Green Approach for the Domino Reduction/Reductive Amination of Nitroarenes and Chemoselective Reduction of Aldehydes Using Fe/aq. Citric Acid/Montmorillonite K10

We have developed a new and mild method for the direct one-pot reduction/reductive amination of nitroarenes with arylaldehydes using Fe/aq citric acid/montmorillonite K10 catalytic system under ambient conditions. This catalyst has excellent functional group compatibility and the reaction provides rapid access to a diverse range of secondary amines. Under the conditions, aromatic aldehydes are selectively reduced to benzyl alcohols in the presence of ketones. A concise and efficient approach to the synthesis of diverse range of 1,2-disubstituted benzimidazoles has also been accomplished for the first time from 1,2-dinitrobenzene and aromatic aldehydes using the above catalytic system. The method involves the domino nitro reduction/cyclization/reduction cascade.