Organoboron compounds
have important synthetic value and can be
applied in numerous transformations. The development of practical
and convenient ways to synthesize boronate esters has thus attracted
significant interest. Photoinduced borylations originated from stoichiometric
reactions of alkanes and arenes with well-defined metal–boryl
complexes. Now, photoredox-initiated borylations, catalyzed by either
transition metal or organic photocatalysts, and photochemical borylations
with high efficiency have become a burgeoning area of research. In
this Focus Review, we summarize research on photoinduced borylations,
especially emphasizing recent developments and trends. This includes
the photoinduced borylation of arenes, alkanes, aryl/alkyl halides,
activated carboxylic acids, amines, alcohols, and so on based on transition
metal catalysis, metal-free organocatalysis, and direct photochemical
activation. We focus on reaction mechanisms involving single-electron
transfer, triplet-energy transfer, and other radical processes.