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Quiclet-Sire B, Zard SZ. Some Aspects of α-(Acyloxy)alkyl Radicals in Organic Synthesis. Molecules 2023; 28:7561. [PMID: 38005282 PMCID: PMC10673534 DOI: 10.3390/molecules28227561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/08/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023] Open
Abstract
The preparation and use of α-(acyloxy)alkyl xanthates to generate and capture α-(acyloxy)alkyl radicals is briefly reviewed. Their inter- and intramolecular additions to both activated and unactivated, electronically unbiased, alkenes, and to (hetero)aromatic rings, as well as their radical allylation and vinylation reactions are described. Application to the total synthesis of two 4-hydroxytetralone natural products is also presented.
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Affiliation(s)
| | - Samir Z. Zard
- Laboratoire de Synthèse Organique associé au C.N.R.S., UMR 7652, Ecole Polytechnique, 91128 Palaiseau, France;
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2
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Matsumoto A, Maeda N, Maruoka K. Bidirectional Elongation Strategy Using Ambiphilic Radical Linchpin for Modular Access to 1,4-Dicarbonyls via Sequential Photocatalysis. J Am Chem Soc 2023; 145:20344-20354. [PMID: 37490759 DOI: 10.1021/jacs.3c05337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Organic molecules that can be connected to multiple substrates by sequential C-C bond formations can be utilized as linchpins in multicomponent processes. While they are useful for rapidly increasing molecular complexity, most of the reported linchpin coupling methods rely on the use of organometallic species as strong carbon nucleophiles to form C-C bonds, which narrows the functional group compatibility. Here, we describe a metal-free, radical-mediated coupling approach using a formyl-stabilized phosphonium ylide as a multifunctional linchpin under visible-light photoredox conditions. The present method uses the ambiphilic character of the phosphonium ylide, which serves as both a nucleophilic and an electrophilic carbon-centered radical source. The stepwise and controllable generation of these radical intermediates allows sequential photocatalysis involving two mechanistically distinct radical additions, both of which are initiated by the same photocatalyst in one pot with high functional group tolerance. The methodology enables a bidirectional assembly of the linchpin with two electronically differentiated alkene fragments and thus offers rapid and modular access to 1,4-dicarbonyl compounds as versatile synthetic intermediates.
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Affiliation(s)
- Akira Matsumoto
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Natsumi Maeda
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Keiji Maruoka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
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3
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Rajai-Daryasarei S, Hosseini MS, Balalaie S. Chemoselective Reduction of α,β-Unsaturated Carbonyl Compounds via a CS 2/ t-BuOK System: Dimethyl Sulfoxide as a Hydrogen Source. J Org Chem 2023. [PMID: 37471258 DOI: 10.1021/acs.joc.3c00903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023]
Abstract
A novel and practical approach to access saturated ketones from unsaturated ketone derivatives via a CS2/t-BuOK system in dimethyl sulfoxide (DMSO) is reported. The in situ generation of xanthate salt through the reaction of carbon disulfide and potassium tert-butoxide is essential to this transformation. Deuterium-labeling experiments demonstrated that DMSO can act as a hydrogen donor.
