Electrochemical reduction of 1-aryl-4-nitroazoles

Electrochemical reduction of the nitro group in 1-aryl-4-nitroazoles occurs in slightly acidic medium as atypical four-electron process leading to hyd roxylamine group formation. The forming 1-aryl-4-hydroxylaminoazoles underg o further reactions. Stability of the hydroxylamines depends on the heteror ing (imidazole or pyrazole) and on C-substituents. More stable derivatives condense with the nitroso intermediates to yield azoxycompounds. Less stabl e hydroxylamines undergo rearrangements, azole ring reduction and decomposi tion. Some products of these transformations, following the electrochemical reduction, were isolated and their structures were fully characterized by standard methods.