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Krueger R, Feng E, Barzova P, Lieberman N, Lin S, Moeller KD. Anodic Cyclizations, Densely Functionalized Synthetic Building Blocks, and the Importance of Recent Mechanistic Observations. J Org Chem 2024; 89:1927-1940. [PMID: 38231008 DOI: 10.1021/acs.joc.3c02659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Anodic cyclization reactions can provide a versatile method for converting newly obtained chiral lactols to densely functionalized cyclic building blocks. The method works by first converting the lactol into an electron-rich olefin and then oxidatively generating a radical cation that is trapped by a nucleophile. Historically, such reactions have benefited from the use of less polar radical cations when the trapping nucleophile is a heteroatom and more polar radical cations when the reaction forms C-C bonds. This forced one to optimize underperforming reactions by resynthesizing the substrate. Here, we show that by taking advantage of methods that serve to drive a reversible initial cyclization reaction toward the product, this dichotomy and need to manipulate the substrate can be avoided. Two such methods were utilized: a faster second oxidation step and a mediated electrolysis. Both led to successful cyclizations using a polar radical cation and heteroatom nucleophiles.
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Affiliation(s)
- Ruby Krueger
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Enqi Feng
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Polina Barzova
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Noah Lieberman
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Song Lin
- Department of Chemistry and Biological Chemistry, Cornell University, Ithaca, New York 14853, United States
| | - Kevin D Moeller
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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2
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Takumi M, Nagaki A. Flash Synthesis and Continuous Production of C-Arylglycosides in a Flow Electrochemical Reactor. FRONTIERS IN CHEMICAL ENGINEERING 2022. [DOI: 10.3389/fceng.2022.862766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Electrochemistry provides a green and atom-efficient route to synthesize pharmaceutical and useful functional molecules, as it eliminates the need for the harsh chemical oxidants and reductants commonly used in traditional chemical reactions. To promote the implementation of electrochemical processes in the industry, there is a strong demand for the development of technologies that would allow for scale-up and a shortened reaction process time. Herein, we report that electrolysis was successfully accomplished using a flow-divided-electrochemical reactor within a few seconds, enabling the desired chemical conversion in a short period of time. Moreover, the narrow electrode gap of the flow reactor, which offers greener conditions than the conventional batch reactor, resulted in the continuous flash synthesis of C-arylglycosides.
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3
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Medcalf Z, Moeller KD. Anodic Olefin Coupling Reactions: Elucidating Radical Cation Mechanisms and the Interplay between Cyclization and Second Oxidation Steps. CHEM REC 2021; 21:2442-2452. [PMID: 34117713 DOI: 10.1002/tcr.202100118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/18/2021] [Indexed: 12/13/2022]
Abstract
Anodic olefin coupling reactions generate new bonds and ring skeletons through a net two electron process that reverses the polarity of a known, electron-rich functional group. While much of the early work on the mechanism of these reactions focused on the initial oxidation and cyclization steps of the process, the second oxidation step also plays a central role in determining the success of the reaction. Evidence supporting this observation is presented, along with evidence that optimization of this second oxidation step is not enough to pull a poor cyclization to the desired product. Successful cyclization reactions require optimization of both processes.
