Synthesis of 3-Pyrazolyl-1,2,4-Triazoles via One-Pot Multicomponent Reaction in Phosphoric Acid

A high-yielding synthetic route towards pyrazolyl-[1,2,4]triazole derivatives has been developed via one-pot multicomponent reaction of polyfunctionalized triazoles, DMF–DMA, acetophenone, ethyl cyanoacetate, and/or 3-oxo-3-phenylpropanenitrile in ortho-phosphoric acid (85%). In the same manner, a new series of 2-triazolyl-tetrahydro-indazol-4-ones and pyrazolo[3,4-d]pyrimidines has been synthesized by reaction of triazoles, DMF–DMA and 1,3-cyclohexanediones and/or barbituric acid, respectively. The same products were prepared a classical manner via reaction of triazoles with the corresponding enaminones in ortho-phosphoric acid (85%).