Dell'Amico Luca, Vega-Peñaloza Alberto, Cuadros Sara, Melchiorre Paolo
ICIQ-Institute of Chemical Research of Catalonia, Barcelona Institute of Science and Technology, Avenida Països Catalans 16, 43007, Tarragona, Spain.
ICREA-Catalan Institution for Research and Advanced Studies, Passeig Lluís Companys 23, 08010, Barcelona, Spain.
Angew Chem Int Ed Engl. 2016 Mar 1;55(10):3313-7. doi: 10.1002/anie.201509472. Epub 2016 Jan 21.
The photoenolization/Diels-Alder strategy offers straightforward access to synthetically valuable benzannulated carbocyclic products. This historical light-triggered process has never before succumbed to efforts to develop an enantioselective catalytic approach. Herein, we demonstrate how asymmetric organocatalysis provides simple yet effective catalytic tools to intercept photochemically generated hydroxy-o-quinodimethanes with high stereoselectivity. We used a chiral organic catalyst, derived from natural cinchona alkaloids, to activate maleimides toward highly stereoselective Diels-Alder reactions. An unconventional mechanism of stereocontrol is operative, wherein the organocatalyst is actively involved in both the photochemical pathway, by leveraging the formation of the reactive photoenol, and the stereoselectivity-defining event.
光烯醇化/狄尔斯-阿尔德策略为合成具有重要价值的苯并稠合碳环产物提供了直接途径。这一具有历史意义的光触发过程此前从未成功实现对映选择性催化方法的开发。在此,我们展示了不对称有机催化如何提供简单而有效的催化工具,以高立体选择性拦截光化学产生的羟基邻醌二甲烷。我们使用了一种源自天然金鸡纳生物碱的手性有机催化剂,来活化马来酰亚胺以进行高立体选择性的狄尔斯-阿尔德反应。一种非常规的立体控制机制在起作用,其中有机催化剂通过利用反应性光烯醇的形成,积极参与光化学途径以及决定立体选择性的过程。