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Affiliation(s)
- Zach Medcalf
- Department of Chemistry, Washington University in Saint Louis, One Brookings Drive, 63130-4899, St Louis, MO, USA
| | - Kevin D Moeller
- Department of Chemistry, Washington University in Saint Louis, One Brookings Drive, 63130-4899, St Louis, MO, USA
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4
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Wu T, Moeller KD. Organic Electrochemistry: Expanding the Scope of Paired Reactions. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202100193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Tiandi Wu
- Department of Chemistry Washington University St. Louis MO 63130 USA
| | - Kevin D. Moeller
- Department of Chemistry Washington University St. Louis MO 63130 USA
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5
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Wu T, Moeller KD. Organic Electrochemistry: Expanding the Scope of Paired Reactions. Angew Chem Int Ed Engl 2021; 60:12883-12890. [PMID: 33768678 DOI: 10.1002/anie.202100193] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/23/2021] [Indexed: 12/31/2022]
Abstract
Paired electrochemical reactions allow the optimization of both atom and energy economy of oxidation and reduction reactions. While many paired electrochemical reactions take advantage of perfectly matched reactions at the anode and cathode, this matching of substrates is not necessary. In constant current electrolysis, the potential at both electrodes adjusts to the substrates in solution. In principle, any oxidation reaction can be paired with any reduction reaction. Various oxidation reactions conducted on the anodic side of the electrolysis were paired with the generation and use of hydrogen gas at the cathode, showing the generality of the anodic process in a paired electrolysis and how the auxiliary reaction required for the oxidation could be used to generate a substrate for a non-electrolysis reaction. This is combined with variations on the cathodic side of the electrolysis to complete the picture and illustrate how oxidation and reduction reactions can be combined.
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Affiliation(s)
- Tiandi Wu
- Department of Chemistry, Washington University, St. Louis, MO, 63130, USA
| | - Kevin D Moeller
- Department of Chemistry, Washington University, St. Louis, MO, 63130, USA
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6
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Phillips AMF, Pombeiro AJL. Electrochemical asymmetric synthesis of biologically active substances. Org Biomol Chem 2020; 18:7026-7055. [PMID: 32909570 DOI: 10.1039/d0ob01425g] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Electrically driven oxidation and reduction reactions are well-established methods for synthesis even in the chemical industry, but asymmetric versions are still few. The mild conditions used, atom efficiency and low cost make these reactions a very attractive alternative to other methods of synthesis. Very fine tuning can be achieved based on minute changes in potentials, allowing only one functional group in a molecule to react in the presence of several others, which is ideal for applications in total synthesis. In this review, the literature in the field of asymmetric synthesis of biologically active substances over the last 10 years is surveyed.
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Affiliation(s)
- Ana Maria Faisca Phillips
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
| | - Armando J L Pombeiro
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
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7
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Chen A, Yu H, Yan J, Huang H. Lewis Acid Catalyzed Electrophilic Aminomethyloxygenative Cyclization of Alkynols with N,O-Aminals. Org Lett 2020; 22:755-759. [DOI: 10.1021/acs.orglett.9b04630] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Anrong Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, Center for Excellence in Molecular Synthesis, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, P.R. China
| | - Houjian Yu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, Center for Excellence in Molecular Synthesis, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, P.R. China
| | - Jiaqi Yan
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, Center for Excellence in Molecular Synthesis, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, P.R. China
| | - Hanmin Huang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, Center for Excellence in Molecular Synthesis, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, P.R. China
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
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8
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Shatskiy A, Lundberg H, Kärkäs MD. Organic Electrosynthesis: Applications in Complex Molecule Synthesis. ChemElectroChem 2019. [DOI: 10.1002/celc.201900435] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Andrey Shatskiy
- Department of ChemistryKTH Royal Institute of Technology SE-100 44 Stockholm Sweden
| | - Helena Lundberg
- Department of ChemistryKTH Royal Institute of Technology SE-100 44 Stockholm Sweden
| | - Markus D. Kärkäs
- Department of ChemistryKTH Royal Institute of Technology SE-100 44 Stockholm Sweden
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9
