Palladium-Catalyzed Asymmetric B–H Arylation of <i>o</i> -Carboranes Assisted by a Chiral Transient Directing Group

Chiral-at-cage o-carboranes represent a class of three-dimensional boron-cluster-based chiral molecules. Herein, we report a Pd-catalyzed regio- and enantioselective B(4)–H arylation of o-carboranyl benzaldehydes enabled by a chiral transient directing group (cTDG) strategy using l-threonine. The reaction proceeds via reversible imine formation and enantioselective B–H arylation, affording chiral-at-cage products in up to 87% yield and 98% ee. Chiroptical characterizations confirm the potential of the products in optoelectronic materials. This work provides a practical approach to asymmetric B–H functionalization using in-situ-formed cTDGs.