Song Heng, Shen Yang, Zhou Hu, Ding Danli, Yang Fu, Wang Yemei, Xu Chen, Cai Xingwei
School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003, P. R. China.
J Org Chem. 2022 Apr 15;87(8):5303-5314. doi: 10.1021/acs.joc.2c00138. Epub 2022 Apr 1.
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) 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 -[W(CO)(PPh)] (-, PPh = triphenylphosphine) complex, which forms via ligand replacement.
在温和条件下利用硝基芳烃和硼酸引发碳氮键形成是非常可取的，因为大多数先前的工作是在苛刻条件下进行的，有时还存在化学选择性或区域选择性差的问题。在此，公开了一种低价钨催化的反应，该反应能够使硼酸与硝基芳烃在环境温度下进行胺化反应。以易于获得的W(CO)作为预催化剂，在无外部光敏剂的条件下，硝基芳烃能与其硼酸伙伴顺利发生碳氮偶联反应，以良好的产率得到结构多样的仲胺（>50个实例，产率高达96%）。该方法具有可扩展性且化学选择性高，脂肪族和芳香族硼酸伙伴均可参与反应。催化反应由-[W(CO)(PPh)]（-，PPh = 三苯基膦）配合物使硝基芳烃脱氧引发，该配合物通过配体置换形成。
