Asymmetric Iron-Catalyzed Multicomponent Radical Dicarbofunctionalization of Vinyl Organoboron Compounds

Developing asymmetric methodologies using readily available building blocks remains a central challenge in chemical synthesis. Despite advances in asymmetric multicomponent radical cross-couplings, methods that use earth-abundant iron catalysts and nonphosphine ligand platforms remain rare and poorly understood. We report an iron-catalyzed asymmetric radical dicarbofunctionalization of vinyl boronate esters using inexpensive iron salts with chiral bisoxazoline or amide ligands, affording diverse, enantioenriched alkyl boron compounds with high levels of stereoselectivity (up to 99:1 e.r.). Mechanistic investigations combining 80 K 57Fe Mössbauer spectroscopy, single-crystal X-ray analysis, and quantum mechanical calculations reveal a catalytic cycle involving chiral bis- and mono-aryl iron (II) (BOX) species responsible for radical capture and C−C bond formation. This work establishes a distinct mechanistic paradigm for asymmetric radical cross-coupling and provides general design principles for enantioselective catalysis with earth-abundant metals.