Synthesis of New Regioisomers of 5-Nitro-1,4-Naphthoquinone, Evaluation of Antioxidant and Catalase Inhibition Activities

Abstract

The studies on nitronaphthoquinone derivatives are rare in the literature, and the nitro group associated with the aromatic ring in the quinone system is known to increase the biological activity of naphthoquinone due to its electron-withdrawing properties. In the course of quinone derivatives, the new N(H)-substituted-5-nitro-1,4-naphthoquinones (NQ) as regioisomers were synthesized by reactions of 2,3-dichloro-5-nitro-1,4-naphthoquinone with some heterocyclic ring substituted nucleophiles such as anilines, piperazines, or morpholines, according to a Michael 1,4-addition mechanism. Five NQ regioisomer couples having different functional group (2-chloro-isomers 3, 5, 7, 9 and 13; 3-chloro-isomers 2, 4, 6, 8 and 12) are reported here. All new synthesized compounds were characterized by spectroscopic methods and two-dimensional NMR techniques H-1-H-1 correlated spectroscopy (COSY).