Substrate-directed C(sp3)–H borylation via transition metal catalysis: expanding the toolbox for C–H functionalization

Organoborons play a crucial role in organic synthesis, easing the construction of C–C and C–X bonds, which in turn sensitize C–H borylation reactions. In the context of inert C(sp³)–H borylation, significant efforts have been dedicated to achieve site- and chemoselectivity by involving directing groups via transition metal catalysis. This review highlights various types of directing groups that can enable intricate and distal C(sp³)–H borylation; heteroatoms such as P, N, B, Si, Br, O, and Cl, which are attached to the substrate, act as the directing group. In addition to homogeneous catalysis, the occurrence of heterogeneous catalysis was realized, and the considerable contribution to chiral C(sp³)–H borylation is discussed. Finally, this review summarizes the mechanistic aspects and late-stage modifications of complex molecules.