Oxygenation of Styrenes Catalyzed by N-Doped Carbon Incarcerated Cobalt Nanoparticles
作者:Tomohiro Yasukawa、Shū Kobayashi
DOI:10.1246/bcsj.20190251
日期:2019.12.15
We found that cobalt nanoparticle catalysts supported on nitrogen-doped carbon could facilitate oxygenation of styrenes in a heterogeneous manner. Both the nitrogen dopant and cobalt species were e...
nBu4NI-catalyzed cross-coupling of benzyl and allylic compounds with N-hydroxyphthalimide for the synthesis of alkyloxyamines were realized for the first time.
Acid Is Key to the Radical-Trapping Antioxidant Activity of Nitroxides
作者:Evan A. Haidasz、Derek Meng、Riccardo Amorati、Andrea Baschieri、Keith U. Ingold、Luca Valgimigli、Derek A. Pratt
DOI:10.1021/jacs.6b00677
日期:2016.4.27
rapid combination of a nitroxide with an alkyl radical to yield an alkoxyamine that subsequently reacts with a peroxyl radical to eventually re-form the nitroxide. Herein, we offer evidence in favor of an alternative reaction mechanism involving the acid-catalyzed reaction of a nitroxide with a peroxyl radical to yield an oxoammonium ion followed by electron transfer from an alkyl radical to the oxoammonium
持久性二烷基硝基氧化物(例如,2,2,6,6-四甲基哌啶-1-氧基,TEMPO)在受阻胺光稳定剂 (HALS) 添加剂的活性中起核心作用,该添加剂可抑制消费品和工业品的(光)氧化降解产品。HALS 的公认机制包括一个催化循环,该循环涉及硝基氧化物与烷基自由基的快速结合以产生烷氧基胺,该烷氧基胺随后与过氧基自由基反应以最终重新形成硝基氧化物。在此,我们提供了支持替代反应机制的证据,该机制涉及硝基氧与过氧自由基的酸催化反应以产生氧代铵离子,然后电子从烷基自由基转移到氧代铵离子以重新形成氮氧化合物。在前期工作中,我们表明 TEMPO 在酸存在下以扩散控制的速率与过氧自由基反应。现在,我们表明 TEMPO 可以通过与烷基反应从其氧铵离子再生。我们已经确定,该反应被认为是 TEMPO 催化合成转化中的关键步骤,发生在 k ∼ 1-3 × 10(10) M(-1) s(-1) 中,从而使其能够与 O2
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
α-Chiral alkyl primaryamines are virtually universal synthetic precursors for all other α-chiral N-containing compounds ubiquitous in biological, pharmaceutical, and material sciences. The enantioselective amination of common alkyl halides with ammonia is appealing for potential rapid access to α-chiral primaryamines, but has hitherto remained rare due to the multifaceted difficulties in using ammonia