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Paper | Regular issue | Vol 53, No. 10, 2000, pp.2175-2181
Published online, 1st January, 1970
DOI: 10.3987/COM-00-8972
A New Synthesis of Pyrazolo[4,3-e][1,2,4]triazines via Acid Promoted Ring Closure of the Phenylhydrazones of 5-Acyl-1,2,4-triazines

Andrzej Rykowski,* Mariusz Mojzych, and Zbigniew Karczmarzyk

*Institute of Chemistry, University of Podlasie, 08-110 Siedlce, Poland


The reaction of various substituted phenylhydrazones of 5-acyl-1,2,4-triazines in the presence of 1.1 equivalent of HCl in boiling ethanol-dioxane mixture has been studied. In all reactions the formation of the corresponding pyrazolo[4,3-e][1,2,4]triazines (3a-r) takes place in good yield. The structures of 3a-r were unequivocally established by spectroscopic methods as well as by X-Ray analysis of selected 5-methyl-3-phenyl-7-(p-tolyl)pyrazolo[4,3-e][1,2,4]triazine (3a).