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Wu T, Nguyen BH, Daugherty MC, Moeller KD. Paired Electrochemical Reactions and the On-Site Generation of a Chemical Reagent. Angew Chem Int Ed Engl 2019; 58:3562-3565. [DOI: 10.1002/anie.201900343] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Indexed: 11/07/2022]
Affiliation(s)
- Tiandi Wu
- Department of Chemistry; Washington University in St. Louis; St. Louis MO 63130 USA
| | - Bichlien H. Nguyen
- Department of Chemistry; Washington University in St. Louis; St. Louis MO 63130 USA
- Current address: Microsoft Research; Redmond WA, 98052 USA
| | - Michael C. Daugherty
- Department of Chemistry; Washington University in St. Louis; St. Louis MO 63130 USA
| | - Kevin D. Moeller
- Department of Chemistry; Washington University in St. Louis; St. Louis MO 63130 USA
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10
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Wu T, Nguyen BH, Daugherty MC, Moeller KD. Paired Electrochemical Reactions and the On-Site Generation of a Chemical Reagent. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201900343] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Tiandi Wu
- Department of Chemistry; Washington University in St. Louis; St. Louis MO 63130 USA
| | - Bichlien H. Nguyen
- Department of Chemistry; Washington University in St. Louis; St. Louis MO 63130 USA
- Current address: Microsoft Research; Redmond WA, 98052 USA
| | - Michael C. Daugherty
- Department of Chemistry; Washington University in St. Louis; St. Louis MO 63130 USA
| | - Kevin D. Moeller
- Department of Chemistry; Washington University in St. Louis; St. Louis MO 63130 USA
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11
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Fu N, Shen Y, Allen AR, Song L, Ozaki A, Lin S. Mn-Catalyzed Electrochemical Chloroalkylation of Alkenes. ACS Catal 2019; 9:746-754. [PMID: 31304049 DOI: 10.1021/acscatal.8b03209] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The heterodifunctionalization of alkenes is an efficient method for synthesizing highly functionalized organic molecules. In this report, we describe the use of anodically coupled electrolysis for the catalytic chloroalkylation of alkenes-a reaction that constructs vicinal C-C and C-Cl bonds in a single synthetic operation-from malononitriles or cyanoacetates and NaCl. Knowledge of the persistent radical effect guided the reaction design and development. A series of controlled experiments, including divided-cell electrolysis that compartmentalized the anodic and cathodic events, allowed us to identify the key radical intermediates and the pathway to their electrocatalytic formation. Cyclic voltammetry data further support the proposed mechanism entailing the parallel, Mn-mediated generation of two radical intermediates in an anodically coupled electrolysis followed by their selective addition to the alkene.
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Affiliation(s)
- Niankai Fu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Yifan Shen
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Anthony R. Allen
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, Ohio 44074, United States
| | - Lu Song
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Atsushi Ozaki
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
| | - Song Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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12
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Kärkäs MD. Electrochemical strategies for C-H functionalization and C-N bond formation. Chem Soc Rev 2018; 47:5786-5865. [PMID: 29911724 DOI: 10.1039/c7cs00619e] [Citation(s) in RCA: 590] [Impact Index Per Article: 98.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Conventional methods for carrying out carbon-hydrogen functionalization and carbon-nitrogen bond formation are typically conducted at elevated temperatures, and rely on expensive catalysts as well as the use of stoichiometric, and perhaps toxic, oxidants. In this regard, electrochemical synthesis has recently been recognized as a sustainable and scalable strategy for the construction of challenging carbon-carbon and carbon-heteroatom bonds. Here, electrosynthesis has proven to be an environmentally benign, highly effective and versatile platform for achieving a wide range of nonclassical bond disconnections via generation of radical intermediates under mild reaction conditions. This review provides an overview on the use of anodic electrochemical methods for expediting the development of carbon-hydrogen functionalization and carbon-nitrogen bond formation strategies. Emphasis is placed on methodology development and mechanistic insight and aims to provide inspiration for future synthetic applications in the field of electrosynthesis.
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Affiliation(s)
- Markus D Kärkäs
- Department of Chemistry, Organic Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
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13
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Shi YG, Mellerup SK, Yuan K, Hu GF, Sauriol F, Peng T, Wang N, Chen P, Wang S. Stabilising fleeting intermediates of stilbene photocyclization with amino-borane functionalisation: the rare isolation of persistent dihydrophenanthrenes and their [1,5] H-shift isomers. Chem Sci 2018; 9:3844-3855. [PMID: 29887983 PMCID: PMC5946680 DOI: 10.1039/c8sc00560e] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 03/26/2018] [Indexed: 11/21/2022] Open
Abstract
Amino-borane functionalization is the key for isolating rare air-stable dihydrophenanthrene intermediates in stilbene photocyclization.
