1
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Price NJ, Nakamura A, Castagnoli N, Tanko JM. Why Does Monoamine Oxidase (MAO) Catalyze the Oxidation of Some Tetrahydropyridines? Chembiochem 2024:e202400126. [PMID: 38602445 DOI: 10.1002/cbic.202400126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/18/2024] [Indexed: 04/12/2024]
Abstract
Results pertaining to the mechanism of the oxidation of the tertiary amine 1-methyl-4-(1-methyl-1-H-pyrrol-2-yl)-1,2,3,6-tetrahydropyridine (MMTP, a close analog of the Parkinsonism inducing compound MPTP) by 3-methyllumiflavin (3MLF), a chemical model for the FAD cofactor of monoamine oxidase, are reported. MMTP and related compounds are among the few tertiary amines that are monoamine oxidase B (MAO-B) substrates. The MMTP/3MLF reaction is catalytic in the presence of O2 and the results under anaerobic conditions strongly suggest the involvement of radical intermediates, consistent with a single electron transfer mechanism. These observations support a new hypothesis to explain the MAO-catalyzed oxidations of amines. In general, electron transfer is thermodynamically unfavorable, and as a result, most 1° and 2° amines react via one of the currently accepted polar pathways. Steric constraints prevent 3° amines from reacting via a polar pathway. Those select 3° amines that are MAO substrates possess certain structural features (e. g., a C-H bond that is α- both to nitrogen and a C=C) that dramatically lower the pKa of the corresponding radical cation. Consequently, the thermodynamically unfavorable electron transfer equilibrium is driven towards products by an extremely favorable deprotonation step in the context of Le Chatelier's principle.
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Affiliation(s)
- Nathan J Price
- Department of Chemistry, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Akiko Nakamura
- Department of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA
| | - Neal Castagnoli
- Department of Chemistry, Virginia Tech, Blacksburg, VA, 24061, USA
| | - James M Tanko
- Department of Chemistry, Virginia Tech, Blacksburg, VA, 24061, USA
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2
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Sil S, Krishnapriya AU, Mandal P, Kuniyil R, Mandal SK. Cross-Coupling Between Aryl Halides and Aryl Alkynes Catalyzed by an Odd Alternant Hydrocarbon. Chemistry 2024:e202400895. [PMID: 38584581 DOI: 10.1002/chem.202400895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/05/2024] [Accepted: 04/06/2024] [Indexed: 04/09/2024]
Abstract
Catalytic cross-coupling between aryl halides and alkynes is considered an extremely important organic transformation (popularly known as the Sonogashira coupling) and it requires a transition metal-based catalyst. Accomplishing such transformation without any transition metal-based catalyst in the absence of any external stimuli such as heat, photoexcitation or cathodic current is highly challenging. This work reports transition-metal-free cross-coupling between aryl halides and alkynes synthesizing a rich library of internal alkynes without any external stimuli. A chemically double-reduced phenalenyl (PLY)-based molecule with the super-reducing property was employed for single electron transfer to activate aryl halides generating reactive aryl radicals, which subsequently react with alkyne. This protocol covers not only various types of aryl, heteroaryl and polyaryl halides but also applies to a large variety of aromatic alkynes at room temperature. With a versatile substrate scope successfully tested on more than 75 entries, this radical-mediated pathway has been explained by several control experiments. All the key reactive intermediates have been characterized with spectroscopic evidence. Detailed DFT calculations have been instrumental in portraying the mechanistic pathway. Furthermore, we have successfully extended this transition-metal-free catalytic strategy for the first time towards solvent-free cross-coupling between solid aryl halide and alkyne substrates.
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Affiliation(s)
- Swagata Sil
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, 741246, West Bengal, India
| | | | - Pallabi Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, 741246, West Bengal, India
| | - Rositha Kuniyil
- Department of Chemistry, Indian Institute of Technology, Palakkad, Palakkad, 678557, Kerala, India
| | - Swadhin K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, 741246, West Bengal, India
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3
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Liu C, Zhang Z, Zhao LL, Bertrand G, Yan X. Mesoionic Carbene-Catalyzed Formyl Alkylation of Aldehydes. Angew Chem Int Ed Engl 2023:e202303478. [PMID: 37070460 DOI: 10.1002/anie.202303478] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/16/2023] [Accepted: 04/17/2023] [Indexed: 04/19/2023]
Abstract
Ketones are among the most useful functional groups in organic synthesis, and they are commonly encountered in a broad range of compounds with various applications. Herein, we describe the mesoionic carbene-catalyzed coupling reaction of aldehydes with non-activated secondary and even primary alkyl halides. This metal-free method utilizes deprotonated Breslow intermediates derived from mesoionic carbenes (MICs), which act as super electron donors and induce the single-electron reduction of alkyl halides. This mild coupling reaction has a broad substrate scope and tolerates many functional groups, which allows to prepare a diversity of simple ketones as well as bio-active molecules by late-stage functionalization.
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Affiliation(s)
- Chang Liu
- Renmin University of China, Chemistry, CHINA
| | | | | | - Guy Bertrand
- UCSD: University of California San Diego, Chemistry and Biochemistry, UNITED STATES
| | - Xiaoyu Yan
- Renmin University of China, Department of Chemistry, Renmin University of China, Beijing 100872, China, 100872, Beijing, CHINA
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4
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Chang F, Fedorov A. Production of Benzene by the Hydrodemethylation of Toluene with Carbon-Supported Potassium Hydride. ChemSusChem 2023; 16:e202202029. [PMID: 36445808 PMCID: PMC10107743 DOI: 10.1002/cssc.202202029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 11/28/2022] [Indexed: 06/16/2023]
Abstract
The hydrodemethylation (HDM) of toluene to benzene is an industrial process performed at elevated temperatures (≈500 °C and higher). Here, it was reported that heating graphite-supported potassium hydride (KH/C) with toluene under H2 atmosphere provided benzene already at 125-250 °C. Depending on the H2 pressure, the reaction was either substoichiometric ( ≤11 bar) or catalytic ( ≥50 bar) with respect to KH, indicating that KH may serve as a radical chain initiator. At 250 °C, the selectivity to benzene was 98 and 63 % when using 6 and 80 bar of H2 , respectively, owing to the competing formation of cyclohexane and methylcyclohexane at high H2 pressure. The used KH/C material was amenable to recycling without a notable loss in the yield of benzene.
