Reductive Buchwald-Hartwig Amination of Nitroarenes with Aryl (pseudo)Halides

De novo catalytic syntheses of diarylamines from a palladium-catalyzed reductive Buchwald-Hartwig amination of nitroarenes with aryl (pseudo)halides is described. The exquisite use of upstream nitroarenes as arylamine surrogates, the judicious selection of bis(pinacolato)diboron (B(2)pin(2)) as a stoichiometric reducing agent, and wide substrate scope including (hetero)aryl halides (Cl, Br and I) and aryl triflates, constitute the striking features of the current protocol. Moreover, application of this technique to the syntheses of advanced intermediates and active pharmaceutical ingredients also proved successful, thus providing an alternative step-economical approach to the syntheses of diarylamine-incorporated molecules. Preliminary mechanistic investigation demonstrates that an amine and a nitrosoarene intermediates might be involved in this reductive event.