Direct Photoredox‐Catalyzed Reductive Difluoromethylation of Electron‐Deficient Alkenes
作者:Xiao‐Jun Tang、Zuxiao Zhang、William R. Dolbier
DOI:10.1002/chem.201504363
日期:2015.12.21
Photoredox‐catalyzed reductivedifluoromethylation of electron‐deficient alkenes was achieved in one step under tin‐free, mild and neutral conditions. This protocol affords a facile method to introduce RCF2 (R=H, Ph, Me, and CH2N3) groups at sites β to electron‐withdrawing groups. It was found that TTMS (tris(trimethylsilyl)silane) served nicely as both the H‐atom donor and the electron donor in the
在缺锡,温和和中性的条件下,一步一步就可以完成缺氧烯烃的光氧化还原催化的还原性二氟甲基化反应。该方案提供了一种简便的方法,可将β位的RCF 2(R = H,Ph,Me和CH 2 N 3)基团引入吸电子基团。发现TTMS(三(三甲基甲硅烷基)硅烷)在催化循环中既可以作为氢原子供体,也可以作为电子供体。实验和DFT计算结果提供了RCF 2(R = H,Ph,Me)自由基本质上亲核的证据。
Rh(III)-Catalyzed Decarboxylative Coupling of Acrylic Acids with Unsaturated Oxime Esters: Carboxylic Acids Serve as Traceless Activators
作者:Jamie M. Neely、Tomislav Rovis
DOI:10.1021/ja412444d
日期:2014.2.19
α,β-Unsaturated carboxylic acids undergo Rh(III)-catalyzed decarboxylative coupling with α,β-unsaturated O-pivaloyl oximes to provide substituted pyridines in good yield. The carboxylic acid, which is removed by decarboxylation, serves as a traceless activating group, giving 5-substituted pyridines with very high levels of regioselectivity. Mechanistic studies rule out a picolinic acid intermediate
Divergent Amine-Catalyzed [4 + 2] Annulation of Morita–Baylis–Hillman Allylic Acetates with Electron-Deficient Alkenes
作者:Silong Xu、Rongshun Chen、Zifeng Qin、Guiping Wu、Zhengjie He
DOI:10.1021/ol2032569
日期:2012.2.17
+ 2] annulation of Morita–Baylis–Hillman allylic acetates 2 with electron-deficientalkenes or diazenes has been developed for efficient syntheses of highly functionalized cyclohexenes, tetrahydropyridazines, and important spirocycles. This reaction unveils a new reactivity pattern of the intensely studied allyliccompounds 2 acting as a C4 synthon in Lewis base catalyzed annulationreactions and also
Allyldiisopropylphenylsilane as a synthetic equivalent of 2-hydroxy-1,3-dipole. Stereoselective synthesis of cyclopentanols
作者:Takahiko Akiyama、Eriko Hoshi、Satoru Fujiyoshi
DOI:10.1039/a804118k
日期:——
ZrCl4-Promoted [3 + 2] cycloaddition of allyldiisopropylphenylsilane to α,β-unsaturated ketones proceeds smoothly to afford silyl-substituted cyclopentanes highly stereoselectively. Oxidative cleavage of the carbon–silicon bond leads to stereoselective formation of cyclopentanols.
Visible light induced photoredox catalysis is an efficient method for radical activation. Herein, we report a photoredox catalyzed intramolecular radical-radical coupling reaction that proceeds through biradical intermediate. This protocol represents...