Abstract
Arylhydrazonomalononitriles 1a,b react with phenylhydrazine to yield amidrazones 2a,b that cyclize to give 2-aryl-5-phenylhydrazono-2,5-dihydro-[1,2,4]-triazine-6-carbonitriles 5a,b upon reaction with dimethylformamide dimethylacetal (DMFDMA). Refluxing 5a,b in glacial acetic acid resulted in the formation of the pyrazolo-1,2,4-triazines 6a,b. Compounds 6a,b were also formed upon treatment of 3-amino-4-phenylhydrazono-1-phenyl-2-pyrazolin-5-ones 7a,b with DMFDMA. Reacting these triazinyl arylhydrazononitriles 5a,b with hydroxylamine hydrochloride in ethanolic sodium acetate afforded amidrazones 8a,b that are readily cyclized in refluxing dimethylformamide into [1,2,4]triazino[1,2,3]triazines 10a,b.
Highlights
Arylhydrazonomalononitriles 1 are synthetically useful reagents that have been utilized in the past as precursors to 4-arylazo-3,5-pyrazolediamines as well as [1,2,3]triazoleamines and pyrazolo[1,5a]pyrimidines [1]
Molecules 2010, 15 that have been patented as a hair dyes, similar treatment with hydroxylamine hydrochloride has resulted, in our hands, in isolation of amidoximes that were utilized as precursors to other heterocycles
We report here the results of our reinvestigation of the behavior of compounds 1a,b toward phenylhydrazine. 1,2,3-Triazine derivatives are an important class of heterocyclic compounds useful in organic synthesis and as pharmaceuticals
Summary
Arylhydrazonomalononitriles 1 are synthetically useful reagents that have been utilized in the past as precursors to 4-arylazo-3,5-pyrazolediamines as well as [1,2,3]triazoleamines and pyrazolo[1,5a]pyrimidines [1]. The mixture was stirred at room temperature for 1 h and the solid product formed was collected by filtration, washed with water and recrystallized from ethanol.
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