Proton-Promoted and Anion-Enhanced Epoxidation of Olefins by Hydrogen Peroxide in the Presence of Nonheme Manganese Catalysts

Chengxia Miao, Bin Wang, Yong Wang, Chungu Xia, Yong Min Lee, Wonwoo Nam, Wei Sun

Research output: Contribution to journalArticlepeer-review

112 Scopus citations


We report a remarkable Brønsted acid effect in the epoxidation of olefins by nonheme manganese catalysts and aqueous hydrogen peroxide. More specifically, a mononuclear nonheme manganese complex bearing a tetradentate N4 ligand, MnII(Dbp-MCP)(OTf)2 (Dbp-MCP = (1R,2R)-N,N′-dimethyl-N,N′-bis((R)-(3,5-di-tert-butyl-phenyl)-2-pyridinylmethyl)cyclohexane-1,2-diamine; OTf- = CF3SO3 -), is a highly efficient catalyst in the epoxidation of olefins by aqueous H2O2 in the presence of H2SO4 (1-3 mol %). The yields of epoxide products as well as the chemo- and enantioselectivities increase dramatically in the presence of H2SO4; no formation of epoxides is observed in the absence of H2SO4. In addition, the product yields and enantioselectivities are dependent significantly on the manganese catalysts and Brønsted acids. The catalytic epoxidation of olefins by other oxidants, such as peracids, alkyl hydroperoxides, and iodosylbenzene, is also affected by the presence of H2SO4; product yields and enantioselectivities are high and similar irrespective of the oxidants in the presence of H2SO4, suggesting that a common epoxidizing intermediate is generated in the reactions of [MnII(Dbp-MCP)]2+ and the oxidants. Mechanistic studies, performed with 18O-labeled water (H2 18O) and cumyl hydroperoxide, reveal that a high-valent manganese-oxo species is formed as an epoxidizing intermediate via O-O bond heterolysis of Mn-OOH(R) species. The role of H2SO4 is proposed to facilitate the formation of a high-valent Mn-oxo species and to increase the oxidizing power and enantioselectivity of the Mn-oxo oxidant in olefin epoxidation reactions. Density functional theory (DFT) calculations support experimental results such as the formation of a Mn(V)-oxo species as an epoxidizing intermediate.

Original languageEnglish
Pages (from-to)936-943
Number of pages8
JournalJournal of the American Chemical Society
Issue number3
StatePublished - 27 Jan 2016

Bibliographical note

Funding Information:
We acknowledge financial support of this work from the National Natural Science Foundation of China (21473226 and 21133011 to W.S. and Grant No. 21173211 to Y.W) and the NRF of Korea through CRI (NRF-2012R1A3A2048842 to W.N.) and GRL (NRF-2010-00353 to W.N.).

Publisher Copyright:
© 2015 American Chemical Society.


Dive into the research topics of 'Proton-Promoted and Anion-Enhanced Epoxidation of Olefins by Hydrogen Peroxide in the Presence of Nonheme Manganese Catalysts'. Together they form a unique fingerprint.

Cite this