Recent advances in N-formylation of amines and nitroarenes using efficient (nano)catalysts in eco-friendly media
N-Formylation of amines or nitroarenes using catalysts is a prominent, chemoselective and efficient reaction for the fabrication of formyl amides. Formamides are one of the most valuable intermediates in pharmacological syntheses or important building blocks in synthetic and industrial organic chemistry, and have found widespread usage as pharmaceutically valuable intermediates and promising reagents in organic transformations. Formylation reactions catalyzed by unsupported or material-supported nanostructure catalysts are gaining significance; the conversion of all types of amines to formamides has been accomplished using reagents and an assortment of nanocatalysts, transition metal catalysts, organic catalysts and acidic catalysts. Amongst these, the most useful catalysts are often metal/metal oxide-based catalysts which are versatile and efficient. Heterogeneous nanocatalysts have found a unique niche for various N-formylation reactions owing to their thermal stability, reusability, large specific surface area, and high catalytic performance; nanotechnological innovations have enabled the emergence of techniques for fabricating these specific (nano)catalysts. In this overview, recent developments in the preparation, characterization, and catalytic application of various catalysts towards the N-formylation of amines or nitroarenes are presented and these are conducted in eco-friendly and green media including water, polyethylene glycol, and ionic liquids, as well as under solvent-free conditions.