The key intermediate, 4a,4b-dihydrophenanthrene (DPH), involved in the photocyclization of stilbene and derivatives is known to be unstable, and is therefore poorly characterized/understood. We have found that functionalising stilbenes with NMe2 and BMes2 groups can greatly enhance the stability of 4a,4b-DPHs, allowing quantitative isolation and full characterization of these rare species. Furthermore, we discovered that the new amino-borane decorated 4a,4b-DPHs can undergo thermal [1,5] H sigmatropic shift, forming isomers 4a,10a-DPHs. Both 4a,4b-DHPs and 4a,10a-DHPs are stable towards air and moisture, while only the former were found to undergo oxidative dehydrogenation upon irradiation at 365 nm under air, yielding brightly blue/green fluorescent NMe2 and BMes2 functionalised phenanthrene analogues. Control studies established that the trans-Mes2B–Ph–NMe2 unit is responsible for the stability of these isolated 4a,4b-DHPs and their [1,5]-H shift isomers.
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Affiliation(s)
- Yong-Gang Shi
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials , School of Chemistry , Beijing Institute of Technology , Beijing 100081 , P. R. China
| | - Soren K Mellerup
- Department of Chemistry , Queen's University , Kingston , Ontario K7L 3N6 , Canada .
| | - Kang Yuan
- Department of Chemistry , Queen's University , Kingston , Ontario K7L 3N6 , Canada .
| | - Guo-Fei Hu
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials , School of Chemistry , Beijing Institute of Technology , Beijing 100081 , P. R. China
| | - Francoise Sauriol
- Department of Chemistry , Queen's University , Kingston , Ontario K7L 3N6 , Canada .
| | - Tai Peng
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials , School of Chemistry , Beijing Institute of Technology , Beijing 100081 , P. R. China
| | - Nan Wang
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials , School of Chemistry , Beijing Institute of Technology , Beijing 100081 , P. R. China
| | - Pangkuan Chen
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials , School of Chemistry , Beijing Institute of Technology , Beijing 100081 , P. R. China
| | - Suning Wang
- Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials , School of Chemistry , Beijing Institute of Technology , Beijing 100081 , P. R. China.,Department of Chemistry , Queen's University , Kingston , Ontario K7L 3N6 , Canada .
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14
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Moeller KD. Using Physical Organic Chemistry To Shape the Course of Electrochemical Reactions. Chem Rev 2018; 118:4817-4833. [DOI: 10.1021/acs.chemrev.7b00656] [Citation(s) in RCA: 373] [Impact Index Per Article: 62.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kevin D. Moeller
- Washington University in St. Louis, St. Louis, Missouri 63130, United States
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15
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Zhang L, Zhang Z, Hong J, Yu J, Zhang J, Mo F. Oxidant-Free C(sp 2)-H Functionalization/C-O Bond Formation: A Kolbe Oxidative Cyclization Process. J Org Chem 2018; 83:3200-3207. [PMID: 29471627 DOI: 10.1021/acs.joc.8b00089] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An anodic oxidation/cyclization of 2-arylbenzoic acids for the synthesis of dibenzopyranones has been developed. The reaction proceeds at room temperature with no oxidant or electrolyte required and exhibits a high atom economy with H2 being the only byproduct. A series of dibenzopyranones was obtained in good to excellent yields. Urolithins A, B, and C are formally synthesized by adopting this method as a key step to demonstrate its synthetic utility.
