Theoretical and experimental investigations of the enantioselective epoxidation of olefins catalyzed by manganese complexes

The enantioselective epoxidation of olefin by Mn-II(R,R-PMCP)(OTf)(2), H2O2 and H2SO4 was explored by DFT calculations and experiments. Theoretical results suggest that [Mn-V(O)(R,R-PMCP)(SO4)](+) species with a triplet ground spin state serves as the active species for the olefin epoxidation. It can be generated by the H2SO4 assisted O-O heterolysis of Mn-III(OOH) species. Mn-III-persulfate is also involved in this system, but it cannot promote the olefin epoxidation directly, preferring instead to transform into Mn-V(O). Actually, the asymmetric epoxidation reactions with H2O2/H2SO4 or Oxone provide similar enantioselectivity in the presence of manganese catalyst. These observations further support the transformation of Mn-III-persulfate to Mn-V(O) species. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.