Photo-Induced Thiolate Catalytic Activation of Inert Caryl-Hetero Bonds for Radical Borylation

Abstract

Cross-coupling reactions are essential tools in modern synthesis of drugs, natural products and materials. The recent developments in photocatalytic radical generation have improved and expanded the classic metal-catalyzed cross coupling reactions even further. However, for sp<sup>2</sup> cross coupling reactions aryl halides or related active leaving groups, such as triflates, are required. Substituted arenes bearing strong C-X bonds remain inert to current methods. We describe now a new thiolate photocatalysis for the activation of inert substituted arenes in ipso-borylation reactions. This catalytic system exhibits strong reducing power and allows the borylation of stable C<sub>aryl</sub>−F, C<sub>aryl</sub>−O, C<sub>aryl</sub>-N and C<sub>aryl</sub>−S bonds, which are considered as chemically stable at mild reaction conditions. Our method considerably widens the available substrate scope of aryl radical precursors and we anticipate that this report will inspire new chemistry based on inert chemical bond activation.