Air-oxidized products of multi-component reactions between 3-amino-1,2,4-triazole, aromatic aldehydes and isonitriles

The Groebke-type multi-component reaction (MCR) between 3-amino-1,2,4-triazole, aromatic aldehydes and isonitriles has been studied from the viewpoint of convenient generation of combinatorial arrays of imidazo[1,2-b][1,2,4]triazoles. However, it was established that the desired heterocyclic structures can be produced in moderate to good yields in an oxidized form, when benzylic isonitriles are used. Oxidation occurred at the benzylic position to produce N-alkylidene-4H-imidazo[1,2-b][1,2,4]triazol-6-amines that proved to be unusually stable towards acid hydrolysis and reduction. The presence of an easily oxidized benzylic position in the target structures is thought to be the prerequisite for successful Groebke-type MCR of 3-amino-1,2,4-triazole.