The Electrochemical Reduction of Fluorenone Tosylhydrazone: Evidence Consistent with Formation of the Tosyl Nitrene Anion Radical

Article abstract of DOI:10.1021/jo00363a027

Fluorenone tosylhydrazone (Fl=NNHTs) undergoes one-electron reductive dehydrogenation in DMF-0.1 F (n-Bu)4NClO4 to give hydrogen and its conjugate base Fl=NN^-Ts as products.Fl=NN^-Ts is subsequently reduced at more negative potential to a dianion radical (Fl=NNTs dianion radical) that is stable on the cyclic voltammetric time scale.On the coulometric time scale or in the presence of added proton donors (pK_a < ca.29), Fl=NNTs dianion radical decomposes to give FlHNH2 and TsNH2 as the principal products.A pathway is proposed for the reaction of Fl=NNTs dianion radical which involves rate-determining proton abstraction by the nitrogen atom α to the fluorene moiety.Cyclic voltammetric and chronoamperometric data are presented which are consistent with the formation of the tosyl nitrene anion radical as a short-lived, unobserved intermediate.