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Affiliation(s)
- Fei Chang
- Laboratory of Energy Science and EngineeringDepartment of Mechanical and Process EngineeringETH Zürich8092ZürichSwitzerland
| | - Alexey Fedorov
- Laboratory of Energy Science and EngineeringDepartment of Mechanical and Process EngineeringETH Zürich8092ZürichSwitzerland
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5
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Zhao Y, Zhu H, Sung S, Wink DJ, Zadrozny JM, Driver TG. Counterion Control of t-BuO-Mediated Single Electron Transfer to Nitrostilbenes to Construct N-Hydroxyindoles or Oxindoles. Angew Chem Int Ed Engl 2021; 60:19207-19213. [PMID: 34129257 PMCID: PMC8380450 DOI: 10.1002/anie.202104319] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Indexed: 12/15/2022]
Abstract
tert-Butoxide unlocks new reactivity patterns embedded in nitroarenes. Exposure of nitrostilbenes to sodium tert-butoxide was found to produce N-hydroxyindoles at room temperature without an additive. Changing the counterion to potassium changed the reaction outcome to yield solely oxindoles through an unprecedented dioxygen-transfer reaction followed by a 1,2-phenyl migration. Mechanistic experiments established that these reactions proceed via radical intermediates and suggest that counterion coordination controls whether an oxindole or N-hydroxyindole product is formed.
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Affiliation(s)
- Yingwei Zhao
- Department of Chemistry, University of Illinois at Chicago, 845 W Taylor St. MC 111, Chicago, IL, 60607, USA
- College of Chemical Engineering, Huaqiao University, Xiamen, 668 Jimei Boulevard, Xiamen, Fujian, 361021, P. R. China
| | - Haoran Zhu
- Department of Chemistry, University of Illinois at Chicago, 845 W Taylor St. MC 111, Chicago, IL, 60607, USA
| | - Siyoung Sung
- Department of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA
| | - Donald J Wink
- Department of Chemistry, University of Illinois at Chicago, 845 W Taylor St. MC 111, Chicago, IL, 60607, USA
| | - Joseph M Zadrozny
- Department of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA
| | - Tom G Driver
- Department of Chemistry, University of Illinois at Chicago, 845 W Taylor St. MC 111, Chicago, IL, 60607, USA
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6
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Zhu C, Yue H, Jia J, Rueping M. Nickel-Catalyzed C-Heteroatom Cross-Coupling Reactions under Mild Conditions via Facilitated Reductive Elimination. Angew Chem Int Ed Engl 2021; 60:17810-17831. [PMID: 33252192 DOI: 10.1002/anie.202013852] [Citation(s) in RCA: 97] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Indexed: 12/16/2022]
Abstract
The formation of C-heteroatom bonds represents an important type of bond-forming reaction in organic synthesis and often provides a fast and efficient access to privileged structures found in pharmaceuticals, agrochemical and materials. In contrast to conventional Pd- or Cu-catalyzed C-heteroatom cross-couplings under high-temperature conditions, recent advances in homo- and heterogeneous Ni-catalyzed C-heteroatom formations under mild conditions are particularly attractive from the standpoint of sustainability and practicability. The generation of NiIII and excited NiII intermediates facilitate the reductive elimination step to achieve mild cross-couplings. This review provides an overview of the state-of-the-art approaches for mild C-heteroatom bond formations and highlights the developments in photoredox and nickel dual catalysis involving SET and energy transfer processes; photoexcited nickel catalysis; electro and nickel dual catalysis; heterogeneous photoredox and nickel dual catalysis involving graphitic carbon nitride (mpg-CN), metal organic frameworks (MOFs) or semiconductor quantum dots (QDs); as well as more conventional zinc and nickel dual catalyzed reactions.
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Affiliation(s)
- Chen Zhu
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Huifeng Yue
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Jiaqi Jia
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Magnus Rueping
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
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Yu M, Liu Y. A QM/MM Study on the Initiation Reaction of Firefly Bioluminescence-Enzymatic Oxidation of Luciferin. Molecules 2021; 26:4222. [PMID: 34299498 DOI: 10.3390/molecules26144222] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/09/2021] [Accepted: 07/10/2021] [Indexed: 11/17/2022] Open
Abstract
Among all bioluminescent organisms, the firefly is the most famous, with a high luminescent efficiency of 41%, which is widely used in the fields of biotechnology, biomedicine and so on. The entire bioluminescence (BL) process involves a series of complicated in-vivo chemical reactions. The BL is initiated by the enzymatic oxidation of luciferin (LH2). However, the mechanism of the efficient spin-forbidden oxygenation is far from being totally understood. Via MD simulation and QM/MM calculations, this article describes the complete process of oxygenation in real protein. The oxygenation of luciferin is initiated by a single electron transfer from the trivalent anionic LH2 (L3-) to O2 to form 1[L•2-…O2•-]; the entire reaction is carried out along the ground-state potential energy surface to produce the dioxetanone (FDO-) via three transition states and two intermediates. The low energy barriers of the oxygenation reaction and biradical annihilation involved in the reaction explain this spin-forbidden reaction with high efficiency. This study is helpful for understanding the BL initiation of fireflies and the other oxygen-dependent bioluminescent organisms.
