoles or 1,2,4-oxadiazol-3-amines with 2-pyridyl trifluoromethanesulfonate: a rapid access to [1,2,4]triazolo[1,5-a]pyridines

An efficient and convenient synthesis of functionalized [1,2,4]triazolo[1,5-a]pyridine derivatives is presented. The protocol involves a palladium catalyzed tandem C–N coupling/Boulton–Katritzky rearrangement process of 3-aminoisoxazoles or 1,2,4-oxadiazol-3-amines with 2-pyridyl trifluoromethanesulfonate. This protocol features readily available starting materials and could also be applied to the synthesis of leishmania CRK3 inhibitors.