4696-23-5Relevant academic research and scientific papers
Iridium-catalyzed enantioselective intramolecular hydroarylation of allylic aryl ethers devoid of a directing group on the aryl group
Kusaka, Satoshi,Ohmura, Toshimichi,Suginome, Michinori
supporting information, p. 13542 - 13545 (2021/12/23)
Although intramolecular hydroarylation is an attractive transformation of allylic aryl ethers, it has suffered from narrow substrate scope. We herein describe Ir/(S)-DTBM-SEGPHOS-catalyzed intramolecular hydroarylation of allylic aryl ethers. The reaction
t-BuOK promoted stereoselective isomerization of allyl aryl ethers
Shi, Mingqi,Wang, Liang,Chen, Qun,He, Mingyang,Shen, Minggui,Zhang, Zhi-hui
, (2020/08/06)
The t-BuOK promoted stereoselective isomerization of allyl aryl ethers has been developed. The reactions proceeded well in methyl tert-butyl ether (MTBE), providing the corresponding products in good to excellent yields (83–96percent). Most of the substra
Development of unique dianionic Ir(III) CCC pincer complexes with a favourable spirocyclic NHC framework
Yan, Zhi-Bo,Dai, Kun-Long,Yang, Bin-Miao,Li, Zi-Hao,Tu, Yong-Qiang,Zhang, Fu-Min,Zhang, Xiao-Ming,Peng, Meng,Chen, Qi-Long,Jing, Ze-Ran
, p. 1761 - 1766 (2020/10/29)
A new type of dianionic Ir(III) CCC pincer complexes (SNHC-Ir, 1a-1c) is successfully designed and synthesized by developing a one-step methodology, which involves an initial coordination of Ir(I) with the NHC and subsequent metallation of double sp2C- H bonds. This method is considerably useful over those reported by using strong coordination ligand or carbonic anion exchange, and would provide an alternative efficient template of organometallics synthesis. Experimental and density functional theory (DFT) calculation results indicate that the spirocyclic framework is a favourable factor for the facile formation and stabilization of these complexes. Primary investigation shows that chloride 1b can well catalyze homo and hetero addition of styrene derivatives and remote olefin isomerization, which represents the first catalytic application of the dianionic CCC pincer complexes.
Potent Reductants via Electron-Primed Photoredox Catalysis: Unlocking Aryl Chlorides for Radical Coupling
Chernowsky, Colleen P.,Cowper, Nicholas G. W.,Wickens, Zachary K.,Williams, Oliver P.
supporting information, (2020/02/04)
We describe a new catalytic strategy to transcend the energetic limitations of visible light by electrochemically priming a photocatalyst prior to excitation. This new catalytic system is able to productively engage aryl chlorides with reduction potentials hundreds of millivolts beyond the potential of Na0 in productive radical coupling reactions. The aryl radicals produced via this strategy can be leveraged for both carbon-carbon and carbon-heteroatom bond-forming reactions. Through direct comparison, we illustrate the reactivity and selectivity advantages of this approach relative to electrolysis and photoredox catalysis.
Lewis acid promoted double bond migration in O-allyl to Z-products by Ru-H complexes
Wang, Haibin,Liu, Shaodong,Sun, Tingting,Lv, Zhanao,Zhan, Zhen,Yin, Guochuan,Chen, Zhuqi
, p. 10 - 17 (2019/03/11)
In catalytic double bond migration reaction, E-configuration olefins were normally generated as the dominant product because E-configuration was thermodynamically favored. However, Z-configuration products are sometimes desired in pharmaceutical chemistry owing to the structure-activity relationship. In this paper, we have demonstrated a new strategy that Lewis acid promoted an widely employed and convenient ruthenium(II) complex for the catalytic isomerization of O-allylethers, leading to thermodynamic-unfavored Z-product under mild conditions. The model substrate of allyl phenyl ether can be simply scaled up to 20 mmol to produce Z-product with TON of 2453 and TOF of 13,430 h?1 at 40–60 °C. The system of Ru(II)/Lewis Acid catalysts was suitable for various substituted O-allylethers and other types of substrates. Through mechanism study including kinetic study, ligand inhibition effect and molecular spectroscopy, the dissociation of PPh3 ligand by the addition of Lewis acid, and the formation a five-membered Ru complex from anchimeric assistance were both recognized as essential steps to improve the reactivity and to control the stereoselectivity of catalytic double bond migration reaction through metal hydride addition-elimination mechanism. This new strategy may provide a new opportunity to produce thermodynamic-unfavored product in heterocyclic compounds for pharmaceutical chemistry.