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8
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Li J, Lear MJ, Hayashi Y. Direct Cyclopropanation of α-Cyano β-Aryl Alkanes by Light-Mediated Single Electron Transfer Between Donor-Acceptor Pairs. Chemistry 2021; 27:5901-5905. [PMID: 33565170 DOI: 10.1002/chem.202100341] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/08/2021] [Indexed: 12/21/2022]
Abstract
Cyclopropanes are traditionally prepared by the formal [2+1] addition of carbene or radical based C1 units to alkenes. In contrast, the one-pot intermolecular cyclopropanation of alkanes by redox active C1 units has remained unrealised. Herein, we achieved this process simply by exposing β-aryl propionitriles and C1 radical precursors (N-oxy esters) to base and blue light. The overall process is redox-neutral and a photocatalyst, whether metal- or organic-based, is not required. Our findings support that single electron transfer (SET) from the α-cyano carbanion of the propionitrile to the N-oxy ester is facilitated by blue-light via their electron donor-acceptor (EDA) complex. The α-cyano carbon radical thus formed can then lose a β-proton to form a π-resonance stabilised radical anion that preferentially couples at the benzylic β-position with a decarboxylated C1 radical unit. This new transition metal-free chemistry tolerates both electron rich and electron deficient (hetero)aryl systems, even sulfide or alkene functionality, to afford a range of cis-aryl/cyano cyclopropanes bearing congested tetrasubstituted quaternary carbons.
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Affiliation(s)
- Jing Li
- Department of Chemistry, Graduate School of Science, Tohoku University, Aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan
| | - Martin J Lear
- School of Chemistry, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
| | - Yujiro Hayashi
- Department of Chemistry, Graduate School of Science, Tohoku University, Aza-Aoba, Aoba-ku, Sendai, 980-8578, Japan
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9
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Abstract
In the field of synthetic organic chemistry, photochemical and electrochemical approaches are often considered to be competing technologies that induce single electron transfer (SET). Recently, their fusion, i. e., the "photoelectrochemical" approach, has become the focus of attention. In this approach, both solar and electrical energy are used in creative combinations. Historically, the term "photoelectrochemistry" has been used in more inorganic fields, where a photovoltaic effect exhibited by semiconducting materials is employed. Semiconductors have also been studied intensively as photocatalysts; however, they recently have taken a back seat to molecular photocatalysts. In this account, we would like to revisit semiconductor photocatalysts in the field of synthetic organic chemistry to demonstrate that semiconductor "photoelectrochemical" approaches are more than mere alternatives to molecular photochemical and/or electrochemical approaches.
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Affiliation(s)
- Yohei Okada
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
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10
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Yao H, Hu W, Zhang W. Difunctionalization of Alkenes and Alkynes via Intermolecular Radical and Nucleophilic Additions. Molecules 2020; 26:E105. [PMID: 33379397 DOI: 10.3390/molecules26010105] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/24/2020] [Accepted: 12/24/2020] [Indexed: 12/31/2022]
Abstract
Popular and readily available alkenes and alkynes are good substrates for the preparation of functionalized molecules through radical and/or ionic addition reactions. Difunctionalization is a topic of current interest due to its high efficiency, substrate versatility, and operational simplicity. Presented in this article are radical addition followed by oxidation and nucleophilic addition reactions for difunctionalization of alkenes or alkynes. The difunctionalization could be accomplished through 1,2-addition (vicinal) and 1,n-addition (distal or remote) if H-atom or group-transfer is involved in the reaction process. A wide range of moieties, such as alkyl (R), perfluoroalkyl (Rf), aryl (Ar), hydroxy (OH), alkoxy (OR), acetatic (O2CR), halogenic (X), amino (NR2), azido (N3), cyano (CN), as well as sulfur- and phosphorous-containing groups can be incorporated through the difunctionalization reactions. Radicals generated from peroxides or single electron transfer (SET) agents, under photoredox or electrochemical reactions are employed for the reactions.
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Abstract
The plant kingdom is a rich source of health-promoting compounds and has always played a fundamental role in the isolation, identification, and modification of compounds able to perform several properties on live organisms. Among them, the so-called “antioxidants” have a major potentiality to increase human wellness. Antioxidants are important components in the signaling and defense mechanisms in some plants, where they are precursors of compounds of greater complexity, the modulator of plant growth, and the defensive system against pathogenic organisms and predators. The extraordinary variety of chemical structure and substitution present in the different plant antioxidants make them an inestimable source of interesting compounds, with the ability to counter reactive oxygen/nitrogen species (ROS/RNS) and to stimulate the activation of signal cascade inside the cells. The mechanisms by which antioxidants detoxify these dangerous compounds are complex and involve either direct or indirect interaction with radicals. Antioxidants inhibit or quench free radical reactions mainly based on their reducing capacity or hydrogen atom-donating capacity, their solubility, and chelating properties. Moreover, their ability to modulate key metabolic enzymes and activate/block gene transcription also has remarkable importance.
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12
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Murali A, Sampath S, Appukutti Achuthan B, Sakar M, Chandrasekaran S, Suthanthira Vanitha N, Joseph Bensingh R, Abdul Kader M, Jaisankar SN. Copper (0) Mediated Single Electron Transfer-Living Radical Polymerization of Methyl Methacrylate: Functionalized Graphene as a Convenient Tool for Radical Initiator. Polymers (Basel) 2020; 12:E874. [PMID: 32290159 PMCID: PMC7240427 DOI: 10.3390/polym12040874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/11/2020] [Accepted: 03/18/2020] [Indexed: 01/27/2023] Open
Abstract
Polymer nanocomposites have been synthesized by the covalent addition of bromide-functionalized graphene (Graphene-Br) through the single electron transfer-living radical polymerization technique (SET-LRP). Graphite functionalized with bromide for the first time via an efficient route using mild reagents has been designed to develop a graphene based radical initiator. The efficiency of sacrificial initiator (ethyl α-bromoisobutyrate) has also been compared with a graphene based initiator towards monitoring their Cu(0) mediated controlled molecular weight and morphological structures through mass spectroscopy (MOLDI-TOF) and field emission scanning electron microscopy (FE-SEM) analysis, respectively. The enhancement in thermal stability is observed for graphene-grafted-poly(methyl methacrylate) (G-g-PMMA) at 392 °C, which may be due to the influence ofthe covalent addition of graphene, whereas the sacrificial initiator used to synthesize G-graft-PMMA (S) has low thermal stability as analyzed by TGA. A significant difference is noticed on their glass transition and melting temperatures by DSC. The controlled formation and structural features of the polymer-functionalized-graphene is characterized by Raman, FT-IR, UV-Vis spectroscopy, NMR, and zeta potential measurements. The wettability measurements of the novel G-graft-PMMA on leather surface were found to be better in hydrophobic nature with a water contact angle of 109 ± 1°.
