4-Aryl-3-(methanesulfonyl)pyrazolo[5,1-c][1,2,4]triazines and their transformations

Coupling of 3-alkyl-4-aryl-1H-pyrazole-5-diazonium chlorides with methylene-active methyl phenacyl sulfones afforded new pyrazolo[5,1-c][1,2,4]triazine derivatives via cyclization of the corresponding intermediate 1-aryl-2-(hetarylhydrazinylidene)-2-(methanesulfonyl)ethanones. The reactivity of the methanesulfonyl group on C-3 of pyrazolo[5,1-c][1,2,4]triazines toward some nucleophiles was studied.