Asymmetric Epoxidation of Enones Promoted by Dinuclear Magnesium Catalyst
作者:Joanna A. Jaszczewska‐Adamczak、Jacek Mlynarski
DOI:10.1002/adsc.202100482
日期:2021.9.7
still a challenging task. In this perspective, we present the application of chiral dinuclear magnesium complexes for asymmetricepoxidation of a broad range of electron-deficient enones. We demonstrate that the in situ generated magnesium-ProPhenol complex affords enantioenriched oxiranes in high yields and with excellent enantioselectivities (up to 99% ee). Our extensive study verifies the literature
Convenient Preparation of Chiralα,β-Epoxy Ketonesvia Claisen–Schmidt Condensation-Epoxidation Sequence
作者:Yongcan Wang、Jinxing Ye、Xinmiao Liang
DOI:10.1002/adsc.200600592
日期:2007.5.7
A novel Clasisen–Schmidt condensation-epoxidationsequence of aldehydes and ketones was developed to produce a series of chiral α,β-epoxy ketones under asymmetric phase-transfer catalytic conditions. The organocatalytic method reported here can afford chiral α,β-epoxy ketones under mild conditions with moderate to good yields and up to 96 % ee.
Asymmetric epoxidation of (E)-chalcone with alkaline hydrogenperoxide by novel chiral phase-transfer catalysts (chiral PTCs) with quaternary ammonium salts of azacrown ether proceeded in high yield and good enantioselectivity. Remarkably, this reaction depended on the length of the carbon chain on the nitrogen atom with the chiral PTCs and on the bulk of the base.
Enantioselective Epoxidation of Electron-Deficient Alkenes Catalyzed by Manganese Complexes with Chiral N<sub>4</sub>
Ligands Derived from Rigid Chiral Diamines
作者:Xiangning Chen、Bao Gao、Yijin Su、Hanmin Huang
DOI:10.1002/adsc.201700541
日期:2017.8.7
series of tetradentate sp2N/sp3N hybrid chiral N4 ligands derived from rigid chiral diamines were synthesized, which enabled the first manganese-catalyzed enantioselective epoxidation of electron-deficientalkenes with hydrogenperoxide (H2O2) as an oxidant. The reaction furnishes enantiomerically pure epoxy amides, epoxy ketones as well as epoxy esters in good yields and excellent enantioselectivities
合成了一系列衍生自刚性手性二胺的四齿sp 2 N / sp 3 N杂合手性N 4配体,这使锰能够以过氧化氢(H 2 O 2)为氧化剂,首次对缺电子烯烃进行对映选择性环氧化。。该反应以较低的催化剂负载量提供了对映体纯的环氧酰胺,环氧酮以及环氧酯,具有良好的收率和优异的对映选择性(最高99.9%ee)。对结构-活性关系的初步研究表明,保持sp 3的相对较低的供电子能力N和N 2配体的sp 2 N的相对较高的供电子能力有利于获得更高的活性和选择性,从而为我们理解H 2 O 2的环氧化提供了新的视角。
Chiral octahedral complexes of Co(<scp>iii</scp>) as catalysts for asymmetric epoxidation of chalcones under phase transfer conditions
作者:Vladimir A. Larionov、Elina P. Markelova、Alexander F. Smol'yakov、Tat'yana F. Savel'yeva、Victor I. Maleev、Yuri N. Belokon
DOI:10.1039/c5ra11760g
日期:——
Stereochemically inert and positively charged chiralcomplexes of Co(III) were shown to catalyze the asymmetric epoxidation of chalcones with H2O2 under phase transfer conditions. The reaction products had enantiomeric purities of up to 55%. It was also shown that complex 1a I− catalyzed the coupling reaction of a resulting epoxide with CO2 (conversion 72%).
在相转移条件下,Co(III)的立体化学惰性和带正电荷的手性配合物可催化查耳酮与H 2 O 2的不对称环氧化。反应产物的对映体纯度高达55%。它也表明,复杂1A我-催化的与CO所得环氧化物的偶联反应2(转化72%)。