Regioselective C-2 or C-5 Direct Arylation of Pyrroles with Aryl Bromides using a Ligand-Free Palladium Catalyst
作者:Julien Roger、Henri Doucet
DOI:10.1002/adsc.200900196
日期:——
acetyl or ester at the C-2 position of the pyrrole is tolerated. This environmentally attractive procedure has also been found to be tolerant to a very wide variety of functional groups on the arylbromides such as formyl, acetyl, propionyl, ester, nitrile, nitro, fluoro, methoxy, amino or trifluoromethyl.
Direct Arylation of Pyrroles via Indirect Electroreductive C–H Functionalization Using Perylene Bisimide as an Electron-Transfer Mediator
作者:Guoquan Sun、Shuya Ren、Xinhai Zhu、Manna Huang、Yiqian Wan
DOI:10.1021/acs.orglett.5b03581
日期:2016.2.5
The indirect electroreductive coupling of aryl halides and pyrroles was successfully conducted using a catalytic amount of perylenebisimide as a mediator in 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide ([EMIM]NTf2)/DMSO.
New Pd-NHC complexes have been synthesized and employed for palladium-catalyzed directarylation of pyrrolederivatives by using electron-deficient aryl chlorides as coupling partners. The desired coupling products were obtained in moderate to good yields by using 1 mol % of these air-stable palladium complexes. This is an advantage compared to the procedures employing air-sensitive phosphines, which
Anthraquinones as Photoredox Catalysts for the Reductive Activation of Aryl Halides
作者:Javier I. Bardagi、Indrajit Ghosh、Matthias Schmalzbauer、Tamal Ghosh、Burkhard König
DOI:10.1002/ejoc.201701461
日期:2018.1.10
none. The resulting aryl radicalanions fragment into halide anions and aryl radicals, which react in hydrogenabstraction or C-C bond forming reactions. The active photocatalyst is generated from 1,8-dihydroxyanthraquinone by photoinduced single electron reduction to the radicalanion or subsequent protonation and further reduction (or vice versa) to the semiquinone anion. Subsequent visible light
Transforming Non-innocent Phenalenyl to a Potent Photoreductant: Captivating Reductive Functionalization of Aryl Halides through Visible-Light-Induced Electron Transfer Processes
作者:Vishali Pathania、Vishal Jyoti Roy、Sudipta Raha Roy
DOI:10.1021/acs.joc.2c02241
日期:2022.12.16
utilizing the empty NBMO in the presence of a base to form a radicalanion which, upon photoexcitation, behaves as a stronger reductant and accomplishes the cleavage of strong C–X (X = Cl, Br, I) bonds under milder reaction conditions. The base was found to be involved in a dual role of electron and hydrogen atom donor. Further, the aryl radical formed by the homolysis of C–X bonds in this technique was
在此,我们建立了一种基于苯并烯基的分子支架,它作为一种有效的光还原剂,在存在碱基的情况下利用空的 NBMO 形成一个自由基阴离子,该阴离子在光激发后表现为更强的还原剂并完成强 C- 的裂解。 X (X = Cl, Br, I) 在较温和的反应条件下结合。发现该碱基具有电子和氢原子供体的双重作用。此外,在该技术中由 C-X 键均裂形成的芳基被捕获为 C sp2 –C sp2与未活化的芳烃偶联。phenalenyl 基催化体系的光还原效力进一步扩展到 C-P 以及 C-B 键形成反应。EPR 和寿命研究揭示了持久性自由基的形成,该自由基具有足够的寿命以通过 PET 机制参与反应。不同的光谱技术与 DFT 计算相结合,被用于表征活性催化物种和阐明可能的机理途径。这不仅是将苯萘基用作光还原剂的初步报告,而且还为具有挑战性的室温芳基卤化物还原功能化提供了一种完全不含金属(碱金属和过渡金属)的方法。