Rhodium(I)-Catalyzed Asymmetric Carbene Insertion into B–H Bonds: Highly Enantioselective Access to Functionalized Organoboranes

A unique rhodium­(I)-catalyzed asymmetric B–H insertion of α-diazo carbonyl compounds with easily available amine–borane adducts was achieved using a newly developed C1-symmetric chiral diene as ligand. This first Rh­(I)–carbene-directed B–H insertion example represents an attractive and promising approach for synthesis of highly enantio­enriched organoboron compounds, allowing for the efficient construction of α-boryl esters and ketones with excellent enantio­selectivities (up to 99% ee) under exceptionally mild conditions.