40745-20-8Relevant academic research and scientific papers
THE INFLUENCE OF ALKOXY GROUPS ON THE NUCLEOPHILICITY OF ALKYL RADICALS
Giese, Bernd,Dupuis, Jacques,Hasskerl, Thomas,Meixner, Juergen
, p. 703 - 706 (1983)
One alkoxy substituent increases the nucleophilicity of alkyl radicals in addition reactions at alkenes more than three methyl groups.
Alkyl-GeMe3: Neutral Metalloid Radical Precursors upon Visible-Light Photocatalysis
Wei, Li-Pu,Xiao, Bin,Xu, Qing-Hao
, (2022/02/17)
Single-electron transfer (SET) oxidation of ionic hypervalent complexes, in particular alkyltrifluoroborates (Alkyl-BF3?) and alkylbis(catecholato)silicates (Alkyl-Si(cat)2?), have contributed substantially to alkyl radical generation compared to alkali or alkaline earth organometallics because of their excellent activity–stability balance. Herein, another proposal is reported by using neutral metalloid compounds, Alkyl-GeMe3, as radical precursors. Alkyl-GeMe3 shows comparable activity to that of Alkyl-BF3? and Alkyl-Si(cat)2? in radical addition reactions. Moreover, Alkyl-GeMe3 is the first successful group 14 tetraalkyl nucleophile in nickel-catalyzed cross-coupling. Meanwhile, the neutral nature of these organogermanes offset the limitation of ionic precursors in purification and derivatization. A preliminary mechanism study suggests that an alkyl radical is generated from a tetraalkylgermane radical cation with the assistance of a nucleophile, which may also result in the development of more non-ionic alkyl radical precursors with a metalloid center.
A General Organocatalytic System for Electron Donor-Acceptor Complex Photoactivation and Its Use in Radical Processes
De Pedro Beato, Eduardo,Melchiorre, Paolo,Spinnato, Davide,Zhou, Wei
supporting information, p. 12304 - 12314 (2021/08/20)
We report herein a modular class of organic catalysts that, acting as donors, can readily form photoactive electron donor-acceptor (EDA) complexes with a variety of radical precursors. Excitation with visible light generates open-shell intermediates under mild conditions, including nonstabilized carbon radicals and nitrogen-centered radicals. The modular nature of the commercially available xanthogenate and dithiocarbamate anion organocatalysts offers a versatile EDA complex catalytic platform for developing mechanistically distinct radical reactions, encompassing redox-neutral and net-reductive processes. Mechanistic investigations, by means of quantum yield determination, established that a closed catalytic cycle is operational for all of the developed radical processes, highlighting the ability of the organic catalysts to turn over and iteratively drive every catalytic cycle. We also demonstrate how the catalysts' stability and the method's high functional group tolerance could be advantageous for the direct radical functionalization of abundant functional groups, including aliphatic carboxylic acids and amines, and for applications in the late-stage elaboration of biorelevant compounds and enantioselective radical catalysis.
Catalyst-Free Decarboxylation of Carboxylic Acids and Deoxygenation of Alcohols by Electro-Induced Radical Formation
Chen, Xiaoping,Luo, Xiaosheng,Peng, Xiao,Guo, Jiaojiao,Zai, Jiantao,Wang, Ping
, p. 3226 - 3230 (2020/02/27)
Electro-induced reduction of redox active esters and N-phthalimidoyl oxalates derived from naturally abundant carboxylic acids and alcohols provides a sustainable and inexpensive approach to radical formation via undivided electrochemical cells. The resulting radicals are trapped by an electron-poor olefin or hydrogen atom source to furnish the Giese reaction or reductive decarboxylation products, respectively. A broad range of carboxylic acid (1°, 2°, and 3°) and alcohol (2° and 3°) derivatives are applicable in this catalyst-free reaction, which tolerated a diverse range of functional groups. This method features simple operation, is a sustainable platform, and has broad application.
