N-Aryl-BIP Ligand-Enabled Iron-Catalyzed Asymmetric Synthesis of β-Amino Free Alcohols from Alkenes.

Herein, we report an iron-catalyzed enantioselective intermolecular NH2-aminoesterification of alkenes employing O-carbonyl hydroxylammonium triflates as bifunctional reagents, enabled by newly developed N-Aryl-BIP ligands. The resulting β-amino esters are susceptible to intramolecular transacylation and hydrolysis, effectively providing an overall asymmetric aminohydroxylation (AA) of alkenes. This transformation accommodates both vinyl (hetero)arenes and 1,1-disubstituted alkenes, delivering a diverse array of β-amino free alcohols in good yields and with high enantioselectivity. Mechanistic studies reveal a stepwise pathway involving electrophilic addition of the amino group to the alkene, followed by rapid C-O bond formation. Crossover and linear relationship experiments support a monomeric iron species bearing both the amino and carboxylate groups as the key reactive intermediate, which is interpreted as an iron(III)-supported amino radical (•NH2) species. DFT calculations indicate it undergoes a synchronous radical addition to the alkene coupled with ligand-to-metal single electron transfer, directly forming a benzylic carbocation. Subsequent C-O bond formation features a low kinetic barrier, which also represents the enantiodetermining step.