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

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 reac-tion exhibits excellent functional group tolerance, as demon-strated by the borylation of a range of structurally complex substrates. Remarkably, the reaction is catalyzed by phenothi-azine, - a simple organic photocatalyst with MW<200 that me-diates the previously unachievable visible light-induced single electron reduction of phenol derivatives with reduction poten-tials as negative as ~ −3 V vs SCE by a proton-coupled electron transfer mechanism. Mechanisti...