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Affiliation(s)
- Adhigan Murali
- School for Advanced Research in Polymers (SARP)-Advanced Research School for Technology and Product Simulation (ARSTPS), Central Institute of Plastics Engineering & Technology (CIPET), Ministry of Chemicals & Fertilizers, Govt. of India, Chennai 600032, India; (R.J.B.); (M.A.K.)
| | - Srinivasan Sampath
- Department of Materials Science, School of Technology, Central University of Tamil Nadu, Thiruvarur 610101, India;
| | - Boopathi Appukutti Achuthan
- Polymer Science and Technology Division, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Adyar, Chennai 600020, India; (B.A.A.); (S.N.J.)
| | - Mohan Sakar
- Centre for Nano and Material Sciences, Jain University, Bangalore 562112, Karnataka, India
| | | | - N. Suthanthira Vanitha
- Department of Electrical & Electronics Engineering, Muthayammal Engineering College (Autonomous), Namakkal 637408, Tamilnadu, India;
| | - R. Joseph Bensingh
- School for Advanced Research in Polymers (SARP)-Advanced Research School for Technology and Product Simulation (ARSTPS), Central Institute of Plastics Engineering & Technology (CIPET), Ministry of Chemicals & Fertilizers, Govt. of India, Chennai 600032, India; (R.J.B.); (M.A.K.)
| | - M. Abdul Kader
- School for Advanced Research in Polymers (SARP)-Advanced Research School for Technology and Product Simulation (ARSTPS), Central Institute of Plastics Engineering & Technology (CIPET), Ministry of Chemicals & Fertilizers, Govt. of India, Chennai 600032, India; (R.J.B.); (M.A.K.)
| | - Sellamuthu N. Jaisankar
- Polymer Science and Technology Division, Council of Scientific and Industrial Research (CSIR)-Central Leather Research Institute (CLRI), Adyar, Chennai 600020, India; (B.A.A.); (S.N.J.)
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Hu Y, Solé-Daura A, Yao YR, Liu X, Liu S, Yu A, Peng P, Poblet JM, Rodríguez-Fortea A, Echegoyen L, Li FF. Chemical Reactions of Cationic Metallofullerenes: An Alternative Route for Exohedral Functionalization. Chemistry 2020; 26:1748-1753. [PMID: 31749187 DOI: 10.1002/chem.201904854] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 11/18/2019] [Indexed: 11/10/2022]
Abstract
The chemistry of cationic forms of clusterfullerenes remain less explored than that of the corresponding neutral or anionic species. In the present work, M3 N@Ih -C80 (M=Sc or Lu) cations were generated by both electrochemical and chemical oxidation methods. The as-obtained cations successfully underwent the typical Bingel-Hirsch reaction that fails with neutral Sc3 N@Ih -C80 . Two isomeric Sc3 N@Ih -C80 cation derivatives, [5,6]-open and [6,6]-open adducts, were synthesized, and the former has never been prepared by means of a Bingel-Hirsch reaction with neutral clusterfullerenes. In the case of the Lu3 N@Ih -C80 cation, however, only a [6,6]-open adduct was obtained. Density functional theory (DFT) calculations indicated that the oxidized M3 N@Ih -C80 was much more reactive than the neutral compound upon addition of the diethyl bromomalonate anion. The Bingel-Hirsch reaction of M3 N@Ih -C80 cations occurred by means of an unusual outer-sphere single-electron transfer (SET) process from the diethyl bromomalonate anion to the stable intermediate [M3 N@C80 (C2 H5 COO)2 CBr]. . Remarkably, the diethyl bromomalonate anion was found to act as both a nucleophile and an electron donor.
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Affiliation(s)
- Yajing Hu
- State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of, Science and Technology, Wuhan, 430074, P.R. China
| | - Albert Solé-Daura
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel⋅lí Domingo 1, 43007, Tarragona, Spain
| | - Yang-Rong Yao
- Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, USA
| | - Xuechen Liu
- State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of, Science and Technology, Wuhan, 430074, P.R. China
| | - Sijie Liu
- State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of, Science and Technology, Wuhan, 430074, P.R. China
| | - Ao Yu
- State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of, Science and Technology, Wuhan, 430074, P.R. China
| | - Ping Peng
- State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of, Science and Technology, Wuhan, 430074, P.R. China
| | - Josep M Poblet
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel⋅lí Domingo 1, 43007, Tarragona, Spain
| | - Antonio Rodríguez-Fortea
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel⋅lí Domingo 1, 43007, Tarragona, Spain
| | - Luis Echegoyen
- Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas, 79968, USA
| | - Fang-Fang Li
- State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of, Science and Technology, Wuhan, 430074, P.R. China
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14
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Xia PJ, Song D, Ye ZP, Hu YZ, Xiao JA, Xiang HY, Chen XQ, Yang H. Photoinduced Single-Electron Transfer as an Enabling Principle in the Radical Borylation of Alkenes with NHC-Borane. Angew Chem Int Ed Engl 2020; 59:6706-6710. [PMID: 31849140 DOI: 10.1002/anie.201913398] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 11/28/2019] [Indexed: 11/06/2022]
Abstract
A photoinduced SET process enables the direct B-H bond activation of NHC-boranes. In contrast to common hydrogen atom transfer (HAT) strategies, this photoinduced reaction simply takes advantage of the beneficial redox potentials of NHC-boranes, thus obviating the need for extra radical initiators. The resulting NHC-boryl radical was used for the borylation of a wide range of α-trifluoromethylalkenes and alkenes with diverse electronic and structural features, providing facile access to highly functionalized borylated molecules. Labeling and photoquenching experiments provide insight into the mechanism of this photoinduced SET pathway.
