Regioselective oxidation of 3-monosubstituted juglone derivatives

Derivatives of 3-substituted juglones with either electron-withdrawing or -donating substituents are regioselectively oxidized to o- or p-naphthoquinones using salcomine/air or [bis(trifluoroacetoxy)iodo]benzene, respectively. The structure of the oxidation products was confirmed by chemical transformations. A correlation between chemical shift of the single quinoid proton and the quinone structure was established.