Herein we provide a bismuth-catalyzed reduction of nitroarenes to anilines using a simple and air-stable bismuth pre-catalyst. The reaction uses up to 5 mol% of Bi catalyst and PhSiH3 as the terminal reductant under mild conditions. The Bi pre-catalyst is an air-stable Bi(III), which is converted in the catalytically active species in situ by the PhSiH3. The mild reducing conditions permit the presence of aromatic halides. In analogy to the previous processes in bismuth catalysis, the reaction is speculated to proceed through a low-valent Bi(I)/Bi(III) redox cycle.
Liu et al. (Fri,) studied this question.