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Affiliation(s)
- Saideh Rajai-Daryasarei
- Peptide Chemistry Research Institute, K. N. Toosi University of Technology, P.O. Box 15875-4416, Tehran 19697-64499, Iran
| | - Mir Sadra Hosseini
- Peptide Chemistry Research Institute, K. N. Toosi University of Technology, P.O. Box 15875-4416, Tehran 19697-64499, Iran
| | - Saeed Balalaie
- Peptide Chemistry Research Institute, K. N. Toosi University of Technology, P.O. Box 15875-4416, Tehran 19697-64499, Iran
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4
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Zard SZ. Sulfur chemistry in action. New perspectives for organic synthesis. PHOSPHORUS SULFUR 2023. [DOI: 10.1080/10426507.2023.2173755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Samir Z. Zard
- Laboratoire de Synthèse Organique associé au C. N. R. S., UMR 7652, Ecole Polytechnique, Palaiseau, France
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5
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Boyer C, Kamigaito M, Satoh K, Moad G. Radical-Promoted Single-unit Monomer Insertion (SUMI) [aka. Reversible-Deactivation Radical Addition (RDRA)]. Prog Polym Sci 2023. [DOI: 10.1016/j.progpolymsci.2023.101648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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6
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Li J, Li J, Ji X, Liu Q, Chen L, Huang Y, Li Y. Transition Metal‐Free Synthesis of Substituted Isothiazoles
via
Three‐Component Annulation of Alkynones, Xanthate and NH
4
I. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202001179] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jian Li
- School of Biotechnology and Health Sciences Wuyi University Jiangmen, Guangdong Province 529090 People's Republic of China
| | - Jiaming Li
- School of Biotechnology and Health Sciences Wuyi University Jiangmen, Guangdong Province 529090 People's Republic of China
| | - Xiaoliang Ji
- School of Biotechnology and Health Sciences Wuyi University Jiangmen, Guangdong Province 529090 People's Republic of China
| | - Qiang Liu
- School of Biotechnology and Health Sciences Wuyi University Jiangmen, Guangdong Province 529090 People's Republic of China
- Center of Basic Molecular Science Department of Chemistry Tsinghua University Beijing 100084 People's Republic of China
| | - Lu Chen
- School of Biotechnology and Health Sciences Wuyi University Jiangmen, Guangdong Province 529090 People's Republic of China
| | - Yubing Huang
- School of Biotechnology and Health Sciences Wuyi University Jiangmen, Guangdong Province 529090 People's Republic of China
| | - Yibiao Li
- School of Biotechnology and Health Sciences Wuyi University Jiangmen, Guangdong Province 529090 People's Republic of China
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7
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Abstract
Photochemical transformations of molecular building blocks have become an important and widely recognized research field in the past decade. Detailed and deep understanding of novel photochemical catalysts and reaction concepts with visible light as the energy source has enabled a broad application portfolio for synthetic organic chemistry. In parallel, continuous-flow chemistry and microreaction technology have become the basis for thinking and doing chemistry in a novel fashion with clear focus on improved process control for higher conversion and selectivity. As can be seen by the large number of scientific publications on flow photochemistry in the recent past, both research topics have found each other as exceptionally well-suited counterparts with high synergy by combining chemistry and technology. This review will give an overview on selected reaction classes, which represent important photochemical transformations in synthetic organic chemistry, and which benefit from mild and defined process conditions by the transfer from batch to continuous-flow mode.
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Affiliation(s)
- Thomas H. Rehm
- Division Energy & Chemical Technology/Flow Chemistry GroupFraunhofer Institute for Microengineering and Microsystems IMMCarl-Zeiss-Straße 18–2055129MainzGermany
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8
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Abstract
A general method for the hydroalkylation of electron-rich terminal and non-terminal alkenes such as enol esters, alkenyl sulfides, enol ethers, silyl enol ethers, enamides and enecarbamates has been developed. The reactions are carried out at room temperature under air initiation in the presence of triethylborane acting as a chain transfer reagent and 4-tert-butylcatechol (TBC) as a source of hydrogen atom. The efficacy of the reaction is best explained by very favorable polar effects supporting the chain process and minimizing undesired polar reactions. The stereoselective hydroalkylation of chiral N-(alk-1-en-1-yl)oxazolidin-2-ones takes place with good to excellent diastereocontrol. Giese reaction not anymore limited to electron poor alkenes! A general method for the radical mediated hydroalkylation of electron rich alkenes including enol ethers, silylenolethers, enamides, and enecarbamates has been developed.![]()
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Affiliation(s)
- Qi Huang
- Department of Chemistry and Biochemistry, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Sankar Rao Suravarapu
- Department of Chemistry and Biochemistry, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Philippe Renaud
- Department of Chemistry and Biochemistry, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
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9
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Affiliation(s)
