One-pot synthesis of [1,2,4]Triazolo[1,5-a]pyridines from azines and benzylidenemalononitriles via copper-catalyzed tandem cyclization

A simple and efficient copper-catalyzed tandem radical cyclization reaction has been discovered for the synthesis of triaryl [1,2,4]triazolo[1,5-a]pyridines from easily accessible azines and benzylidenmalononitriles. The new transformation involves multiple CH/CC bonds cleavage and CC/CN bonds formation, with extrusion of gaseous hydrogen and methane. A wide variety of substrates with different functional groups could be converted into the corresponding products in good yields. The fused heterocycles have strong blue fluorescence with large Strokes shifts and high quantum yields.