Light-Promoted Low-Valent-Tungsten-Catalyzed Ambient Temperature Amination of Boronic Acids with Nitroaromatics

Triggering C-N bond formation with nitroaromatics and boronic acids at mild conditions is highly desirable, since most prior works were carried out under harsh conditions and sometimes suffered from poor chemo- or regioselectivity. Herein, a low-valent-tungsten-catalyzed reaction that enables the ambient temperature amination of boronic acids with nitroaromatics is disclosed. With readily available W(CO)6 as a precatalyst under external-photosensitizer-free conditions, nitroaromatics smoothly undergo C-N coupling reactions with their boronic acid partners, delivering structurally diverse secondary amines in good yields (>50 examples, yields up to 96%). This methodology is both scalable and highly chemoselective and engages both aliphatic and aromatic boronic acid partners. The catalysis is initiated by the deoxygenation of nitroaromatics by a trans-[W(CO)4(PPh3)2] (trans-W, PPh3 = triphenylphosphine) complex, which forms in situ via ligand replacement.