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 alpha-diazo carbonyl compounds with easily available amine borane adducts was achieved using a newly developed C-1-symmetric chiral diene as ligand. This first Rh(I) carbene directed insertion example represents an attractive and promising approach for synthesis of highly enantioenriched organoboron compounds pounds, allowing for the efficient Construction Of alpha-boryl esters and ketones with excellent enantioselectivities (up to 99% ee) under exceptionally mild conditions.