A mild oxidation of deactivated naphthalenes and anthracenes to corresponding para-quinones by N-bromosuccinimide

A new method to synthesize 1,4-naphthoquinone and 9,10-anthraquinone from naphthalene and anthracene functionalized with either –CHO or –COOH groups, using N-bromosuccinimide (NBS) in aqueous N,N-dimethylformamide at 75–80 °C, has been developed. Further, –CN and –CONH2 functionalized naphthalenes and anthracenes can also be transformed into respective para-quinones in a one pot reaction, after successive acid hydrolysis and subsequent reaction with NBS. We believe that the present finding may serve as a valuable alternative to the classical approaches for the synthesis of polycyclic quinones from polyaromatic carbaldehydes through Dakin oxidation followed by further oxidation of the resulting hydroquinone by heavy metal oxides.