Cerium-Catalyzed C-H Functionalizations of Alkanes Utilizing Alcohols as Hydrogen Atom Transfer Agents
An, Qing,Chen, Yuegang,Liu, Weimin,Pan, Hui,Wang, Xin,Wang, Ziyu,Zhang, Kaining,Zuo, Zhiwei
supporting information, p. 6216 - 6226 (2020/04/27)
Modern photoredox catalysis has traditionally relied upon metal-to-ligand charge-transfer (MLCT) excitation of metal polypyridyl complexes for the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C-H amination and the alkylation of hydrocarbons, this reaction manifold has enabled the facile use of abundant alcohols as practical and selective hydrogen atom transfer (HAT) agents via the direct access of energetically challenging alkoxy radicals. Furthermore, the LMCT excitation event has been investigated through a series of spectroscopic experiments, revealing a rapid bond homolysis process and an effective production of alkoxy radicals, collectively ruling out the LMCT/homolysis event as the rate-determining step of this C-H functionalization.
Synthesis of lactate derivatives via reductive radical addition to α-oxyacrylates
Diccianni, Justin B.,Chin, Mason,Diao, Tianning
, p. 4180 - 4185 (2019/05/15)
Lactate derivatives are important synthetic precursors to a variety of pharmaceutical products. Previously reported methods to prepare lactates require multiple steps or have limited scopes. Herein, we report a Ni-catalyzed reductive addition of a variety
Carbonylation of Alkyl Radicals Derived from Organosilicates through Visible-Light Photoredox Catalysis
Cartier, Alex,Levernier, Etienne,Corcé, Vincent,Fukuyama, Takahide,Dhimane, Anne-Lise,Ollivier, Cyril,Ryu, Ilhyong,Fensterbank, Louis
supporting information, p. 1789 - 1793 (2019/01/09)
Primary, secondary, and tertiary alkyl radicals formed by the photocatalyzed oxidation of organosilicates underwent efficient carbonylation with carbon monoxide (CO) to give a variety of unsymmetrical ketones. This study introduces the possibility of radi
Visible Light Uranyl Photocatalysis: Direct C-H to C-C Bond Conversion
Capaldo, Luca,Merli, Daniele,Fagnoni, Maurizio,Ravelli, Davide
, p. 3054 - 3058 (2019/03/26)
Uranyl nitrate hexahydrate performs as an efficient photocatalyst in the direct C-H to C-C bond conversion under blue light irradiation via hydrogen atom transfer (HAT). This uranyl salt enables the remarkable smooth functionalization of unactivated (cycl
Selective Palladium-Catalyzed Carbonylation of Alkynes: An Atom-Economic Synthesis of 1,4-Dicarboxylic Acid Diesters
Liu, Jiawang,Dong, Kaiwu,Franke, Robert,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
supporting information, p. 10282 - 10288 (2018/08/03)
A class of novel diphosphine ligands bearing pyridine substituents was designed and synthesized for the first time. The resulting palladium complexes of L1 allow for chemo- and regioselective dialkoxycarbonylation of various aromatic and aliphatic alkynes affording a wide range of 1,4-dicarboxylic acid diesters in high yields and selectivities. Kinetic studies suggest the generation of 1,4-dicarboxylic acid diesters via cascade hydroesterification of the corresponding alkynes. Based on these investigations, the chemo- and regioselectivities of alkyne carbonylations can be controlled as shown by switching the ligand from L1 to L3 or L9 to give α,β-unsaturated esters.
Hydrogen Atom Transfer Reactions via Photoredox Catalyzed Chlorine Atom Generation
Rohe, Samantha,Morris, Avery O.,McCallum, Terry,Barriault, Louis
supporting information, p. 15664 - 15669 (2018/10/26)
The selective functionalization of chemically inert C?H bonds remains to be fully realized in achieving organic transformations that are redox-neutral, waste-limiting, and atom-economical. The catalytic generation of chlorine atoms 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 chlorine atoms as a new opportunity for access to a wide variety of hydrogen atom transfer (HAT) reactions owing to the high stability of HCl. The discovery of the photoredox mediated generation of chlorine atoms with Ir-based polypyridyl complex, [Ir(dF(CF3)ppy)2(dtbbpy)]Cl, under blue LED irradiation is reported.