- Nicholas D. C. Tappin
- University of Bern Department of Chemistry and Biochemistry Freiestrasse 3 3012 Bern Switzerland)
| | - Philippe Renaud
- University of Bern Department of Chemistry and Biochemistry Freiestrasse 3 3012 Bern Switzerland)
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10
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Li Y, Li F, Shi S. Expedient Synthesis of Ketones
via
N
‐Heterocyclic
Carbene/
Nickel‐Catalyzed Redox‐Economical
Coupling of Alcohols and Alkynes
†. CHINESE J CHEM 2020. [DOI: 10.1002/cjoc.202000019] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Yu‐Qing Li
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Feng Li
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Shi‐Liang Shi
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
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11
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Mathi GR, Jeong Y, Moon Y, Hong S. Photochemical Carbopyridylation of Alkenes Using
N
‐Alkenoxypyridinium Salts as Bifunctional Reagents. Angew Chem Int Ed Engl 2020; 59:2049-2054. [DOI: 10.1002/anie.201913320] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/11/2019] [Indexed: 02/05/2023]
Affiliation(s)
- Gangadhar Rao Mathi
- Center for Catalytic Hydrocarbon FunctionalizationsInstitute for Basic Science (IBS) Daejeon 34141 Republic of Korea
- Department of ChemistryKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Yujin Jeong
- Center for Catalytic Hydrocarbon FunctionalizationsInstitute for Basic Science (IBS) Daejeon 34141 Republic of Korea
- Department of ChemistryKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Yonghoon Moon
- Center for Catalytic Hydrocarbon FunctionalizationsInstitute for Basic Science (IBS) Daejeon 34141 Republic of Korea
- Department of ChemistryKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Sungwoo Hong
- Center for Catalytic Hydrocarbon FunctionalizationsInstitute for Basic Science (IBS) Daejeon 34141 Republic of Korea
- Department of ChemistryKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
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12
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Huang G, Li J, Ji X, Chen L, Liu Q, Chen X, Huang Y, Li Y. Access to 4-substituted isothiazoles through three-component cascade annulation and their application in C–H activation. Chem Commun (Camb) 2020; 56:5763-5766. [DOI: 10.1039/d0cc01100b] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The use of EtOCS2k enabled the annulation of isopropene derivatives with NH4I, affording various 4-substituted isothiazoles in good yields.
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Affiliation(s)
- Guoling Huang
- School of Biotechnology and Health Sciences
- Wuyi University
- Jiangmen
- China
| | - Jian Li
- School of Biotechnology and Health Sciences
- Wuyi University
- Jiangmen
- China
| | - Xiaoliang Ji
- School of Biotechnology and Health Sciences
- Wuyi University
- Jiangmen
- China
| | - Lu Chen
- School of Biotechnology and Health Sciences
- Wuyi University
- Jiangmen
- China
| | - Qiang Liu
- School of Biotechnology and Health Sciences
- Wuyi University
- Jiangmen
- China
- Center of Basic Molecular Science
| | - Xiuwen Chen
- School of Biotechnology and Health Sciences
- Wuyi University
- Jiangmen
- China
| | - Yubing Huang
- School of Biotechnology and Health Sciences
- Wuyi University
- Jiangmen
- China
| | - Yibiao Li
- School of Biotechnology and Health Sciences
- Wuyi University
- Jiangmen
- China
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13
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14
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Mathi GR, Jeong Y, Moon Y, Hong S. Photochemical Carbopyridylation of Alkenes Using
N
‐Alkenoxypyridinium Salts as Bifunctional Reagents. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201913320] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Gangadhar Rao Mathi
- Center for Catalytic Hydrocarbon FunctionalizationsInstitute for Basic Science (IBS) Daejeon 34141 Republic of Korea
- Department of ChemistryKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Yujin Jeong
- Center for Catalytic Hydrocarbon FunctionalizationsInstitute for Basic Science (IBS) Daejeon 34141 Republic of Korea
- Department of ChemistryKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Yonghoon Moon
- Center for Catalytic Hydrocarbon FunctionalizationsInstitute for Basic Science (IBS) Daejeon 34141 Republic of Korea
- Department of ChemistryKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
| | - Sungwoo Hong
- Center for Catalytic Hydrocarbon FunctionalizationsInstitute for Basic Science (IBS) Daejeon 34141 Republic of Korea
- Department of ChemistryKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
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15
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16
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Luo X, Li Y, Chen X, Song Z, Liang J, Liao C, Zhu Z, Chen L. (Z)-Tetrahydrothiophene and (Z)-tetrahydrothiopyran synthesis through nucleophilic substitution and intramolecular cycloaddition of alkynyl halides and EtOCS 2K. Org Biomol Chem 2019; 17:7315-7319. [PMID: 31342046 DOI: 10.1039/c9ob01370a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This protocol provides a novel, environmentally friendly and simple method for the synthesis of (Z)-tetrahydrothiophene derivatives using the nucleophilic thiyl radical intramolecular cycloaddition cascade process to construct C-S bonds under transition-metal-free conditions. This transformation process offers a broad substrate scope, good functional group tolerance, and excellent stereoselectivity (Z/E ratios up to 99/1). Moreover, the process uses odourless, stable and cheap EtOCS2K as the sulfur source.