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Affiliation(s)
- Peng-Ju Xia
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Dan Song
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Zhi-Peng Ye
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Yuan-Zhuo Hu
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Jun-An Xiao
- Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning, 530001, Guangxi, P. R. China
| | - Hao-Yue Xiang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China
| | - Xiao-Qing Chen
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China.,Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Central South University, Changsha, 410083, P. R. China
| | - Hua Yang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, P. R. China.,Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Central South University, Changsha, 410083, P. R. China
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15
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16
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Abstract
Neutral organic super electron donors (SEDs) display impressive reducing power but, until now, it has not been possible to use them catalytically in radical chain reactions. This is because, following electron transfer, these donors form persistent radical cations that trap substrate-derived radicals. This paper unlocks a conceptually new approach to super electron donors that overcomes this issue, leading to the first catalytic neutral organic super electron donor.
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Affiliation(s)
- Simon Rohrbach
- Dept. of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK
| | - Rushabh S Shah
- GlaxoSmithKline Medicines Research Centre, Gunnels Wood Road, Stevenage, SG1 2NY, UK
| | - Tell Tuttle
- Dept. of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK
| | - John A Murphy
- Dept. of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK
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17
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Carreon-Gonzalez M, Vivier-Bunge A, Alvarez-Idaboy JR. Thiophenols, Promising Scavengers of Peroxyl Radicals: Mechanisms and kinetics. J Comput Chem 2019; 40:2103-2110. [PMID: 31124582 DOI: 10.1002/jcc.25862] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/13/2019] [Accepted: 05/05/2019] [Indexed: 01/03/2023]
Abstract
The activity of 12 thiophenols as primary antioxidants in aqueous solution has been studied using density functional theory. Twelve different substituted thiophenols were tested as peroxyl radicals scavengers. Single electron transfer (SET) and formal hydrogen transfer (FHT) were investigated. The SET mechanism was found to be the main mechanism, with rate constants that are close to the diffusion limit, which means that these thiophenolic compounds have the capacity to scavenge peroxyl radicals before they can damage biomolecules. All 12 thiophenolic compounds react faster with methylperoxyl than with hydroperoxyl radicals. In addition, it was found that pH plays an important role in the reactivity of these compounds. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Mirzam Carreon-Gonzalez
- Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico
| | - Annik Vivier-Bunge
- Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, 09340, Mexico
| | - Juan Raul Alvarez-Idaboy
- Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, Mexico City, 04510, Mexico
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18
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Jójárt R, Traj P, Kovács É, Horváth Á, Schneider G, Szécsi M, Pál A, Paragi G, Mernyák E. Synthesis, Biological Evaluation and Docking Studies of 13-Epimeric 10-fluoro- and 10-Chloroestra-1,4-dien-3-ones as Potential Aromatase Inhibitors. Molecules 2019; 24:E1783. [PMID: 31072017 PMCID: PMC6540200 DOI: 10.3390/molecules24091783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 02/03/2023] Open
Abstract
Fluorination of 13-epimeric estrones and their 17-deoxy counterparts was performed with Selectfluor as the reagent. In acetonitrile or trifluoroacetic acid (TFA), 10β-fluoroestra-1,4-dien-3-ones were formed exclusively. Mechanistic investigations suggest that fluorinations occurred via SET in acetonitrile, but another mechanism was operative in TFA. Simultaneous application of N-chlorosuccinimide (NCS) and Selectfluor in TFA led to a 1.3:1 mixture of 10β-fluoroestra-1,4-dien-3-one and 10β-chloroestra-1,4-dien-3-one as the main products. The potential inhibitory action of the 10-fluoro- or 10-chloroestra-1,4-dien-3-one products on human aromatase was investigated via in vitro radiosubstrate incubation. The classical estrane conformation with trans ring anellations and a 13β-methyl group seems to be crucial for the inhibition of the enzyme, while test compounds bearing the 13β-methyl group exclusively displayed potent inhibitory action with submicromolar or micromolar IC50 values. Concerning molecular level explanation of biological activity or inactivity, computational simulations were performed. Docking studies reinforced that besides the well-known Met374 H-bond connection, the stereocenter in the 13 position has an important role in the binding affinity. The configuration inversion at C-13 results in weaker binding of 13α-estrone derivatives to the aromatase enzyme.
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Affiliation(s)
- Rebeka Jójárt
- Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary.
| | - Péter Traj
- Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary.
| | - Édua Kovács
- Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary.
| | - Ágnes Horváth
- Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary.
| | - Gyula Schneider
- Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary.
| | - Mihály Szécsi
- 1st Department of Medicine, University of Szeged, Korányi fasor 8⁻10, H-6720 Szeged, Hungary.
| | - Attila Pál
- Department of Medicinal Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary.
| | - Gábor Paragi
- MTA-SZTE Biomimetic Systems Research Group, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary.
- Institute of Physics, University of Pecs, Ifjúság útja 6, H-7624 Pécs, Hungary.
| | - Erzsébet Mernyák
- Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary.
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19
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Angelini L, Davies J, Simonetti M, Malet Sanz L, Sheikh NS, Leonori D. Reaction of Nitrogen-Radicals with Organometallics Under Ni-Catalysis: N-Arylations and Amino-Functionalization Cascades. Angew Chem Int Ed Engl 2019; 58:5003-5007. [PMID: 30779864 PMCID: PMC6519068 DOI: 10.1002/anie.201900510] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 02/18/2019] [Indexed: 11/11/2022]
Abstract
Herein, we report a strategy for the generation of nitrogen-radicals by ground-state single electron transfer with organyl-NiI species. Depending on the philicity of the N-radical, two types of processes have been developed. In the case of nucleophilic aminyl radicals direct N-arylation with aryl organozinc, organoboron, and organosilicon reagents was achieved. In the case of electrophilic amidyl radicals, cascade processes involving intramolecular cyclization, followed by reaction with both aryl and alkyl organometallics have been developed. The N-cyclization-alkylation cascade introduces a novel retrosynthetic disconnection for the assembly of substituted lactams and pyrrolidines with its potential demonstrated in the short total synthesis of four venom alkaloids.
