Chiral Bioinspired Non‐Heme Iron Complexes for Enantioselective Epoxidation of α,β‐Unsaturated Ketones

Chiral bioinspired iron complexes of N 4 ligands based on the ethylenediamine backbone display remarkable levels of enantioselectivity for the first time in the asymmetric epoxidation of α,β‐unsaturated ketones using hydrogen peroxide (up to 87% ee ) or peracetic acid as oxidant, respectively. Notablely, isotopic labeling with H 2 18 O strongly demonstrated that there is a reversible water binding step prior to generation of the significant intermediate. Besides, the complex [L 2 Fe(III) 2 (μ‐O)(μ‐CH 3 CO 2 )] 3+ usually derived from the decay of the LFe(IV)O species or thermodynamic sinks for a number of iron complexes was identified by HR‐MS. In addition, the possible mechanisms were proposed and LFe(V)O species may be the main active intermediate in the catalytic system.