Spin-Selective Generation of Triplet Nitrenes: Olefin Aziridination through Visible-Light Photosensitization of Azidoformates
作者:Spencer O. Scholz、Elliot P. Farney、Sangyun Kim、Desiree M. Bates、Tehshik P. Yoon
DOI:10.1002/anie.201510868
日期:2016.2.5
but their direct photochemical activation can result in competitive formation of aziridination and allylic amination products. Herein, we show that visible‐light‐activated transition‐metal complexes can be triplet sensitizers that selectively produce aziridines through the spin‐selective photogeneration of triplet nitrenes from azidoformates. This approach enables the aziridination of a wide range of
Intermediates in the epoxidation of alkenes by cytochrome P-450 models. 2. Use of the trans-2,trans-3-diphenylcyclopropyl substituent in a search for radical intermediates
作者:Angelo J. Castellino、Thomas C. Bruice
DOI:10.1021/ja00230a039
日期:1988.10
Catalyse par les complexes: [(F 20 TPP)Fe(III)(Cl)], [(Cl 8 TPP)Fe(III)(Cl)], et [(Cl 8 TPP)Mn(III)(OH)]. (F 20 TPP=meso-tetrakis-pentafluorophenyl porphyrine, Cl 8 TPP=meso-tetrakis-[dichloro-2,6 phenyl] porphyrine)
Mechanism of Alcohol Oxidation Mediated by Copper(II) and Nitroxyl Radicals
作者:Bradford L. Ryland、Scott D. McCann、Thomas C. Brunold、Shannon S. Stahl
DOI:10.1021/ja5070137
日期:2014.8.27
classes of radical-probe substrates shows that long-lived radicals are not formed in the reaction. DFT computational studies support this conclusion. A bimolecular pathway involving hydrogen-atom-transfer from a Cu(II)-alkoxide to a nitroxylradical is higher in energy than hydrogen transfer from a Cu(II)-alkoxide to a coordinated nitroxyl species. The data presented here reconcile a collection of
2,2'-联吡啶连接的铜配合物与 TEMPO(2,2,6,6-四甲基哌啶-N-氧基)结合,是有氧醇氧化的高效催化剂。关于由 Cu(II) 和 TEMPO 介导的醇氧化机制存在相当多的不确定性和争论。在这里,我们报告了实验和密度泛函理论 (DFT) 计算研究,这些研究区分了许多先前提出的机械途径。各类自由基探针底物的氧化表明反应中没有形成长寿命的自由基。DFT 计算研究支持这一结论。涉及从 Cu(II)-醇盐到硝酰基自由基的氢原子转移的双分子途径的能量高于从 Cu(II)-醇盐到配位硝酰基物质的氢转移。此处提供的数据协调了先前在文献中报告的各种看似矛盾的实验和计算数据的集合。由此产生的类似 Oppenauer 的反应途径进一步解释了不同类别醇(苄醇与脂肪醇和伯醇与仲醇)的相对反应性的实验趋势,以及在 TEMPO 和双环硝酰基之间观察到的不同反应性,例如 ABNO (ABNO = 9 -氮杂双环[3
Chemical Hermaphroditism: The Potential of the Cr(CO)<sub>3</sub> Moiety To Stabilize Transition States and Intermediates with Anionic, Cationic, or Radical Character at the Benzylic Position
作者:Craig A. Merlic、Joseph C. Walsh、Dean J. Tantillo、K. N. Houk
DOI:10.1021/ja983934k
日期:1999.4.1
stabilized by Cr(CO)3 complexation. This unusual characteristic of chromium arenes has been the subject of many synthetic, spectroscopic, and physical organic studies over the last four decades. The effect of Cr(CO)3 on benzylic radicals has received comparatively little attention, however. In this report, cyclopropylcarbinyl anions, cations, and radicals substituted with both phenyl and Cr(CO)3-phenyl
<i>In Situ</i> Generation of Zinc Carbenoids from Diazo Compounds and Zinc Salts: Asymmetric Synthesis of 1,2,3-Substituted Cyclopropanes
作者:Sébastien R. Goudreau、André B. Charette
DOI:10.1021/ja9074776
日期:2009.11.4
first enantioselective cyclopropanation of alkenes usingzinccarbenoids generated in situ from diazo compounds and zinc salts is reported. This new method allows the highly enantio- and diastereoselective synthesis of 1,2,3-substituted cyclopropanes via aryl-substituted carbenoids. The first Simmons-Smith reaction using a catalytic amount of zinc to generate enantioenriched cyclopropane is also reported