- Photocatalytic function of the B12 complex with the cyclometalated iridium(III) complex as a photosensitizer under visible light irradiation
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A visible light induced three-component catalytic system with the cobalamin derivative (B12) as a catalyst, the cyclometalated iridium(iii) complex (Irdfppy, Irppy, Irpbt and [Ir{dF(CF3)ppy}2(dtbpy)]PF6) as a photosensitizer and triethanolamine as an electron source under N2 was developed. This catalytic system showed a much higher catalytic efficiency than the previous catalytic system using [Ru(ii)(bpy)3]Cl2 as the photosensitizer for the dechlorination reaction of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT). Noteworthy is the fact that the remarkable high turnover number (over ten thousand) based on B12, which ranks at the top among the reported studies, was obtained when Irdfppy was used as a photosensitizer. This photocatalytic system was also successfully applied to the B12 enzyme-mimic reaction, i.e., the 1,2-migration of the phenyl group of 2-bromomethyl-2-phenylmalonate. The plausible reaction mechanism was proposed, which involved two quenching pathways, an oxidative quenching pathway and a reductive quenching pathway, to be responsible for the initial electron transfer of the excited-state photosensitizers during the DDT dechlorination reaction. Transient photoluminescence experiments revealed that the oxidative quenching of the photosensitizer dominated over the reductive quenching pathway.
- Tian, Hui,Shimakoshi, Hisashi,Park, Gyurim,Kim, Sinheui,You, Youngmin,Hisaeda, Yoshio
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Read Online
- Aerobic Electrochemical Transformations of DDT to Oxygen-Incorporated Products Catalyzed by a B12 Derivative
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Electrochemical transformations of DDT into oxygen-incorporated products, amides and esters, catalyzed by a B12 derivative, heptamethyl cobyrinate perchlorate, have been developed under aerobic conditions. The dechlorinative oxygenation of DDT forms the acyl chloride as an intermediate for the synthesis of the amide and ester in the reaction with the amine and alcohol, respectively. This electrochemical method demonstrated with 20 oxygen-incorporated dechlorinated products up to 88% yields with 15 new compounds and was also successfully applied to the conversion of methoxychlor to an amide and ester.
- Hisaeda, Yoshio,Moniruzzaman, Mohammad,Ono, Toshikazu,Shimakoshi, Hisashi,Yano, Yoshio
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supporting information
p. 2784 - 2791
(2022/01/19)
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- Photoredox Catalytic Phosphite-Mediated Deoxygenation of α-Diketones Enables Wolff Rearrangement and Staudinger Synthesis of β-Lactams
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A novel visible-light-driven catalytic activation of C=O bonds by exploiting the photoredox chemistry of 1,3,2-dioxaphospholes, readily accessible from α-diketones and trialkyl phosphites, is reported. This mild and environmentally friendly strategy provides an unprecedented and efficient access to the Wolff rearrangement reaction which traditionally entails α-diazoketones as precursors. The resulting ketenes could be precisely trapped by alcohols/thiols to give α-aryl (thio)acetates and by imines to afford the valuable β-lactams in up to 99 % yields.
- Jiang, Zhiyong,Li, Haijun,Wei, Guo,Yang, Hui
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supporting information
p. 19696 - 19700
(2021/08/03)
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- Diaryl acetate compound and preparation method thereof
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The invention provides a diaryl acetate compound and a preparation method, and the preparation method comprises the following steps: (1) adding a diary 1, 2-diketone compound, an alcohol compound, trialkyl phosphite and a photocatalyst into a reaction vessel, adding a solvent, and dissolving to obtain a reaction solution; (2) irradiating an reaction liquid by using a light source and stirring until the reaction is complete; and (3) after the reaction is finished, recovering the solvent under reduced pressure and purifying by column chromatography to obtain the diaryl acetate compound. Startingfrom easily available diaryl 1, 2-diketone, the method has the advantages of mild and green reaction conditions, no need of precious transition metal catalysis, economical performance, environmentalprotection, and high practicality.
