Photoredox‐Catalyzed Cyclopropanation of 1,1‐Disubstituted Alkenes via Radical‐Polar Crossover Process
作者:Wenping Luo、Yi Yang、Yewen Fang、Xinxin Zhang、Xiaoping Jin、Guicai Zhao、Li Zhang、Yan Li、Wanli Zhou、Tingting Xia、Bin Chen
DOI:10.1002/adsc.201900708
日期:2019.9.17
1‐disubstituted alkenes via radical addition‐anionic cyclization cascade has been successfully developed. Another new protocol based on photocatalytic allylation and cyclopropanation cascade was also described between allylic halide and halomethyl radical. In addition to the successful use of bis‐catecholato silicates as the alkyl radical precursors, the acyl and alkyl radicals derived from 1,4‐dihydropyridines
已成功开发了通过自由基加成-阴离子环化级联反应对1,1-二取代烯烃进行光氧化还原中性催化的环丙烷化反应。还描述了另一种基于光催化烯丙基化和环丙烷化级联的新方案,介于烯丙基卤化物和卤代甲基之间。除了成功地使用双邻苯二酚硅酸盐作为烷基自由基前体外,从1,4-二氢吡啶衍生的酰基和烷基也参与了该自由基-极性交叉过程。竞争实验显示的3-外- TET环化的模式优于4-外型和5-外型环化模式,从而允许选择性3-外型- TET环化。在溴甲基自由基与均烯丙基(假)卤化物的反应中,已经证明了溴化物比氯化物和甲苯磺酸盐优越的核沉着特征。该新协议的特点是其氧化还原中性过程,广泛的底物范围,温和的条件以及良好的功能基团相容性。