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Affiliation(s)
- Lucrezia Angelini
- School of ChemistryUniversity of ManchesterOxford RoadManchesterM13 9PLUK
| | - Jacob Davies
- School of ChemistryUniversity of ManchesterOxford RoadManchesterM13 9PLUK
| | - Marco Simonetti
- School of ChemistryUniversity of ManchesterOxford RoadManchesterM13 9PLUK
| | - Laia Malet Sanz
- Eli Lilly and Company LimitedErl Wood Manor, WindeleshamSurreyGU20 6PHUK
| | - Nadeem S. Sheikh
- Department of ChemistryCollege of ScienceKing Faisal UniversityP.O. Box 380Al-Ahsa31982Saudi Arabia
| | - Daniele Leonori
- School of ChemistryUniversity of ManchesterOxford RoadManchesterM13 9PLUK
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20
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Shimizu R, Okada Y, Chiba K. Stepwise radical cation Diels-Alder reaction via multiple pathways. Beilstein J Org Chem 2018; 14:704-708. [PMID: 29719568 PMCID: PMC5905251 DOI: 10.3762/bjoc.14.59] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/09/2018] [Indexed: 11/23/2022] Open
Abstract
Herein we disclose the radical cation Diels–Alder reaction of aryl vinyl ethers by electrocatalysis, which is triggered by an oxidative SET process. The reaction clearly proceeds in a stepwise fashion, which is a rare mechanism in this class. We also found that two distinctive pathways, including “direct” and “indirect”, are possible to construct the Diels–Alder adduct.
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Affiliation(s)
- Ryo Shimizu
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
| | - Yohei Okada
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Kazuhiro Chiba
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
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21
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Imada Y, Okada Y, Chiba K. Investigating radical cation chain processes in the electrocatalytic Diels-Alder reaction. Beilstein J Org Chem 2018; 14:642-647. [PMID: 29623126 PMCID: PMC5870144 DOI: 10.3762/bjoc.14.51] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 02/27/2018] [Indexed: 01/09/2023] Open
Abstract
Single electron transfer (SET)-triggered radical ion-based reactions have proven to be powerful options in synthetic organic chemistry. Although unique chain processes have been proposed in various photo- and electrochemical radical ion-based transformations, the turnover number, also referred to as catalytic efficiency, remains unclear in most cases. Herein, we disclose our investigations of radical cation chain processes in the electrocatalytic Diels-Alder reaction, leading to a scalable synthesis. A gram-scale synthesis was achieved with high current efficiency of up to 8000%. The reaction monitoring profiles showed sigmoidal curves with induction periods, suggesting the involvement of intermediate(s) in the rate determining step.
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Affiliation(s)
- Yasushi Imada
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
| | - Yohei Okada
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Kazuhiro Chiba
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
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22
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Jacquet J, Cheaib K, Ren Y, Vezin H, Orio M, Blanchard S, Fensterbank L, Desage-El Murr M. Circumventing Intrinsic Metal Reactivity: Radical Generation with Redox-Active Ligands. Chemistry 2017; 23:15030-15034. [PMID: 28873243 DOI: 10.1002/chem.201704049] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Indexed: 01/09/2023]
Abstract
Nickel complexes have gained sustained attention as efficient catalysts in cross-coupling reactions and co-catalysts in dual systems due to their ability to react with radical species. Central to this reactivity is nickel's propensity to shuttle through several accessible redox states from Ni0 to NiIV . Here, we report the catalytic generation of trifluoromethyl radicals from a nickel complex bearing redox-active iminosemiquinone ligands. This unprecedented reactivity is enabled through ligand-based oxidation performing electron transfer to an electrophilic CF3+ source while the nickel oxidation state is preserved. Additionally, extension of this reactivity to a copper complex bearing a single redox equivalent is reported, thus providing a unified reactivity scheme. These results open new pathways in radical chemistry with redox-active ligands.
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Affiliation(s)
- Jérémy Jacquet
- Sorbonne Universités, UPMC, Université Paris 06, UMR CNRS 8232, Institut Parisien de Chimie Moléculaire, France
| | - Khaled Cheaib
- Sorbonne Universités, UPMC, Université Paris 06, UMR CNRS 8232, Institut Parisien de Chimie Moléculaire, France
| | - Yufeng Ren
- Sorbonne Universités, UPMC, Université Paris 06, UMR CNRS 8232, Institut Parisien de Chimie Moléculaire, France
| | - Hervé Vezin
- Laboratoire de Spectrochimie Infrarouge et Raman, Université des Sciences et Technologies de Lille, UMR CNRS 8516, 59655 Villeneuve d'Ascq Cedex, France
| | - Maylis Orio
- Aix Marseille Université, CNRS, Centrale Marseille iSm2 UMR 7313, 13397, Marseille cedex 20, France
| | - Sébastien Blanchard
- Sorbonne Universités, UPMC, Université Paris 06, UMR CNRS 8232, Institut Parisien de Chimie Moléculaire, France
| | - Louis Fensterbank
- Sorbonne Universités, UPMC, Université Paris 06, UMR CNRS 8232, Institut Parisien de Chimie Moléculaire, France
| | - Marine Desage-El Murr
- Sorbonne Universités, UPMC, Université Paris 06, UMR CNRS 8232, Institut Parisien de Chimie Moléculaire, France.,Institut de Chimie, Université de Strasbourg, 1 rue Blaise Pascal, 67000, Strasbourg, France
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23
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Wang DY, Morimoto K, Yang ZK, Wang C, Uchiyama M. Organozinc-Mediated Direct C-C Bond Formation via C-N Bond Cleavage of Ammonium Salts. Chem Asian J 2017; 12:2554-2557. [PMID: 28834419 DOI: 10.1002/asia.201701132] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 08/21/2017] [Indexed: 11/08/2022]
Abstract
We report a direct cross-coupling reaction between diarylzinc (Ar2 Zn) and aryltrimethylammonium salts (ArNMe3+ ⋅- OTf) in the presence of LiCl, via C-N bond cleavage. The reaction takes place smoothly upon heating in THF without any external catalyst, enabling an efficient and chemoselective formation of biaryl products. Mechanistic studies indicate that the reaction proceeds through a single electron transfer route.
