Boron Triiodide-Mediated Reduction of Nitroarenes Using Borohydride Reagents

The reduction of nitroarenes using KBH₄ and I₂ is described. BI₃ is generated in situ and was shown to be the active reductant. Conditions were optimized for BI₃ generation and then applied to a wide range of nitroarenes, including traditionally challenging substrates. The method constitutes a practical reduction option which produces low-toxicity boric acid and potassium iodide upon workup.