Recyclization-Isomerization in the Reduction of 1-(2-Nitro(het)aryl)benzimidazoles

摘要

abstract_textpThe regularities of reductive recyclization-isomerization of 1-(2-nitro(het)aryl)-substituted benzimidazoles discovered by the authors have been studied. The structure of the intermediate has been identified and the isomerization process has been found to be reversible. The shift of equilibrium between the resulting isomers is affected by the reaction temperature and time, the amount of hydrogen chloride in the reaction mixture and the substrate structure. According to the suggested reaction mechanism, the amino group formed upon reduction reacts with the electron-deficient alpha-carbon atom in an imidazole by an Ad(N) reaction. Based on these studies, a method for the functionalization of benzimidazoles has been developed. This young methodology has been used to synthesize hitherto unknown benzimidazole derivatives that are difficult to obtain by other methods./p/abstract_text