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Affiliation(s)
- Lei Zhang
- Department of Energy and Resources Engineering, College of Engineering , Peking University , Beijing 100871 , China
| | - Zhenxing Zhang
- Department of Energy and Resources Engineering, College of Engineering , Peking University , Beijing 100871 , China
| | - Junting Hong
- Department of Energy and Resources Engineering, College of Engineering , Peking University , Beijing 100871 , China
| | - Jian Yu
- Department of Energy and Resources Engineering, College of Engineering , Peking University , Beijing 100871 , China
| | - Jianning Zhang
- Department of Energy and Resources Engineering, College of Engineering , Peking University , Beijing 100871 , China
| | - Fanyang Mo
- Department of Energy and Resources Engineering, College of Engineering , Peking University , Beijing 100871 , China
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16
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Lennox AJJ, Nutting JE, Stahl SS. Selective electrochemical generation of benzylic radicals enabled by ferrocene-based electron-transfer mediators. Chem Sci 2018; 9:356-361. [PMID: 29732109 PMCID: PMC5909123 DOI: 10.1039/c7sc04032f] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 10/25/2017] [Indexed: 11/25/2022] Open
Abstract
The generation and intermolecular functionalisation of carbon-centred radicals has broad potential synthetic utility. Herein, we show that benzylic radicals may be generated electrochemically from benzylboronate derivatives at low electrode potentials (ca. -0.3 V vs. Cp2Fe0/+) via single electron oxidation. Use of a catalytic quantity of a ferrocene-based electron-transfer mediator is crucial to achieve successful radical functionalisation and avoid undesirable side reactions arising from direct electrochemical oxidation or from the use of stoichiometric ferrocenium-based oxidants.
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Affiliation(s)
- Alastair J J Lennox
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , USA .
| | - Jordan E Nutting
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , USA .
| | - Shannon S Stahl
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706 , USA .
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17
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Yan M, Kawamata Y, Baran PS. Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance. Chem Rev 2017; 117:13230-13319. [PMID: 28991454 PMCID: PMC5786875 DOI: 10.1021/acs.chemrev.7b00397] [Citation(s) in RCA: 1932] [Impact Index Per Article: 276.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Electrochemistry represents one of the most intimate ways of interacting with molecules. This review discusses advances in synthetic organic electrochemistry since 2000. Enabling methods and synthetic applications are analyzed alongside innate advantages as well as future challenges of electroorganic chemistry.
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Affiliation(s)
| | | | - Phil S. Baran
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
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18
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Affiliation(s)
- Yangye Jiang
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, China
| | - Kun Xu
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, China
- College of Chemistry and Pharmaceutical Engineering, Nanyang Normal University, Nanyang, Henan 473061, China
| | - Chengchu Zeng
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, China
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19
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Abstract
The preparation and transformation of heterocyclic structures have always been of great interest in organic chemistry. Electrochemical technique provides a versatile and powerful approach to the assembly of various heterocyclic structures. In this review, we examine the advance in relation to the electrochemical construction of heterocyclic compounds published since 2000 via intra- and intermolecular cyclization reactions.