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Affiliation(s)
- Dong-Yu Wang
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to, 113-0033, Japan.,Advanced Elements Chemistry Research Team, RIKEN Center for Sustainable Resource Science, and Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198, Japan.,Current address: CAS Key Laboratory of Receptor Research and the State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Pudong, Shanghai, 201203, China
| | - Koki Morimoto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to, 113-0033, Japan
| | - Ze-Kun Yang
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to, 113-0033, Japan.,Advanced Elements Chemistry Research Team, RIKEN Center for Sustainable Resource Science, and Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198, Japan
| | - Chao Wang
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to, 113-0033, Japan.,Advanced Elements Chemistry Research Team, RIKEN Center for Sustainable Resource Science, and Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198, Japan
| | - Masanobu Uchiyama
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo-to, 113-0033, Japan.,Advanced Elements Chemistry Research Team, RIKEN Center for Sustainable Resource Science, and Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama-ken, 351-0198, Japan
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24
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Rovira M, Roldán-Gómez S, Martin-Diaconescu V, Whiteoak CJ, Company A, Luis JM, Ribas X. Trifluoromethylation of a Well-Defined Square-Planar Aryl-Ni II Complex involving Ni III /CF 3. and Ni IV -CF 3 Intermediate Species. Chemistry 2017; 23:11662-11668. [PMID: 28685908 DOI: 10.1002/chem.201702168] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Indexed: 11/11/2022]
Abstract
Ni-mediated trifluoromethylation of an aryl-Br bond in model macrocyclic ligands (Ln -Br) has been thoroughly studied, starting with an oxidative addition at Ni0 to obtain well-defined aryl-NiII -Br complexes ([Ln -NiII ]Br). Abstraction of the halide with AgX (X=OTf- or ClO4- ) thereafter provides [Ln -NiII ](OTf). The nitrate analogue has been obtained through a direct C-H activation of an aryl-H bond using NiII salts, and this route has been studied by X-ray absorption spectroscopy (XAS). Crystallographic XRD and XAS characterization has shown a tight macrocyclic coordination in the aryl-NiII complex, which may hamper direct reaction with nucleophiles. On the contrary, enhanced reactivity is observed with oxidants, and the reaction of [Ln -NiII ](OTf) with CF3+ sources afforded Ln -CF3 products in quantitative yield. A combined experimental and theoretical mechanistic study provides new insights into the operative mechanism for this transformation. Computational analysis indicates the occurrence of an initial single electron transfer (SET) to 5-(trifluoromethyl)dibenzothiophenium triflate (TDTT), producing a transient L1 -NiIII /CF3. adduct, which rapidly recombines to form a [L1 -NiIV -CF3 ](X)2 intermediate species. A final facile reductive elimination affords L1 -CF3 . The well-defined square-planar model system studied here permits to gain fundamental knowledge on the rich redox chemistry of nickel, which is sought to facilitate the development of new Ni-based trifluoromethylation methodologies.
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Affiliation(s)
- Mireia Rovira
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat Ciències, 17003, Girona, Catalonia, Spain
| | - Steven Roldán-Gómez
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat Ciències, 17003, Girona, Catalonia, Spain
| | - Vlad Martin-Diaconescu
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat Ciències, 17003, Girona, Catalonia, Spain
| | - Christopher J Whiteoak
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat Ciències, 17003, Girona, Catalonia, Spain.,Biomolecular Sciences Research Centre, Faculty of Health and Wellbeing, Sheffield Hallam University, City Campus, Sheffield, S1 1WB, UK
| | - Anna Company
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat Ciències, 17003, Girona, Catalonia, Spain
| | - Josep M Luis
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat Ciències, 17003, Girona, Catalonia, Spain
| | - Xavi Ribas
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat Ciències, 17003, Girona, Catalonia, Spain
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25
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Qu Y, Tateno H, Matsumura Y, Kashiwagi T, Atobe M. Cathodic Aromatic C,C Cross-Coupling Reaction via Single Electron Transfer Pathway. Molecules 2017; 22:molecules22030413. [PMID: 28272364 PMCID: PMC6155275 DOI: 10.3390/molecules22030413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 02/20/2017] [Accepted: 03/02/2017] [Indexed: 12/03/2022] Open
Abstract
We have successfully developed a novel cathodic cross-coupling reaction of aryl halides with arenes. Utilization of the cathodic single electron transfer (SET) mechanism for activation of aryl halides enables the cross-coupling reaction to proceed without the need for any transition metal catalysts or single electron donors in a mild condition. The SET from a cathode to an aryl halide initiates a radical chain by giving an anion radical of the aryl halide. The following propagation cycle also consists entirely of anion radical intermediates.
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Affiliation(s)
- Yang Qu
- Graduate School of Environment and Information Sciences, Yokohama National University, 79-7, Tokiwadai, Hodogaya-ku, Yokohama 240851, Japan.
| | - Hiroyuki Tateno
- Graduate School of Environment and Information Sciences, Yokohama National University, 79-7, Tokiwadai, Hodogaya-ku, Yokohama 240851, Japan.
| | - Yoshimasa Matsumura
- Graduate School of Environment and Information Sciences, Yokohama National University, 79-7, Tokiwadai, Hodogaya-ku, Yokohama 240851, Japan.
| | - Tsuneo Kashiwagi
- Graduate School of Environment and Information Sciences, Yokohama National University, 79-7, Tokiwadai, Hodogaya-ku, Yokohama 240851, Japan.
| | - Mahito Atobe
- Graduate School of Environment and Information Sciences, Yokohama National University, 79-7, Tokiwadai, Hodogaya-ku, Yokohama 240851, Japan.
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26
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Amatov T, Gebauer M, Pohl R, Cisařová I, Jahn U. Oxidative radical cyclizations of diketopiperazines bearing an amidomalonate unit. Heterointermediate reaction sequences toward the asperparalines and stephacidins. Free Radic Res 2016; 50:S6-S17. [PMID: 27806645 DOI: 10.1080/10715762.2016.1223295] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A novel approach to the diazabicyclo[2.2.2]octane core of prenylated bridged diketopiperazine alkaloids is described by direct oxidative cyclizations of functionalized diketopiperazines mediated by ferrocenium hexafluorophosphate or the Mn(OAc)3•2H2O/Cu(OTf)2 system. Divergent reaction pathways take place depending on the substitution pattern of the substrates and the oxidation conditions such as temperature or the presence or absence of persistent radical TEMPO. For ester-substituted diketopiperazines, the ester group exerts a significant influence on the reaction outcome and stereochemistry of the radical cyclizations.
