Synthesis of New Substituted Pyridopyrazolotriazines

Abstract

Pyrazolo[3,4- b ]pyridinediazonium chlorides react with a variety of active methylenecontaining reagents (e. g., cyanoacetic acid arylidenehydrazide derivatives) to afford the corresponding 3-hydrazonopyrazolo[3,4- b ]pyridine derivatives. The diazonium chlorides react with N '-acyl-2-cyanoacetohydrazide derivatives to give corresponding 3-hydrazonopyrazolopyridine derivatives. The latter affords corresponding 3-hydrazonopyrazolo[3,4- b ]pyridine derivatives on reflux in acetic acid. Diazocoupling of 2,4-dimethylpyrazolo[3,4- b ]pyridinediazonium chloride with ketoester, e. g. , ethyl benzoylacetate is followed by cyclization to afford pyrido[2',3':3,4]pyrazolo[5,1- c ]triazine derivative. Diazocoupling of the same dimethylpyrazolo[3,4- b ]pyridinediazonium chloride with unsymmetrical β-diketone, e. g. , benzoylacetone was also studied to afford the corresponding hydrazono derivative, which undergoes in situ cyclization to furnish the pyrido[2',3':3,4]pyrazolo[5,1- c ]triazine derivative. Also published in Chemistry of Heterocyclic Compounds , 2012, 48 (7), pp 1071-1077 http://link.springer.com/article/10.1007/s10593-012-1101-4