Sustainable synthesis of azobenzenes, quinolines and quinoxalines via oxidative dehydrogenative couplings catalysed by reusable transition metal oxide–Bi(iii) cooperative catalysts

Abstract

Oxidative dehydrogenative coupling (ODC) is a useful tool for the formation of new C–C, C–O and NN bonds in an atom-economic and sustainable manner. Although this strategy is versatile, it is much less introduced to prepare N-heterocycles. Herein, we report the oxidative dehydrogenative coupling of anilines and 2-aminoanilies with vicinal diols to selectively produce azobenzenes (34–95% yield), quinolines (65–100% yield) and quinoxalines (78–100% yield) utilizing an environmentally friendly synthesis strategy. The reactions were catalysed by cooperative bifunctional catalysts based on transition metal oxides/Bi(III) which allow solvent-, additive-, oxidant- and base-free cyclisations/couplings. In addition, the catalysts were proven to be highly robust and reusable.