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Affiliation(s)
- Yangye Jiang
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering , Beijing University of Technology , Beijing 100124 , China
| | - Kun Xu
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering , Beijing University of Technology , Beijing 100124 , China.,College of Chemistry and Pharmaceutical Engineering , Nanyang Normal University , Nanyang , Henan 473061 , China
| | - Chengchu Zeng
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering , Beijing University of Technology , Beijing 100124 , China
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20
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Feng R, Smith JA, Moeller KD. Anodic Cyclization Reactions and the Mechanistic Strategies That Enable Optimization. Acc Chem Res 2017; 50:2346-2352. [PMID: 28858480 DOI: 10.1021/acs.accounts.7b00287] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Oxidation reactions are powerful tools for synthesis because they allow us to reverse the polarity of electron-rich functional groups, generate highly reactive intermediates, and increase the functionality of molecules. For this reason, oxidation reactions have been and continue to be the subject of intense study. Central to these efforts is the development of mechanism-based strategies that allow us to think about the reactive intermediates that are frequently central to the success of the reactions and the mechanistic pathways that those intermediates trigger. For example, consider oxidative cyclization reactions that are triggered by the removal of an electron from an electron-rich olefin and lead to cyclic products that are functionalized for further elaboration. For these reactions to be successful, the radical cation intermediate must first be generated using conditions that limit its polymerization and then channeled down a productive desired pathway. Following the cyclization, a second oxidation step is necessary for product formation, after which the resulting cation must be quenched in a controlled fashion to avoid undesired elimination reactions. Problems can arise at any one or all of these steps, a fact that frequently complicates reaction optimization and can discourage the development of new transformations. Fortunately, anodic electrochemistry offers an outstanding opportunity to systematically probe the mechanism of oxidative cyclization reactions. The use of electrochemical methods allows for the generation of radical cations under neutral conditions in an environment that helps prevent polymerization of the intermediate. Once the intermediates have been generated, a series of "telltale indicators" can be used to diagnose which step in an oxidative cyclization is problematic for less successful transformation. A set of potential solutions to address each type of problem encountered has been developed. For example, problems with the initial cyclization reaction leading to either polymerization of the radical cation, elimination of a proton from or solvent trapping of that intermediate, or solvent trapping of the radical cation can be identified in the proton NMR spectrum of the crude reaction material. Such an NMR spectrum shows retention of the trapping group. The problems can be addressed by tuning the radical cation, altering the trapping group, or channeling the reactive intermediate down a radical pathway. Specific examples each are shown in this Account. Problems with the second oxidation step can be identified by poor current efficiency or general decomposition in spite of cyclic voltammetry evidence for a rapid cyclization. Solutions involve improving the oxidation conditions for the radical after cyclization by either the addition of a properly placed electron-donating group in the substrate or an increase in the concentration of electrolyte in the reaction (a change that stabilizes the cation generated from the second oxidation step). Problems with the final cation typically lead to overoxidation. Solutions to this problem require an approach that either slows down elimination side reactions or changes the reaction conditions so that the cation can be quickly trapped in an irreversible fashion. Again, this Account highlights these strategies along with the specific experimental protocols utilized.
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Affiliation(s)
- Ruozhu Feng
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Jake A. Smith
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Kevin D. Moeller
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
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21
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Affiliation(s)
- You Yang
- Shanghai
Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Biao Yu
- State
Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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22
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Al Mousawi A, Dumur F, Garra P, Toufaily J, Hamieh T, Goubard F, Bui TT, Graff B, Gigmes D, Pierre Fouassier J, Lalevée J. Azahelicenes as visible light photoinitiators for cationic and radical polymerization: Preparation of photoluminescent polymers and use in high performance LED projector 3D printing resins. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/pola.28476] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Assi Al Mousawi