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Affiliation(s)
- Xianglin Luo
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, Guangdong Province 529020, China.
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17
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Luo X, Chen X, Chen L, Zhang K, Li Y. Xanthate-mediated synthesis of (E)-alkenes by semi-hydrogenation of alkynes using water as the hydrogen donor. Chem Commun (Camb) 2019; 55:2170-2173. [PMID: 30698604 DOI: 10.1039/c9cc00128j] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Semi-hydrogenation of alkynes is one of the most widely used methods for obtaining alkenes in laboratory preparation and in industry. Transition metal catalysts have been extensively studied for this transformation, but the tolerance of functional groups, such as pyridine, -OH, -NH2, -Bpin, and halides, and the toxicity of the trace amount of transition metal catalysts are still highly challenging. In this study, we report a general and robust strategy to achieve the semi-hydrogenation of alkynes using inexpensive and commercially available xanthate as the mediator. Mechanism studies support a non-radical process and H2O acts as the hydrogen donor.
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Affiliation(s)
- Xianglin Luo
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, Guangdong Province 529090, China.
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18
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Cartier A, Levernier E, Corcé V, Fukuyama T, Dhimane A, Ollivier C, Ryu I, Fensterbank L. Carbonylation of Alkyl Radicals Derived from Organosilicates through Visible‐Light Photoredox Catalysis. Angew Chem Int Ed Engl 2019; 58:1789-1793. [DOI: 10.1002/anie.201811858] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Alex Cartier
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
| | - Etienne Levernier
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Vincent Corcé
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Takahide Fukuyama
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
| | - Anne‐Lise Dhimane
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Cyril Ollivier
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Ilhyong Ryu
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
- Department of Applied ChemistryNational Chiao Tung University Hsinchu Taiwan
| | - Louis Fensterbank
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
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19
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Cartier A, Levernier E, Corcé V, Fukuyama T, Dhimane A, Ollivier C, Ryu I, Fensterbank L. Carbonylation of Alkyl Radicals Derived from Organosilicates through Visible‐Light Photoredox Catalysis. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201811858] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Alex Cartier
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
| | - Etienne Levernier
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Vincent Corcé
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Takahide Fukuyama
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
| | - Anne‐Lise Dhimane
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Cyril Ollivier
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
| | - Ilhyong Ryu
- Department of ChemistryGraduate School of ScienceOsaka Prefecture University Sakai Osaka 599-8531 Japan
- Department of Applied ChemistryNational Chiao Tung University Hsinchu Taiwan
| | - Louis Fensterbank
- Sorbonne UniversitéCNRSInstitut Parisien de Chimie Moléculaire 4 Place Jussieu, CC 229 75252 Paris Cedex 05 France
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21
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Matsubara H, Kawamoto T, Fukuyama T, Ryu I. Applications of Radical Carbonylation and Amine Addition Chemistry: 1,4-Hydrogen Transfer of 1-Hydroxylallyl Radicals. Acc Chem Res 2018; 51:2023-2035. [PMID: 30137961 DOI: 10.1021/acs.accounts.8b00278] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1,4-Hydrogen transfer from the 1-hydroxyallyl radical to give the enoxyl (α-keto) radical is an exothermic process with a high activation energy based on DFT calculations. The lack of experimental examples of such 1,4-H shift reactions lies in the difficulty of generating the 1-hydroxyallyl radical. We have shown that radical carbonylation of alkenyl radicals with CO followed by nucleophilic trapping of the carbonyl portion of the resulting radical by amines gives rise to 1-amino-substituted 1-hydroxyallyl radicals in situ. At the outset of this chemistry, we examined intramolecular trapping reactions via radical carbonylation of alkynylamines mediated by tributyltin hydride. Consequently, α-methylene lactams were obtained, for which the initially formed 1-amino-substituted 1-hydroxyallyl radical underwent a 1,4-H shift followed by subsequent β-scission, which led to the expulsion of a tributyltin radical. A competing pathway of the 1,4-H shift