Asymmetric Organocatalytic Epoxidation of α,β-Unsaturated Aldehydes with Hydrogen Peroxide
作者:Mauro Marigo、Johan Franzén、Thomas B. Poulsen、Wei Zhuang、Karl Anker Jørgensen
DOI:10.1021/ja051808s
日期:2005.5.1
The first asymmetricorganocatalytic epoxidation of α,β-unsaturatedaldehydes is presented. A chiral bisaryl−silyl-protected pyrrolidine acts as a very selective epoxidation organocatalyst using simple oxidation agents, such as hydrogen peroxide and tert-butyl hydroperoxide. The asymmetric epoxidation reactions proceed under environmental friendly reaction condition in, for example, water mixtures
介绍了 α,β-不饱和醛的第一个不对称有机催化环氧化反应。手性双芳基-甲硅烷基保护的吡咯烷使用简单的氧化剂(如过氧化氢和叔丁基过氧化氢)作为一种非常有选择性的环氧化有机催化剂。不对称环氧化反应在环境友好的反应条件下进行,例如,在醇的水混合物中,反应的范围通过以高产率和对映选择性 > 94% ee 形成光学活性的 α,β-环氧醛来证明。此外,还介绍了通过柠檬醛的不对称环氧化从螨虫直接合成性信息素。
Fluorinated Organocatalysts for the Enantioselective Epoxidation of Enals: Molecular Preorganisation by the Fluorine-Iminium Ion Gauche Effect
作者:Eva-Maria Tanzer、Lucie E. Zimmer、W. Bernd Schweizer、Ryan Gilmour
DOI:10.1002/chem.201201316
日期:2012.9.3
The fluorine‐iminium ion gauche effect is triggered upon union of a secondary β‐fluoroamine and an α,β‐unsaturated aldehyde, providing a useful strategy for controlling the molecular topology of intermediates that are central to organocatalytic processes. The β‐fluoroamine (S)‐2‐(fluorodiphenylmethyl)pyrrolidine (1) is an effective catalyst for the enantioselectiveepoxidation of α,β‐unsaturated aldehydes
Sespendole is an indole sesquiterpene alkaloid bearing two isoprenyl groups, one of which is highly oxidized. Herein, we disclose an eight-step synthesis of the aromatic fragment of sespendole in an optically pure form, starting from 4-bromo-2-fluoronitrobenzene. The key steps were a Claisen rearrangement at room temperature for introduction of the prenyl group and a coupling between the dianion generated
The asymmetric synthesis of β-lactam antibiotics-v. Application of chiral α,β-epoxyimines in ketene-imine cycloaddition reactions leading to homochiral 3-aminoazetidinones.
作者:David A. Evans、J.Michael Williams
DOI:10.1016/s0040-4039(00)80680-2
日期:1988.1
Asymmetric Counteranion-Directed Catalysis for the Epoxidation of Enals