Boron/Silicon in the Development of Chiral Ligands for Asymmetric Transition-Metal Catalysis

Chiral ligands are on the central stage of asymmetric catalysis, and classical chiral ligands typically rely on carbon stereocenters. Integrating metalloid elements like boron and silicon into chiral ligand frameworks offers a powerful alternative to classical carbon-based systems in asymmetric transition-metal catalysis. This review summarizes recent developments in boron-and silicon-modified chiral ligands, focusing on their distinct electronic and structural attributes. Boron acts effectively as an anionic backbone node or a direct donor site; representative borabox and N,B-bidentate ligands facilitate copper-catalyzed cyclopropanation and iridium-catalyzed C-H borylation. Meanwhile, silicon's reduced electronegativity and elongated bonds provide tailored steric shielding and electronic modulation, exemplified by spiro-silabiindane scaffolds in rhodium-catalyzed hydrogenation and palladium-catalyzed allylic substitution. However, persistent hurdles still remain, particularly the lability of B-M bonds, restricted boryl diversity, and the challenging construction of siliconstereogenic centers, and overcoming these synthetic bottlenecks will drive the rational design of highly effective, multifunctional metalloid-based chiral ligands for modern organic synthesis.