Cobalt Phosphide Catalyzed One-Pot Reductive N-Formylation of Nitroarenes: Structure-Activity Relationship.

The development of sustainable and efficient methodologies for the synthesis of formamides is of great significance due to their widespread use as intermediates in pharmaceuticals, agrochemicals, and fine chemicals. Herein, a cobalt phosphide (CoxP) has been developed via a facile annealing method and further employed for one-pot reductive N-formylation of nitroarenes to form N-phenylformamides using formic acid as a biorenewable hydrogen source formed via a dehydrogenation pathway and formylation source. In addition, a catalyst-free protocol was also developed for the direct N-formylation of aromatic amines to their corresponding N-phenylformamides. A broad range of nitroarenes and aromatic amines with varying substituents were successfully transformed into corresponding formamides. Furthermore, the structure-activity relationship was also discussed to correlate the properties of the catalyst with its performance toward the reductive N-formylation reaction. Green metrics parameters were evaluated to analyze the environmental impact and sustainability of the developed reaction protocol. An optimum value of renewable percentage for the developed reaction protocols suggests that the majority of the materials used in the reaction process were derived from renewable sources. Overall, this work provides an eco-friendly route to form N-phenyl formamides, showcasing the potential of CoxP in advancing non-noble metal-based heterogeneous catalysis for organic transformation reactions.