Assembly of Spirooxindole Derivatives Containing Four Consecutive Stereocenters via Organocatalytic Michael–Henry Cascade Reactions
作者:Klaus Albertshofer、Bin Tan、Carlos F. Barbas
DOI:10.1021/ol300441z
日期:2012.4.6
A novel organocatalytic strategy for the synthesis of highly substituted spirocyclopentaneoxindoles was developed employing simple nitrostyrenes and 3-substituted oxindoles as starting materials. Michael–Henry cascadereactions, enabled through cinchona alkaloid organocatalysis, provided products in high yield and excellent enantioselectivity in a single step.
Control of Remote Stereochemistry in the Synthesis of Spirocyclic Oxindoles: Vinylogous Organocascade Catalysis
作者:Xu Tian、Paolo Melchiorre
DOI:10.1002/anie.201301017
日期:2013.5.10
Remote control: The title reaction facilitates the synthesis of complex chiral molecules while selectively forging multiple stereocenters at distant positions, namely five and six bond lengths away from the catalyst chiral fragment (see scheme; Boc=tert‐butoxycarbonyl). The potential of the strategy is demonstrated through the one‐step preparation of spirocyclopentane oxindoles having four contiguous
Assembly of Spirooxindole Derivatives via Organocatalytic Iminium-Enamine Cascade Reactions
作者:Klaus Albertshofer、Kimberly E. Anderson、Carlos F. Barbas
DOI:10.1021/ol302876c
日期:2012.12.7
The assembly of complex spirocyclopentaneoxindoles via a novel organocatalytic iminium-enamine cascade process is reported. Reactions between 3-substituted oxindoles and alpha,beta-unsaturated aldehydes catalyzed by second generation prolinol ethers provided the desired products in high yield with excellent levels of enantioselectivity in a single step.
Asymmetric Michael Addition of Oxindoles to Allenoate Catalyzed by<i>N</i>-Acyl Aminophosphine: Construction of Functionalized Oxindoles with Quaternary Stereogenic Center
作者:Jinhao Chen、Yuepeng Cai、Gang Zhao
DOI:10.1002/adsc.201300695
日期:2014.2.10
AbstractA novel reaction between ethyl allenoate and oxindoles that enables the asymmetric synthesis of 3,3‐bisubstituted oxindoles with our previously established bifunctional N‐acyl aminophosphine catalysts is reported. These products bearing a chiral quaternary carbon center at the C‐3 position of the oxindoles may have potential significance in the synthesis of related structures. The best performance of these processes provides adducts with 92% yield and 94% ee.magnified image