Gold Catalysis Opens Up a New Route for the Synthesis of Benzimidazoylquinoxaline Derivatives from Biomass-Derived Products (Glycerol)

Process intensification by using well‐defined solid catalysts able to perform one‐pot multistep reactions is one of the open fronts in heterogeneous catalysis. This is even more relevant if new, more efficient synthesis routes are open. Herein, a gold catalyst was used to synthesize benzimidazoylquinoxalines compounds by two efficient and selective novel methods in a multistep one‐pot methodology. The first method involved the synthesis of benzimidazoylquinoxaline compounds with the same substituents in both heterocycles through oxidation–cyclization of glycerol with o‐phenylenediamine derivatives, whereas the second one allowed the synthesis of benzimidazoylquinoxalines compounds with different substituents in each aromatic ring through coupling of o‐phenylenediamine derivatives with glyceraldehyde in a first stage to produce the benzimidazol compound as an intermediate, followed by an oxidation–cyclization with another o‐phenylenediamine compound in a second stage. Both stages were performed by using gold nanoparticles supported on nanoparticulated ceria (Au/CeO2) as the catalyst and air as the oxidant, in absence of any homogeneous reagent. A reaction mechanism has been proposed. A smooth route: Benzimidazoylquinoxaline derivatives can be obtained in good yields through one‐pot oxidative coupling of glycerol or glyceraldehydes with 1,2‐phenylenediamines in a two‐step reaction, using Au/CeO2 as the catalyst, base‐free conditions, mild temperature, and air as the oxidant.