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361 - UHA, 15, rue Jean Starcky; 68057 Mulhouse Cedex France
- Laboratoire de Matériaux, Catalyse, Environnement et Méthodes analytiques (MCEMA-CHAMSI), EDST, Université Libanaise, Campus Hariri, Hadath; Beyrouth Liban
| | - Frédéric Dumur
- Aix Marseille Univ; CNRS, ICR UMR 7273 Marseille F-13397 France
| | - Patxi Garra
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361 - UHA, 15, rue Jean Starcky; 68057 Mulhouse Cedex France
| | - Joumana Toufaily
- Laboratoire de Matériaux, Catalyse, Environnement et Méthodes analytiques (MCEMA-CHAMSI), EDST, Université Libanaise, Campus Hariri, Hadath; Beyrouth Liban
| | - Tayssir Hamieh
- Laboratoire de Matériaux, Catalyse, Environnement et Méthodes analytiques (MCEMA-CHAMSI), EDST, Université Libanaise, Campus Hariri, Hadath; Beyrouth Liban
| | - Fabrice Goubard
- Laboratoire de Physicochimie des Polymères et des Interfaces (LPPI), Université de Cergy-Pontoise; 5 mail Gay Lussac, Neuville-sur-Oise, 95031 Cergy-Pontoise Cedex France
| | - Thanh-Tuân Bui
- Laboratoire de Physicochimie des Polymères et des Interfaces (LPPI), Université de Cergy-Pontoise; 5 mail Gay Lussac, Neuville-sur-Oise, 95031 Cergy-Pontoise Cedex France
| | - Bernadette Graff
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361 - UHA, 15, rue Jean Starcky; 68057 Mulhouse Cedex France
| | - Didier Gigmes
- Aix Marseille Univ; CNRS, ICR UMR 7273 Marseille F-13397 France
| | - Jean Pierre Fouassier
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361 - UHA, 15, rue Jean Starcky; 68057 Mulhouse Cedex France
| | - Jacques Lalevée
- Institut de Science des Matériaux de Mulhouse IS2M - UMR CNRS 7361 - UHA, 15, rue Jean Starcky; 68057 Mulhouse Cedex France
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23
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Smith JA, Xu G, Feng R, Janetka JW, Moeller KD. C‐Glycosides, Array‐based Addressable Libraries, and the Versatility of Constant Current Electrochemistry. ELECTROANAL 2016. [DOI: 10.1002/elan.201600200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
| | | | | | - James W. Janetka
- Department of Biochemistry and Molecular Biophysics School of Medicine Washington University St. Louis MO 63130
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24
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Horn EJ, Rosen BR, Baran PS. Synthetic Organic Electrochemistry: An Enabling and Innately Sustainable Method. ACS CENTRAL SCIENCE 2016; 2:302-8. [PMID: 27280164 PMCID: PMC4882743 DOI: 10.1021/acscentsci.6b00091] [Citation(s) in RCA: 625] [Impact Index Per Article: 78.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Indexed: 05/21/2023]
Abstract
While preparative electrolysis of organic molecules has been an active area of research over the past century, modern synthetic chemists have generally been reluctant to adopt this technology. In fact, electrochemical methods possess many benefits over traditional reagent-based transformations, such as high functional group tolerance, mild conditions, and innate scalability and sustainability. In this Outlook we highlight illustrative examples of electrochemical reactions in the context of the synthesis of complex molecules, showcasing the intrinsic benefits of electrochemical reactions versus traditional reagent-based approaches. Our hope is that this field will soon see widespread adoption in the synthetic community.
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25
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Rensing DT, Nguyen BH, Moeller KD. Considering organic mechanisms and the optimization of current flow in an electrochemical oxidative condensation reaction. Org Chem Front 2016. [DOI: 10.1039/c6qo00248j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Careful consideration of the chemical mechanism for an oxidative condensation reaction led to improved current flow for the electrolysis.
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Affiliation(s)
- Derek T. Rensing
- Department of Chemistry
- Washington University in St. Louis
- St. Louis
- USA
| | | | - Kevin D. Moeller
- Department of Chemistry
- Washington University in St. Louis
- St. Louis
- USA
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26
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Nguyen BH, Perkins RJ, Smith JA, Moeller KD. Solvolysis, Electrochemistry, and Development of Synthetic Building Blocks from Sawdust. J Org Chem 2015; 80:11953-62. [PMID: 26544912 DOI: 10.1021/acs.joc.5b01776] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Either aldehyde or cinnamyl ether products can be selectively extracted from raw sawdust by controlling the temperature and pressure of a solvolysis reaction. These materials have been used as platform chemicals for the synthesis of 15 different synthetic substrates. The conversion of the initial sawdust-derived materials into electron-rich aryl substrates often requires the use of oxidation and reduction chemistry, and the role electrochemistry can play as a sustainable method for these transformations has been defined.
