Preparation of substituted anilines from nitro compounds by using supported gold catalysts.

A protocol for the chemoselective hydrogenation of nitro compounds to the corresponding anilines by means of supported gold catalysts is described. Nitro groups on different compounds--containing double bonds, carbonyl, nitrile or amide groups--have been successfully hydrogenated on supported gold nanoparticles (Au/TiO2 and Au/Fe2O3), using a batch reactor under H2 pressure. Unlike other noble metals, gold shows high chemoselectivity towards reduction of the nitro group, at near-complete conversion of the substrate. The total time to carry out this protocol strongly depends on the reaction step, which is a function of the activity of the catalyst and the nature of the substrate.