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Paragraph 0025-0027
(2020/04/29)
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- Palladium-Catalyzed C-H Functionalization of Acyldiazomethane and Tandem Cross-Coupling Reactions
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Palladium-catalyzed C-H functionalization of acyldiazomethanes with aryl iodides has been developed. This reaction is featured by the retention of the diazo functionality in the transformation, thus constituting a novel method for the introduction of diazo functionality to organic molecules. Consistent with the experimental results, the density functional theory (DFT) calculation indicates that the formation of Pd-carbene species in the catalytic cycle through dinitrogen extrusion from the palladium ethyl diazoacetate (Pd-EDA) complex is less favorable. The reaction instead proceeds through Ag2CO3 assisted deprotonation and subsequently reductive elimination to afford the products with diazo functionality remained. This C-H functionalization transformation can be further combined with the recently evolved palladium-catalyzed cross-coupling reaction of diazo compounds with aryl iodides to develop a tandem coupling process for the synthesis of α,α-diaryl esters. DFT calculation supports the involvement of Pd-carbene as reactive intermediate in the catalytic cycle, which goes through facile carbene migratory insertion with a low energy barrier (3.8 kcal/mol). (Chemical Equation Presented).
- Ye, Fei,Qu, Shuanglin,Zhou, Lei,Peng, Cheng,Wang, Chengpeng,Cheng, Jiajia,Hossain, Mohammad Lokman,Liu, Yizhou,Zhang, Yan,Wang, Zhi-Xiang,Wang, Jianbo
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supporting information
p. 4435 - 4444
(2015/04/14)
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- Synthesis of chiral α-diarylacetic esters by stereospecific 1,2-aryl migration promoted by in situ generated acetals from benzoins
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A simple protocol for the synthesis of α-diarylacetic esters from benzoins is described. In situ generated acetal assists rapid 1,2-aryl migration in a stereospecific manner, paving the way to make enantioenriched α-diarylacetic esters from easily accessi
- Kothapalli, Raveendra Babu,Niddana, Ramana,Balamurugan, Rengarajan
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supporting information
p. 1278 - 1281
(2014/04/03)
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- Palladium/copper-catalyzed Di-α-arylation of acetic acid esters
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A bimetallic palladium/copper catalyst system was found to effectively promote the diarylation of alkyl acetates with aryl halides under unprecedentedly mild conditions. The phenanthroline-copper-phosphine catalyst stabilizes the enolate intermediate to the extent that the deprotonation of esters can be achieved even with the mild base potassium phosphate. The palladium tri-tert-butylphosphine co-catalyst mediates the coupling of the resulting copper enolate with a wide variety of aryl halides with selective formation of the corresponding diarylacetic acid esters. Copyright
- Song, Bingrui,Himmler, Thomas,Goossen, Lukas J.
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supporting information; experimental part
p. 1688 - 1694
(2011/09/14)
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- B12-TiO2 hybrid catalyst for dehalogenation of organic halides
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A cobalamin derivative, cobyrinie acid, was effectively immobilized on TiO2, and the hybrid TiO2 was characterized by UV-vis, XPS, MALDI-TOFMS as well as TEM analysis. The hybrid TiO2 exhibits high reactivity for dehalogenation of various organic halides such as phenethyl bromide, benzyl bromide, and 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) under irradiation with UV light at room temperature. Copyright
- Shimakoshi, Hisashi,Sakumori, Emiko,Kaneko, Kenji,Hisaeda, Yoshio
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scheme or table
p. 468 - 469
(2010/03/04)
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- NAPHTHALENONE COMPOUNDS EXHIBITING PROLYL HYDROXYLASE INHIBITORY ACTIVITY, COMPOSITIONS, AND USES THEREOF
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Compounds of Formula (I) and Formula (II) are useful as inhibitors of HIF prolyl hydroxylases. Compounds of Formula(I) and Formula (II) have the following structures, where the definitions of the variables are provided herein.
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Page/Page column 120
(2008/12/06)
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