Visible Light-Induced Borylation of C–O, C–N, and C–X Bonds

• Published in: Journal of the American Chemical Society Vol. 142; no. 3; pp. 1603 - 1613
• Main Authors: Jin, Shengfei, Dang, Hang. T, Haug, Graham C, He, Ru, Nguyen, Viet D, Nguyen, Vu T, Arman, Hadi D, Schanze, Kirk S, Larionov, Oleg V
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 22.01.2020; Amer Chemical Soc
• Subjects: Boronic Acids - chemistry; Carbon - chemistry; Catalysis; Chemistry; Chemistry, Multidisciplinary; Light; Nitrogen - chemistry; Oxygen - chemistry; Physical Sciences; Science & Technology; HALIDES; CHLORIDES; ARYL; CATALYZED BORYLATION; ACIDS; ESTERS
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.9b12519

Boronic acids are centrally important functional motifs and synthetic precursors. Visible light-induced borylation may provide access to structurally diverse boronates, but a broadly efficient photocatalytic borylation method that can effect borylation of a wide range of substrates, including strong C–O bonds, remains elusive. Herein, we report a general, metal-free visible light-induced photocatalytic borylation platform that enables borylation of electron-rich derivatives of phenols and anilines, chloroarenes, as well as other haloarenes. The reaction exhibits excellent functional group tolerance, as demonstrated by the borylation of a range of structurally complex substrates. Remarkably, the reaction is catalyzed by phenothiazine, a simple organic photocatalyst with MW < 200 that mediates the previously unachievable visible light-induced single electron reduction of phenol derivatives with reduction potentials as negative as approximately – 3 V versus SCE by a proton-coupled electron transfer mechanism. Mechanistic studies point to the crucial role of the photocatalyst–base interaction.