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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Epoxidation of unfunctionalized olefins by Mn(salen) catalyst using organic peracids as oxygen source: A theoretical study
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Epoxidation of unfunctionalized olefins by Mn(salen) catalyst using organic peracids as oxygen source: A theoretical study

机译：有机过酸作为氧源的Mn（salen）催化剂对未官能化烯烃的环氧化作用：理论研究

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摘要

The mechanism and origin of asymmetric induction in the Mn-III(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 Mn-II,Mn-III,Mn-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.
机译：通过密度泛函[Becke三参数混合泛函结合Lee-Yang-Parr相关泛函（B3LYP）]方法阐明了Mn-III（salen）催化过氧乙酸环氧化中的不对称诱导机理和起源。两种不同的方案：有和没有轴向配体。顺式cisNO和反式几何构型的Mn-II，Mn-III，Mn-IV的酰基过氧配合物不能与无催化剂的Prilezhaev环氧化反应竞争。取而代之的是，羰基过氧化物络合物中的O-O键断裂后，羰基化合物会进行环氧化。环氧化可以以协同和/或自由基介导的逐步方式进行。环氧化的实际机理取决于氧代物质的电子和氧化态以及轴向配体的性质。烯烃可以沿多个不同方向接近纯氧代物种的顺式和反式L-异构体的反应性MnO片段：天然方法。天然方法用于合理化由于轴向配体导致的产物环氧化物的绝对构型的反转。

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