N-oxyphthalimides are stable and easily accessible compounds that can produce oxygen radicals upon 1-electron reduction. We present a systematic study of electrochemical properties of N-oxyphthalimide derivatives (PI-ORs) in DMF by cyclic voltammetry. In all cases, electron transfer to the substrate leads to decomposition of the intermediate radical anion via the N-O bond cleavage. In the case of benzyloxyphthalimide or its derivatives containing electrondonating substituents, reductive electron transfer induces the chain decomposition of the substrate to phthalimide (PI) radical-anion and the corresponding carbonyl compound. The PI radical-anion product is a powerful reductant that can transfer an electron to the reactant PI-OR, thus establishing a catalytic cycle for reductive N-O scission. This self-catalytic process is reflected in a considerable decrease in the reduction current for the substrate (<1e -/molecule). By contrast, reductive fragmentations of benzyl derivatives containing electronwithdrawing substituents in the aromatic ring or at the benzylic position, as well as tosyl and alkyl derivatives, occur via a 1-electron mechanism. A sequence of N-O and C-C scissions was engineered to support the intermediacy of O-centered radicals in these processes.

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Using 1,2-Acenaphthenedione as an example, cyclic voltammetry, chronoamperometry, coulometry, electrolysis and digital simulation were used to show that electroreduction of carbonyl compounds in the presence of nitromethane in 0.1 M Bu4NClO4/DMF proceeds via the ECE mechanism gives rise nitromethane anion initiating cyclic nitroaldol (Henry) process leading to β-nitroalcohols.

The electroreduction (ER) of benzo[a]phenazine-7,12-dioxide (1) and 2-ethoxycarbonyl-3methyl-quinoxaline-1,4-dioxide (2) in DMF on a glassy carbon electrode is studied by the methods of cyclic voltammetry, chronoamperometry, and electrolysis at controlled potential. In aprotic medium, these compounds are reduced to form relatively stable complexes as observed in both cyclic voltammetry curves and UV spectra. The deoxygenation of the derivatives of phenazine and quinoxaline N,N′-dioxides proceeds as a result of decomposition of the radical formed either at the ER of complexes of these compounds with СН 3 СООН or as a result of protonation of radical anions. For compound 2, the competition between the reactions of decomposition and ER of this radical is observed.