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.