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Affiliation(s)
- Bichlien H Nguyen
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Robert J Perkins
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Jake A Smith
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Kevin D Moeller
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States
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27
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Campbell JM, Smith JA, Gonzalez L, Moeller KD. Competition studies and the relative reactivity of enol ether and allylsilane coupling partners toward ketene dithioacetal derived radical cations. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2015.01.144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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28
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Nguyen BH, Perkins RJ, Smith JA, Moeller KD. Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions. Beilstein J Org Chem 2015; 11:280-7. [PMID: 25815081 PMCID: PMC4361993 DOI: 10.3762/bjoc.11.32] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 02/09/2015] [Indexed: 12/15/2022] Open
Abstract
The combination of visible light, photovoltaics, and electrochemistry provides a convenient, inexpensive platform for conducting a wide variety of sustainable oxidation reactions. The approach presented in this article is compatible with both direct and indirect oxidation reactions, avoids the need for a stoichiometric oxidant, and leads to hydrogen gas as the only byproduct from the corresponding reduction reaction.
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Affiliation(s)
- Bichlien H Nguyen
- Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Robert J Perkins
- Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Jake A Smith
- Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
| | - Kevin D Moeller
- Washington University in Saint Louis, Saint Louis, Missouri 63130, United States
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29
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Graaf MD, Moeller KD. Photoredox Catalysts: Synthesis of the Bipyrazine Ligand. J Org Chem 2015; 80:2032-5. [DOI: 10.1021/jo502925u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew D. Graaf
- Department
of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Kevin D. Moeller
- Department
of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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30
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Romero NA, Nicewicz DA. Mechanistic insight into the photoredox catalysis of anti-markovnikov alkene hydrofunctionalization reactions. J Am Chem Soc 2014; 136:17024-35. [PMID: 25390821 PMCID: PMC4277776 DOI: 10.1021/ja506228u] [Citation(s) in RCA: 242] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
We describe our efforts to understand
the key mechanistic aspects
of the previously reported alkene hydrofunctionalization reactions
using 9-mesityl-10-methylacridinium (Mes-Acr+) as a photoredox catalyst. Importantly, we are able
to detect alkene cation radical intermediates, and confirm that phenylthiyl
radical is capable of oxidizing the persistent acridinyl radical in
a fast process that unites the catalytic activity of the photoredox
and hydrogen atom transfer (HAT) manifolds. Additionally, we present
evidence that diphenyl disulfide ((PhS)2)
operates on a common catalytic cycle with thiophenol (PhSH) by way of photolytic cleaveage of the disulfide bond. Transition
structure analysis of the HAT step using DFT reveals that the activation
barrier for H atom donation from PhSH is significantly
lower than 2-phenylmalononitrile (PMN) due to structural
reorganization. In the early stages of the reaction, Mes-Acr+ is observed to engage in off-cycle adduct
formation, presumably as buildup of PhS− becomes significant. The kinetic differences between PhSH and (PhS)2 as HAT catalysts indicate that
the proton transfer step may have significant rate limiting influence.
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Affiliation(s)
- Nathan A Romero
- Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States
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31
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Nicewicz DA, Hamilton DS. Organic Photoredox Catalysis as a General Strategy for Anti-Markovnikov Alkene Hydrofunctionalization. Synlett 2014; 25:1191-1196. [PMID: 29657365 PMCID: PMC5895094 DOI: 10.1055/s-0033-1340738] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The development of a general catalyst system for the direct anti-Markovnikov hydrofunctionalization of alkenes is presented. A unique catalyst system comprised of an acridinium photooxidant and a hydrogen atom transfer reagent allows for a range of alkene anti-Markovnikov hydrofunctionalization reactions including hydroalkoxylation, hydroamination, and hydroacetoxylation.
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Affiliation(s)
- David A. Nicewicz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA
| | - David S. Hamilton
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA
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32
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Xu HC, Campbell JM, Moeller KD. Cyclization Reactions of Anode-Generated Amidyl Radicals. J Org Chem 2013; 79:379-91. [DOI: 10.1021/jo402623r] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Hai-Chao Xu
- Department
of Chemistry and Fujian Provincial Key Laboratory of Chemical Biology,
College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - John M. Campbell
- Department
of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Kevin D. Moeller
- Department
of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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