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Affiliation(s)
- Tynchtyk Amatov
- a Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , Flemingovo namesti 2 , Prague 6, Czech Republic
| | - Martin Gebauer
- a Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , Flemingovo namesti 2 , Prague 6, Czech Republic
| | - Radek Pohl
- a Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , Flemingovo namesti 2 , Prague 6, Czech Republic
| | - Ivana Cisařová
- b Department of Inorganic Chemistry, Faculty of Science , Charles University in Prague , Hlavova 2030/8 , Prague 2, Czech Republic
| | - Ullrich Jahn
- a Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , Flemingovo namesti 2 , Prague 6, Czech Republic
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27
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Giuglio-Tonolo AG, Terme T, Vanelle P. Original Synthesis of Fluorenyl Alcohol Derivatives by Reductive Dehalogenation Initiated by TDAE. Molecules 2016; 21:E1408. [PMID: 27783046 DOI: 10.3390/molecules21101408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/18/2016] [Accepted: 10/19/2016] [Indexed: 11/17/2022] Open
Abstract
We report here a novel and easy-to-handle reductive dehalogenation of 9-bromofluorene in the presence of arylaldehydes and dicarbonyl derivatives to give the corresponding fluorenyl alcohol derivatives and Darzens epoxides as by-products in tetrakis(dimethylamino)ethylene (TDAE) reaction conditions. The reaction is believed to proceed via two successive single electron transfers to generate the fluorenyl anion which was able to react with different electrophiles. A mechanistic study was conducted to understand the formation of the epoxide derivatives.
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28
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Kareem HS, Nordin N, Heidelberg T, Abdul-Aziz A, Ariffin A. Conjugated Oligo-Aromatic Compounds Bearing a 3,4,5-Trimethoxy Moiety: Investigation of Their Antioxidant Activity Correlated with a DFT Study. Molecules 2016; 21:E224. [PMID: 26901175 DOI: 10.3390/molecules21020224] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 12/14/2022] Open
Abstract
A series of heterocyclic compounds bearing the well-known free radical scavenging 3,4,5-trimethoxybenzyloxy group, was synthesized. The key compound 4-(3,4,5-trimethoxybenzyl-oxy)benzohydrazide was converted into thiosemicarbazide derivatives, which were subsequently cyclized with NaOH to provide 1,2,4-triazole derivatives. Alternative treatment of the acid hydrazide with carbon disulfide in the presence of KOH led to the corresponding 1,3,4-oxadiazole and various alkylated derivatives. The newly synthesized compounds were purified and the structures of the products were elucidated and confirmed on the basis of their analytical and spectral data. Their antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) and Ferric Reducing Antioxidant Power (FRAP) assays. The thiosemicarbazide derivatives were highly active in both antioxidant assays with the lowest IC50 value for DPPH radical scavenging. Theoretical calculations based on density functional theory (DFT) were performed to understand the relative importance of NH, SH and CH hydrogens on the radical scavenging activities of these compounds.
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Sala O, Lüthi HP, Togni A, Iannuzzi M, Hutter J. Dividing a complex reaction involving a hypervalent iodine reagent into three limiting mechanisms by ab initio molecular dynamics. J Comput Chem 2015; 36:785-94. [PMID: 25766580 DOI: 10.1002/jcc.23857] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 01/23/2015] [Accepted: 01/25/2015] [Indexed: 01/09/2023]
Abstract
The electrophilic N-trifluoromethylation of MeCN with a hypervalent iodine reagent to form a nitrilium ion, that is rapidly trapped by an azole nucleophile, is thought to occur via reductive elimination (RE). A recent study showed that, depending on the solvent representation, the S(N)2 is favoured to a different extent over the RE. However, there is a discriminative solvent effect present, which calls for a statistical mechanics approach to fully account for the entropic contributions. In this study, we perform metadynamic simulations for two trifluoromethylation reactions (with N- and S-nucleophiles), showing that the RE mechanism is always favoured in MeCN solution. These computations also indicate that a radical mechanism (single electron transfer) may play an important role. The computational protocol based on accelerated molecular dynamics for the exploration of the free energy surface is transferable and will be applied to similar reactions to investigate other electrophiles on the reagent. Based on the activation parameters determined, this approach also gives insight into the mechanistic details of the trifluoromethylation and shows that these commonly known mechanisms mark the limits within which the reaction proceeds.
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Affiliation(s)
- Oliver Sala
- ETH Zurich, Laboratorium für Physikalische Chemie, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland
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Saadi J, Brüdgam I, Reissig HU. Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations. Beilstein J Org Chem 2010; 6:1229-45. [PMID: 21283559 PMCID: PMC3028607 DOI: 10.3762/bjoc.6.141] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Accepted: 11/11/2010] [Indexed: 11/23/2022] Open
Abstract
A series of γ-oxo esters suitably substituted with various styrene subunits was subjected to samarium diiodide-induced 8-endo-trig cyclizations. Efficacy, regioselectivity and stereoselectivity of these reactions via samarium ketyls strongly depend on the substitution pattern of the attacked alkene moiety. The stereoselectivity of the protonation of the intermediate samariumorganyl is also influenced by the structural features of the substrates. This systematic study reveals that steric and electronic factors exhibited by the alkene and ketone subunits are of high importance for the outcome of these cyclization reactions leading to highly substituted benzannulated cyclooctanol derivatives. In exceptional cases, 7-exo-trig cyclizations to cycloheptanol derivatives have been observed. In examples with high steric hindrance the ketyl–aryl coupling can be a competing process.
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Affiliation(s)
- Jakub Saadi
- Freie Universität Berlin, Institut für Chemie und Biochemie, Takustrasse 3, D-14195 Berlin, Germany
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