Green and eco-compatible iron nanocatalysed synthesis of benzimidazole: A review

Benzimidazole moiety occupies a prominent position among all heterocyclic compounds along with N-containing heterocycles due to its widespread use in the medical field. In addition to medical uses, this bioactive heterocyclic moiety is also found in many important biological compounds, which are present in nature. Because of these diverse characteristics, chemists drew attention to the synthesis of benzimidazoles. As a result, benzimidazoles derivatives started being synthesized with the help of various chemical methods but these conventional processes were plagued with several drawbacks such as low atom economy, severe reaction conditions, long reaction times, by-product formation, non-recyclable catalysts, unsatisfactory product yield, hazardous solvents etc. So to overcome this problem, chemists are focusing their efforts on inventing synthetic approaches that are primarily based on the principles of green chemistry. We have focused in this review paper to systematically demonstrate several greener and more efficient approaches for the preparation of benzimidazoles from o-phenylenediamine by using Iron-based nanocatalysts. Finally, this review will also help the researchers to develop more efficient and simpler routes for synthesizing benzimidazoles and their derivatives.