Epoxidation of unfunctionalized olefins by Mn(salen) catalyst using organic peracids as oxygen source: A theoretical study
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, GA 30322
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Edited by Barry M. Trost, Stanford University, Stanford, CA, and approved February 26, 2004 (received for review October 31, 2003)
Abstract
The mechanism and origin of asymmetric induction in the MnIII(salen)-catalyzed epoxidation by peracetic acid have been elucidated by the density functional [Becke three-parameter hybrid functional combined with Lee–Yang–Parr correlation functional (B3LYP)] method in two different regimes: with and without an axial ligand. The acylperoxo complexes of MnII,III,IV in cisON cisNO and trans geometrical configurations cannot compete with the catalyst-free Prilezhaev epoxidation. Instead, oxo species perform epoxidation following the O—O bond cleavage in the acylperoxo complexes. The epoxidation may proceed in a concerted and/or radical-mediated stepwise manner. The actual mechanism of the epoxidation depends on the electronic and oxidation state of the oxo species and the nature of the axial ligand. The olefin can approach the reactive MnO fragment of both cis and trans-l-isomers of the plain oxo species along multiple distinct directions: native approaches. The native approaches are used to rationalize the inversion of the absolute configuration of the product epoxide due to the axial ligand.
Footnotes
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↵ * To whom correspondence may be addressed. E-mail: dmusaev{at}emory.edu or morokuma{at}emory.edu.
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This paper was submitted directly (Track II) to the PNAS office.
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Abbreviations: DFT, density functional theory; B3LYP, Becke three-parameter hybrid functional combined with Lee–Yang–Parr correlation functional.
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↵ ‡ The table of Cartesian coordinates for all transition-state structures is available on request.
- Copyright © 2004, The National Academy of Sciences
