Redox-Neutral Photocatalytic Cyclopropanation via Radical/Polar Crossover
作者:James P. Phelan、Simon B. Lang、Jordan S. Compton、Christopher B. Kelly、Ryan Dykstra、Osvaldo Gutierrez、Gary A. Molander
DOI:10.1021/jacs.8b05243
日期:2018.6.27
A benchtop stable, bifunctional reagent for the redox-neutral cyclopropanation of olefins has been developed. Triethylammonium bis(catecholato)iodomethylsilicate can be readily prepared on multigram scale. Using this reagent in combination with an organic photocatalyst and visible light, cyclopropanation of an array of olefins, including trifluoromethyl- and pinacolatoboryl-substituted alkenes, can
The hydrodefluorination of CF3-substituted alkenes can be catalyzed by a nickel(II) hydride bearing a pincer ligand. The cata-lyst loading can be as low as 1 mol%. gem-Difluoroalkenes containing a number of functional groups can be formed in good to excellent yields, by a radical mechanism initiated by H• transfer from the nickel hydride. The relative reactivity of various substrates supports the proposed
CF3 取代烯烃的加氢脱氟可以由带有钳状配体的镍 (II) 氢化物催化。催化剂负载量可以低至 1 mol%。通过从氢化镍中转移 H• 引发的自由基机制,可以以良好到极好的产率形成含有许多官能团的 gem-二氟烯烃。各种底物的相对反应性支持所提出的机制,TEMPO 捕获实验也是如此。
Metal-free defluorinative arylation of trifluoromethyl alkenes <i>via</i> photoredox catalysis
作者:Rebecca J. Wiles、James P. Phelan、Gary A. Molander
DOI:10.1039/c9cc04265b
日期:——
photoredox-mediated processes are not amenable to aryl radical addition to trifluoromethyl alkenes. A metal-free, functional group-tolerant method for the preparation of benzylic gem-difluoroalkenes is described. Halogen atom abstraction from (hetero)aryl halides generates aryl radicals that undergo a defluorinative arylation of α-trifluoromethyl alkenes, tolerating electronically disparate aryl radicals and α-trifluoromethyl
Efficient Decarboxylative/Defluorinative Alkylation for the Synthesis of
<scp>
<i>gem</i>
‐Difluoroalkenes
</scp>
through an
<scp>
S
<sub>N</sub>
2
</scp>
’‐Type Route
作者:Wei‐Long Xing、Jia‐Xin Wang、Ming‐Chen Fu、Yao Fu
DOI:10.1002/cjoc.202100709
日期:2022.2
An efficientdecarboxylative/defluorinativealkylation for synthesizing gem-difluoroalkenes is described, providing a general method for installation of the challenging alkyl fragments containing α-electron-withdrawing groups into α-trifluoromethyl alkenes. Mechanistic studies suggest that this process involves an SN2′-type synthetic route in the absence of transition-metal catalysts or photocatalysis
描述了一种用于合成偕二氟烯烃的有效脱羧/脱氟烷基化反应,为将含有 α-吸电子基团的具有挑战性的烷基片段安装到 α-三氟甲基烯烃中提供了一种通用方法。机理研究表明,该过程涉及在没有过渡金属催化剂或光催化的情况下的 S N 2' 型合成路线。此外,该协议可以很容易地扩大规模,并成功应用于生物活性分子的修饰,从而补充了获得结构通用的gem-二氟烯烃的方法。
Synthesis of <i>gem</i>-Difluoroallylboronates via FeCl<sub>2</sub>-Catalyzed Boration/β-Fluorine Elimination of Trifluoromethyl Alkenes
作者:Yang Liu、Yuhan Zhou、Yilong Zhao、Jingping Qu
DOI:10.1021/acs.orglett.7b00168
日期:2017.2.17
The first ferrous chloride catalyzed boration/β-fluorine elimination of trifluoromethyl alkenes is described. Thus, a full range of gem-difluoroallylboronates were obtained in high yield under mild conditions. As an important fluorinated building block, gem-difluoroallylboronate can be readily converted into diverse difluoro-substituted species.