Asymmetric Homogeneous Oxidation Reactions Catalyzed by First-Row Transition Metal Complexes

Asymmetric homogeneous oxidation reactions catalyzed by first-row transition metal complexes have been summarized, focusing on the performance of the chiral catalyst and its relation with the key factors (structure of the chiral ligands, type of metal, solvent, temperature, and oxidant) in the catalytic systems. A variety of oxidants, including hydrogen peroxide (H₂O₂), molecular oxygen (O₂), sodium hypochlorite (NaOCl), tert-butyl hydroperoxide (TBHP), and iodosylbenzene (PhIO), have been employed for the oxidation reactions using different chiral transition metal complexes. This review is mainly focused on the reports of various asymmetric metal complexes as homogeneous catalysts derived from first-row transition metals and chiral ligands for a range of oxidation reactions, such as epoxidation of olefins and α,β-unsaturated carbonyl compounds, sulfoxidation, hydroxylation, dihydroxylation, and oxidation of spirocyclic compounds. Several chiral ligands and their metal complexes (including metals titanium, chromium, manganese, iron, cobalt, and vanadium) are utilized in asymmetric oxidation reactions, whereas asymmetric manganese complexes have been extensively used for epoxidation, hydroxylation, and oxidative kinetic resolution. This review provides a clear and broad perception for better recognizing the homogeneous asymmetric catalysts used in oxidation reactions.