Asymmetric Cross [10+2] Cycloadditions of 2‐Alkylidene‐1‐indanones and Activated Alkenes under Phase‐Transfer Catalysis
作者:Yang Yang、Ying Jiang、Wei Du、Ying‐Chun Chen
DOI:10.1002/chem.201904930
日期:2020.2.6
have been employed in diverse challenging higher-order cycloaddition reactions. Here, the first chemoselective and asymmetric cross [10+2] cycloaddition reaction between activated 2-alkylidene-1-indanones and a variety of electron-deficient alkenes has been developed, relying on the in situ generation of dearomative 1-hydroxyl isobenzofulvene anion intermediates under the catalysis of a newly designed
An efficient organocatalytic Michael-aldol cascade reaction for the asymmetric synthesis of spirocyclic oxindole derivatives fused with tetrahydrothiophenes has been developed through a formal [3+2] annulation strategy.
catalysts displaying various effects that noticeably differ in terms of steric hindrance and electron demand; (ii) employed α-alkylidene oxindoles decorated with different substituents on the aromatic ring (11a–g), the exocylic double bond (11h–l), and the amide moiety (11m–v). The observed results suggest that the modification of the electron-withdrawing group (EWG) weakly conditions the overall outcomes
考虑到我们实验室开发的缺电子烯烃有机催化环氧化反应的假设反应机理,我们研究了能够对安装在底物/催化剂/氧化剂内部的 H 键网络产生积极影响的关键因素。为了这个目标,我们已经: (i) 测试了一些催化剂,显示出在空间位阻和电子需求方面明显不同的各种效果;(ii) 使用在芳环 (11a-g)、环外双键 (11h-l) 和酰胺部分 (11m-v) 上装饰有不同取代基的 α-亚烷基羟吲哚。观察到的结果表明,吸电子基团 (EWG) 的修饰对整体结果的影响很小,相反,强烈的影响明确归因于 N 保护或 N 未保护的内酰胺框架。
Visible light induced intermolecular [2+2]-cycloaddition reactions of 3-ylideneoxindoles through energy transfer pathway
A highlydiastereoselective and regioselective [2+2]-cycloaddition reaction of 3-ylideneoxindoles has been accomplished using visible light photocatalysis. This visible light photocatalytic protocol allows an expedient access to diversely functionalized and structurally constrained oxindolederivatives containing two spirocycles and four stereogenic centers, including two all-carbon quaternary centers