BX₃-mediated borylation for the synthesis of organoboron compounds

Organoboron compounds now known as versatile building blocks are broadly used in a variety of transformations in the fields of organic synthesis, drug synthesis, and materials science. The practical and convenient synthesis methodology of organoboron compounds has been well developed. Generally, organoboron compounds are prepared through transmetalation reactions using organolithium or organomagnesium reagents, hydroboration of C–C unsaturated bonds, borylation of CX double bonds, or borylation of C–H/C–X bonds. Among these methods, bis(pinacolato)diboron (B₂pin₂) and pinacol borane (HBpin) are used extensively. Recently, borylation mediated by BX₃ for the efficient synthesis of organoborons has been well developed. In this review, we summarize the research on borylation driven by BX₃ in the fields of organic synthesis and drug synthesis, including (1) borylative difunctionalization of C–C unsaturated bonds and (2) C–H bond borylation. The strategies of borylation processes as well as the scopes, limits, and mechanisms of these approaches are addressed.