A novel and convenient one-pot synthesis of 3-amino-2 H-1,2,4-triazoles from two molecules of isoselenocyanates and hydrazine hydrate via cyclodeselenisation was developed. Various 3-amino-2 H-1,2,4-triazoles were obtained in moderate to good yields (33–45%, based on isoselenocyanates). The selenium powder and aromatic amine side products during the reaction could be recycled for efficient preparation of isoselenocyanates, which improved the atom economy. A plausible mechanism was proposed for the formation of the target products.
One-pot synthesis of azide-substituted dihydropyrazoles in isopropanol was performed using chalcones, hydrazine hydrate, and acyl chloride at 0℃, and its subsequent Staudinger-aza-Wittig-dehydroaromatization reactions with methyldiphenylphosphine were also investigated for further application in the construction of pyrazolo[1,5-c]quinazolines.
Two efficient regioselective approaches for the one-pot synthesis of 3-arylpyridazino[4,3-c]quinolin-5(6H)-one derivatives are reported, by the three-component reaction of arylglyoxal monohydrates, quinoline-2,4-diol, and hydrazinium dihydrochloride or hydrazine hydrate in ethanol and pyridine. In ethanol, the reactions were catalyzed by 1,4-diazobicyclo[2,2,2]octane. The features of both procedures are high regioselectivity, mild reaction conditions, good to high yields, and operational simplicity.
One-pot synthesis of functionalized pyrazolo[3,4-c]pyrazoles by reaction of 2-cyano-N-methyl-acrylamide, aryl aldehyde, and hydrazine hydrate
