Catalytic Hydroetherification of Unactivated Alkenes Enabled by Proton‐Coupled Electron Transfer
作者:Elaine Tsui、Anthony J. Metrano、Yuto Tsuchiya、Robert R. Knowles
DOI:10.1002/anie.202003959
日期:2020.7.13
We report a catalytic, light‐driven method for the intramolecular hydroetherification of unactivated alkenols to furnish cyclic ether products. These reactions occur under visible‐light irradiation in the presence of an IrIII‐based photoredox catalyst, a Brønsted base catalyst, and a hydrogen‐atom transfer (HAT) co‐catalyst. Reactive alkoxy radicals are proposed as key intermediates, generated by direct
我们报告了一种催化光驱动方法,用于未活化烯醇的分子内加氢醚化以提供环醚产品。这些反应在 Ir III基光氧化还原催化剂、布朗斯台德碱催化剂和氢原子转移 (HAT) 助催化剂存在下在可见光照射下发生。反应性烷氧基被认为是关键中间体,是通过质子耦合电子转移机制直接均裂激活醇 O−H 键而产生的。该方法表现出广泛的底物范围和高官能团耐受性,并且适应多种烯烃取代模式。还提出了证明该催化系统扩展到碳醚化反应的结果。
Catalytic Carbocation Generation Enabled by the Mesolytic Cleavage of Alkoxyamine Radical Cations
作者:Qilei Zhu、Emily C. Gentry、Robert R. Knowles
DOI:10.1002/anie.201604619
日期:2016.8.16
weak C−O bond. Spontaneous scission results in the formation of the stable nitroxyl radical TEMPO. as well as a reactive carbocation intermediate that can be intercepted by a wide range of nucleophiles. Notably, this process occurs underneutralconditions and at comparatively mild potentials, enabling catalytic cation generation in the presence of both acid sensitive and easily oxidized nucleophilic
Hydrogen Atom Transfer Reactions via Photoredox Catalyzed Chlorine Atom Generation
作者:Samantha Rohe、Avery O. Morris、Terry McCallum、Louis Barriault
DOI:10.1002/anie.201810187
日期:2018.11.26
waste‐limiting, and atom‐economical. The catalytic generation of chlorineatoms from chloride ions is one of the most challenging redox processes, where the requirement of harsh and oxidizing reaction conditions renders it seldom utilized in synthetic applications. We report the mild, controlled, and catalytic generation of chlorineatoms as a new opportunity for access to a wide variety of hydrogen atom transfer
An efficient method for the Ullmann coupling of chloropyridines catalyzed by poly(N-vinylpyrrolidone) (PVP)-stabilized bimetallic Au–Pd alloy nanoclusters (NCs) under ambient conditions is demonstrated. The reaction does not occur with either gold or palladium single-metal clusters alone, nor with a physical mixture of the two metals. The experimental results indicate that the inclusion of Au as a nearest
Intermolecular Anti-Markovnikov Hydroamination of Unactivated Alkenes with Sulfonamides Enabled by Proton-Coupled Electron Transfer
作者:Qilei Zhu、David E. Graff、Robert R. Knowles
DOI:10.1021/jacs.7b11144
日期:2018.1.17
Here we report a catalytic method for the intermolecularanti-Markovnikovhydroamination of unactivated alkenes using primary and secondary sulfonamides. These reactions occur at room temperature under visible light irradiation and are jointly catalyzed by an iridium(III) photocatalyst, a dialkyl phosphate base, and a thiol hydrogen atom donor. Reaction outcomes are consistent with the intermediacy
在这里,我们报告了一种使用初级和次级磺酰胺对未活化烯烃进行分子间抗马尔科夫尼科夫加氢胺化的催化方法。这些反应在室温下在可见光照射下发生,并由铱 (III) 光催化剂、磷酸二烷基酯碱和硫醇氢原子供体共同催化。反应结果与通过磺酰胺 NH 键的质子耦合电子转移激活产生的 N 中心磺酰胺自由基的中间体一致。概述了反应的合成范围(> 60 个例子)和机械特征的研究。