of 1-amino-substituted 1-hydroxyallyl radicals involving hydrogen abstraction was observed, which led to the formation of α-stannylmethylene lactams as a major byproduct. However, in contrast, when intermolecular trapping of α-ketenyl radicals by amines was carried out, the 1,4-H shift from the 1-amino-substituted 1-hydroxyallyl radical became the major pathway, which gave good yields of α,β-unsaturated amides. Thus, we were able to develop three-component reactions comprising terminal alkynes, CO, and amines that led to α,β-unsaturated amides via the 1,4-H shift reaction. DFT calculations support the observation that the 1,4-H shift is more facile when 1-hydroxyallyl radicals have both 1-amino and 3-tin substituents. The choice of substituents on the amine nitrogen is also important, since N-C bond cleavage via an SH2-type reaction can become a competing pathway. Such an unusual SH2-type reaction at the amine nitrogen is favored when the leaving alkyl radicals are stable, such as PhC(•)H(CH3) and t-Bu•. Interestingly, even nucleophilic attack of tertiary amines onto α-ketenyl radicals causes cleavage of the C-N bond. For this reaction, DFT calculations predict an indirect homolytic substitution mechanism involving expulsion of alkyl radicals through the zwitterionic radical intermediate arising from nucleophilic amine addition onto the α-ketenyl radical. In contrast, the carbonylation of aryl radicals, generated from aryl iodides, in the presence of amines gave aromatic carboxylic amides in good yields. It is proposed that radical anions originating from acyl radicals and amines undergo electron transfer to aryl iodides to give aminocarbonylation products.
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Affiliation(s)
- Hiroshi Matsubara
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Takuji Kawamoto
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Takahide Fukuyama
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
| | - Ilhyong Ryu
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan 300, ROC
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22
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Abstract
The alkylation of enolates is one of the backbones of ketone chemistry, yet in practice it suffers from numerous limitations due to problems of regiochemistry (including O- versus C-alkylation), multiple alkylations, self-condensation, competing elimination, and incompatibility with many polar groups that have to be protected. Over the years, various solutions have been devised to overcome these difficulties, such as the employment of auxiliary ester or sulfone groups to modify the p Ka of the enolizable hydrogens, the passage by the corresponding hydrazones, the use of transition-metal-catalyzed redox systems to formally alkylate ketones with alcohols, etc. Most of these hurdles disappear upon switching to α-ketonyl radicals. Radicals are tolerant of most polar functions, and radical additions to flat sp2 centers are generally easier to accomplish than enolate substitution at tetrahedral sp3 carbons. The main stumbling block, however, has been a lack of generally applicable methods for the generation and intermolecular capture of α-ketonyl radicals. We have found over the past years that the degenerative exchange of xanthates represents in many ways an ideal solution to this problem. It overcomes essentially all of the difficulties faced by other radical processes because of its unique ability to reversibly store reactive radicals in a dormant, nonreactive form. The lifetime of the radicals can therefore be significantly enhanced, even in the concentrated medium needed for bimolecular additions, while at the same time regulating their absolute and relative concentrations. The ability to perform intermolecular additions to highly functionalized alkene partners opens up numerous possibilities for rapid and convergent access to complex structures. Of particular importance is the elaboration of ketones that are prone to self-condensation, such trifluoroacetone, and of base-sensitive ketones, such as chloro- and dichloroacetone, since the products can be used for the synthesis of a myriad fluorinated and heteroaromatic compounds of relevance to medicinal chemistry and agrochemistry. The formal distal dialkylation of ketones, also of utmost synthetic interest, is readily accomplished, allowing convenient access to a wide array of useful ketone building blocks. Cascade processes can be implemented and, in alliance with powerful classical reactions (aldol, alkylative Birch reductions, etc.), furnish a quick route to complex polycyclic scaffolds. Furthermore, the presence of the xanthate group in the adducts can be exploited to obtain a variety of arenes and heteroarenes, such as pyrroles, thiophenes, naphthalenes, and pyridines, as well as enones, dienes, and cyclopropanes. Last but not least, the reagents and most of the starting materials are exceedingly cheap, and the reactions are safe and easy to scale up.
