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