Chemoselective Reduction of Nitroarenes to Anilines Using a Nickel Foam

The reduction of nitroarenes to anilines is achieved using a nickel foam in acidic ethanol at room temperature. A defining feature of this protocol is its exceptional chemoselectivity, enabling the selective reduction of nitro groups in the presence of aryl halides, nitriles, alkenes, alkynes, and carbonyl derivatives. The selectivity of this method makes it especially powerful for preparing highly functionalized aromatic amines, indispensable motifs in the construction of complex targets, as exemplified by the synthesis of several important drugs and natural products. Structural and surface chemical analyses of the Ni foam before and after in situ activation, using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), reveal its gradual dissolution and the formation of square-shaped pits. The metallic nickel surface formed during activation is required for the reduction.