Hydrosilylation of Allyl Ethers in the Presence of Supported Sulfur-Containing Platinum(II) Complexes
de Vekki,Il’ina,Skvortsov
, p. 25 - 35 (2018/03/09)
Hydrosilylation of allyl ethyl, allyl butyl, allyl glycidyl, allyl benzyl, and allyl phenyl ethers by 1,1,3,3-tetramethyldisiloxane in the presence of supported sulfur-containing platinum(II) complexes with the general formula [{SiO2}O2S/
Palladium-catalysed alkene chain-running isomerization
Kocen, Andrew L.,Brookhart, Maurice,Daugulis, Olafs
supporting information, p. 10010 - 10013 (2017/09/12)
We report a method for palladium-catalysed chain-running isomerization of terminal and internal alkenes. Using an air-stable 2,9-dimethylphenanthroline-palladium catalyst in combination with NaBAr4 promoter, olefins are converted to the most stable double bond isomer at -30 to 20 °C. Silyl enol ethers are readily formed from silylated allylic alcohols. Fluorinated substituents are compatible with the reaction conditions, allowing the synthesis of fluoroenolates. Catalyst loading as low as 0.05% can be employed on a gram scale.
Nitrogen-Doped Carbon-Encapsulated Nickel/Cobalt Nanoparticle Catalysts for Olefin Migration in Allylarenes
Kramer, S?ren,Mielby, Jerrik,Buss, Kasper,Kasama, Takeshi,Kegn?s, S?ren
, p. 2930 - 2934 (2017/08/14)
Olefin migration in allylarenes is typically performed with precious-metal-based homogeneous catalysts. In contrast, very limited progress has been made with the use of cheap, Earth-abundant base metals as heterogeneous catalysts for these transformations—in spite of the obvious economic and environmental advantages. Herein, we report on the use of an easily prepared heterogeneous catalyst material for the migration of olefins, in particular, for allylarenes. The catalyst material consists of nickel/cobalt alloy nanoparticles encapsulated in nitrogen-doped carbon shells. The encapsulated nanoparticles are stable in air and are easily collected by centrifugation, filtration, or magnetic separation. Furthermore, we demonstrate that the catalysts can be reused several times and provide continuously high yields of the olefin-migration product.
An alternative mechanism for the cobalt-catalyzed isomerization of terminal alkenes to (Z)-2-alkenes
Schmidt, Anastasia,N??dling, Alexander R.,Hilt, Gerhard
supporting information, p. 801 - 804 (2015/03/04)
The cobalt-catalyzed selective isomerization of terminal alkenes to the thermodynamically less-stable (Z)-2-alkenes at ambient temperatures takes place by a new mechanism involving the transfer of a hydrogen atom from a Ph2PH ligand to the starting material and the formation of a phosphenium complex, which recycles the Ph2PH complex through a 1,2-H shift.
Mechanistic studies of alkene isomerization catalyzed by CCC-pincer complexes of iridium
Knapp, Spring Melody M.,Shaner, Sarah E.,Kim, Daniel,Shopov, Dimitar Y.,Tendler, Jennifer A.,Pudalov, David M.,Chianese, Anthony R.
supporting information, p. 473 - 484 (2014/02/14)
Iridium complexes containing CCC-pincer m-phenylene-bridged N-heterocyclic carbene ligands were examined as catalysts for alkene isomerization. Complexes containing either mesityl or adamantyl side groups were found to catalyze the isomerization of a number of alkenes to the internal isomers, including 1-octene, vinylcyclohexane, and allylbenzene. Mechanistic studies indicate a surprising dichotomy, apparently caused by ligand steric effects. For the mesityl-substituted catalyst, several lines of evidence provide strong support for isomerization via an iridium allyl hydride intermediate: (1) H-D crossover experiments indicate that 1,3-hydrogen migration is exclusively intramolecular, (2) the catalyst resting state, a π-allyl hydride species, was isolated and serves as a kinetically competent catalyst, (3) NMR experiments indicate that the π-allyl hydride resting state undergoes reversible C-H reductive elimination that is rapid relative to catalytic turnover, and (4) kinetic studies indicate that the isomerization reaction is first order in substrate and catalyst, consistent with turnover-limiting ligand substitution. H-D crossover experiments for alkene isomerization catalyzed by the adamantyl-substituted complex show selectivity for a 1,3-deuterium shift, as well as the intermolecular transfer of hydrogen. These results are consistent with an insertion/elimination mechanism proceeding selectively through a secondary metal-alkyl or with a π-allyl-type mechanism with an unknown pathway for intermolecular hydrogen crossover.
