N-Aminopyrazoles were oxidized by electrolysis in CH3CN to give 1, 2, 3-triazines and pyrazoles. The ratio of triazine formation increased when pyridine or H2O was added to the solvent. Reaction mechanisms were investigated by the application of electrochemical methods.
Vicarious nucleophilic substitution using chloromethyl phenyl sulfone was applied to pyridinium and 1, 2, 3-triazinium dicyanomethylides to afford corresponding 4-substituted pyiridinium and 5-substituted triazinium dicyanomethylides, respectively. They were readily transformed to 4-phenylsulfonylmethylpyridines and 5-phenylsulfonylmethyltriazines by radical reaction.
Monocyclic 1, 2, 3-triazines were reacted with ketene silyl acetal or silyl enol ether in the presence of 1-chloroethyl chloroformate to give 5-substituted 2-(1-chloroethoxycarbonyl)-2, 5-dihydrotriazines. These dihydro-adducts were readily oxidized and hydrolyzed with ceric ammonium nitrate in CH3CN/H2O to afford 5-substituted triazines.
Monocyclic 1,2,3-triazines have been allowed to react with silyl enol ether or ketene silyl acetal in the presence of 1-chloroethyl chloroformate to give 2-(1-chloroethoxycarbonyl)-5-substituted-2,5-dihydrotriazines in good yields. These dihydro adducts are oxidized by ceric ammonium nitrate in CH3CN–H2O to afford 5-substituted 1,2,3-triazines.
N-Oxidation of substituted 1, 2, 3-triazines afforded the 1- and/or 2-oxides. The molecular structure of 4, 5, 6-triphenyl-1, 2, 3-triazine 2-oxide was studied crystallographically.