A Unified Catalytic Asymmetric (4+1) and (5+1) Annulation Strategy to Access Chiral Spirooxindole‐Fused Oxacycles
作者:Min Gao、Yanshu Luo、Qianlan Xu、Yukun Zhao、Xiangnan Gong、Yuanzhi Xia、Lin Hu
DOI:10.1002/anie.202105282
日期:2021.9
A unified catalyticasymmetric (N+1) (N=4, 5) annulation reaction of oxindoles with bifunctional peroxides has been achieved in the presence of a chiral phase-transfer catalyst (PTC). This general strategy utilizes peroxides as unique bielectrophilic four- or five-atom synthons to participate in the C−C and the subsequent umpolung C−O bond-forming reactions with one-carbon unit nucleophiles, thus providing
在手性相转移催化剂 (PTC) 的存在下,已经实现了羟吲哚与双官能过氧化物的统一催化不对称 ( N +1) ( N =4, 5) 环化反应。这种通用策略利用过氧化物作为独特的双亲电四原子或五原子合成子参与 C−C 和随后与单碳单元亲核试剂的 umpolung C−O 键形成反应,从而提供了一种独特的方法来获得有价值的手性螺吲哚-四氢呋喃和-四氢吡喃在温和条件下具有良好的产率和高对映选择性。进行 DFT 计算以合理化高对映选择性的起源。还证明了所得产物的克级合成和合成效用。
Stéréospécificité de l'addition de Michael d'ènethiolates avec les énones acycliques
作者:Kafui Kpegba、Patrick Metzner、Rosé Rakotonirina
DOI:10.1016/s0040-4020(01)80066-1
日期:1989.1
E-enones (3-penten-2-one, chalcone) occurs with high stereospecificity: anti/syn product ratios are identical to the cis/trans enethiolate ratios. A pseudo-cyclic transition state is proposed with substituents of the enone C-C doublebond occupying favorable equatorial positions. The 1,4-addition reaction is kineticaly controlled. In contrast to ester enolates, enethiolates allow the use of enones without
Reduction of Activated Alkenes by P
<sup>III</sup>
/P
<sup>V</sup>
Redox Cycling Catalysis
作者:Lars Longwitz、Thomas Werner
DOI:10.1002/anie.201912991
日期:2020.2.10
using a phosphetane oxide catalyst in the presence of a simple organosilane as the terminal reductant and water as the hydrogen source. Quantitative hydrogenation was observed when 1.0 mol % of a methyl‐substituted phosphetane oxide was employed as the catalyst. The procedure is highly selective towards activated double bonds, tolerating a variety of functional groups that are usually prone to reduction
Minimization of Back‐Electron Transfer Enables the Elusive sp
<sup>3</sup>
C−H Functionalization of Secondary Anilines
作者:Huaibo Zhao、Daniele Leonori
DOI:10.1002/anie.202100051
日期:2021.3.29
Anilines are some of the most used class of substrates for application in photoinduced electron transfer. N,N‐Dialkyl‐derivatives enable radicalgenerationα to the N‐atom by oxidation followed by deprotonation. This approach is however elusive to monosubstituted anilines owing to fast back‐electron transfer (BET). Here we demonstrate that BET can be minimised by using photoredox catalysis in the presence
苯胺是光诱导电子转移中最常用的一类底物。 N,N-二烷基衍生物能够通过氧化然后去质子化使 N 原子产生自由基 α。然而,由于快速反电子转移(BET),这种方法对于单取代苯胺来说难以捉摸。在这里,我们证明了在外源烷基胺存在的情况下使用光氧化还原催化可以最大限度地减少 BET。这种方法协同帮助苯胺 SET 氧化,然后加速随后的去质子化。通过这种方式,现在可以生成 α-苯胺烷基自由基,并且这些物质可以在一般意义上用于实现不同的 sp 3 C−H 官能化。
Catalytic alkylation of remote C–H bonds enabled by proton-coupled electron transfer
作者:Gilbert J. Choi、Qilei Zhu、David C. Miller、Carol J. Gu、Robert R. Knowles
DOI:10.1038/nature19811
日期:2016.11
unfunctionalized amides to direct the formation of new C–C bonds. Given the prevalence of amides in pharmaceuticals and natural products, we anticipate that this method will simplify the synthesis and structural elaboration of amine-containing targets. Moreover, this study demonstrates that concerted proton-coupled electron transfer can enable homolytic activation of common organic functional groups