Ruthenium carbonyl-catalyzed deoxygenation by carbon monoxide of o-substituted nitrobenzenes. Synthesis of benzimidazoles

Article abstract of DOI:10.1016/0304-5102(92)85006-2

Ru₃(CO)₁₂ is a very efficient catalyst for the deoxygenation of 2-nitro-N-(phenylmethylene) benzeneamine derivatives to give the corresponding 2-substituted benzimidazoles, at 220°C and 50 bar of carbon monoxide. Main byproducts are the corresponding amines. The same benzimidazoles are also obtained starting from o-nitroaniline and the corresponding aldehyde. When N-(2-nitrophenyl)methylene benzencamine derivatives are used as substrates, the reaction changes dramatically and only traces of the corresponding heterocyclic compounds are obtained, although complete conversion of the starting nitro compounds is achieved.