Iodine-mediated construction of polyfunctionalized arylazopyrazoles from β-ketoesters or 2-arylpyrazol-3-ones and arylhydrazines.

This paper describes step-economic iodine-mediated construction of functionalized arylazopyrazoles in the presence of catalytic AgNO3 starting from simple β-ketoesters and two equivalents of arylhydrazines. This cascade reaction includes in situα-iodination of β-ketoesters, pyrazol-3-one formation, substitution with a nitrogen nucleophile, and oxidation/aromatization.