The Cinchona Primary Amine-Catalyzed Asymmetric Epoxidation and Hydroperoxidation of α,β-Unsaturated Carbonyl Compounds with Hydrogen Peroxide
作者:Olga Lifchits、Manuel Mahlau、Corinna M. Reisinger、Anna Lee、Christophe Farès、Iakov Polyak、Gopinadhanpillai Gopakumar、Walter Thiel、Benjamin List
DOI:10.1021/ja402058v
日期:2013.5.1
Using cinchona alkaloid-derived primary amines as catalysts and aqueous hydrogenperoxide as the oxidant, we have developed highly enantioselective Weitz-Scheffer-type epoxidation and hydroperoxidation reactions of α,β-unsaturated carbonylcompounds (up to 99.5:0.5 er). In this article, we present our full studies on this family of reactions, employing acyclic enones, 5-15-membered cyclic enones, and
Iron Catalyzed Highly Enantioselective Epoxidation of Cyclic Aliphatic Enones with Aqueous H<sub>2</sub>O<sub>2</sub>
作者:Olaf Cussó、Marco Cianfanelli、Xavi Ribas、Robertus J. M. Klein Gebbink、Miquel Costas
DOI:10.1021/jacs.5b12681
日期:2016.3.2
An iron complex with a C1-symmetric tetradentate N-based ligand catalyzes the asymmetric epoxidation of cyclic enones and cyclohexene ketones with aqueous hydrogen peroxide, providing the corresponding epoxides in good to excellent yields and enantioselectivities (up to 99% yield, and 95% ee), under mild conditions and in short reaction times. Evidence is provided that reactions involve an electrophilic
具有 C1 对称四齿 N 基配体的铁配合物催化环烯酮和环己烯酮与过氧化氢水溶液的不对称环氧化反应,提供相应的环氧化物,产率和对映选择性都很好(高达 99% 和 95% ee ),条件温和,反应时间短。有证据表明反应涉及亲电氧化剂,并且该元素用于对包含两个烯烃位点的烯酮进行位点选择性环氧化。
Efficient Synthesis of Anastrephin via the Allylic Substitution for Quaternary Carbon Construction
Horner–Wadsworth–Emmons olefination, conversion to the allylic moiety, and epoxide ring opening with Et2AlCH2CO2 t-Bu. The allylic substitution of the picolinate with Me2CuMgBr·MgBr2 furnished a quaternary carbon center with 92% ds. Finally, the lactonization of the product, the tert-butyl ester of the seco acid, under acidic conditions, afforded (–)-anastrephin.
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
Synthesis of 2-Nickela(II)oxetanes from Nickel(0) and Epoxides: Structure, Reactivity, and a New Mechanism of Formation
作者:Addison N. Desnoyer、Eric G. Bowes、Brian O. Patrick、Jennifer A. Love
DOI:10.1021/jacs.5b06735
日期:2015.10.14
frequently invoked as reactive intermediates in catalytic reactions of epoxides using nickel, but have never been isolated or experimentally observed in these transformations. Herein, we report the preparation of a series of well-defined nickelaoxetanes formed via the oxidative addition of nickel(0) with epoxides featuring ketones. The stereochemistry of the products is retained, which has not yet been reported