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Affiliation(s)
- Samir Z. Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652 Ecole Polytechnique, 91128 Palaiseau Cedex, France
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23
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Hayashi H, Kaga A, Wang B, Gagosz F, Chiba S. Use of a benzyl ether as a traceless hydrogen donor in the anti-Markovnikov hydrofunctionalization of alkenes with xanthates. Chem Commun (Camb) 2018; 54:7535-7538. [PMID: 29926014 DOI: 10.1039/c8cc02971g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A new protocol for the anti-Markovnikov hydrofunctionalization of alkenyl alcohol O-Bn ethers was developed using xanthates as functionalizing agents in the presence of lauroyl peroxide as a radical initiator and a stoichiometric oxidant. The benzyl group serves as a traceless hydrogen donor in the remote radical hydrogen atom transfer event during the process.
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Affiliation(s)
- Hirohito Hayashi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
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Wang QQ, Wang ZX, Zhang XY, Fan XS. Microwave-Promoted Metal-Free α-Alkylation of Ketones with Cycloalkanes through Cross-Coupling of C(sp3
)−H Bonds. ASIAN J ORG CHEM 2017. [DOI: 10.1002/ajoc.201700256] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Qian-Qian Wang
- School of Chemistry and Chemical Engineering; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals; Henan Key Laboratory of Organic Functional Molecule and Drug Innovation; Key Laboratory of Green Chemical Media and Reactions; Ministry of Education, Henan Normal University; Xinxiang Henan 453007 China
- School of Pharmacy; Xinxiang Medical University; Xinxiang Henan 453003 China
| | - Zhang-Xin Wang
- School of Chemistry and Chemical Engineering; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals; Henan Key Laboratory of Organic Functional Molecule and Drug Innovation; Key Laboratory of Green Chemical Media and Reactions; Ministry of Education, Henan Normal University; Xinxiang Henan 453007 China
| | - Xin-Ying Zhang
- School of Chemistry and Chemical Engineering; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals; Henan Key Laboratory of Organic Functional Molecule and Drug Innovation; Key Laboratory of Green Chemical Media and Reactions; Ministry of Education, Henan Normal University; Xinxiang Henan 453007 China
| | - Xue-Sen Fan
- School of Chemistry and Chemical Engineering; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals; Henan Key Laboratory of Organic Functional Molecule and Drug Innovation; Key Laboratory of Green Chemical Media and Reactions; Ministry of Education, Henan Normal University; Xinxiang Henan 453007 China
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25
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Quiclet-Sire B, Zard SZ. Some aspects of radical cascade and relay reactions. Proc Math Phys Eng Sci 2017; 473:20160859. [PMID: 28484329 PMCID: PMC5415689 DOI: 10.1098/rspa.2016.0859] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 03/02/2017] [Indexed: 01/28/2023] Open
Abstract
The ability to create carbon-carbon bonds is at the heart of organic synthesis. Radical processes are particularly apt at creating such bonds, especially in cascade or relay sequences where more than one bond is formed, allowing for a rapid assembly of complex structures. In the present brief overview, examples taken from the authors' laboratory will serve to illustrate the strategic impact of radical-based approaches on synthetic planning. Transformations involving nitrogen-centred radicals, electron transfer from metallic nickel and the reversible degenerative exchange of xanthates will be presented and discussed. The last method has proved to be a particularly powerful tool for the intermolecular creation of carbon-carbon bonds by radical additions even to unactivated alkenes. Various functional groups can be brought into the same molecule in a convergent manner and made to react together in order to further increase the structural complexity. One important benefit of this chemistry is the so-called RAFT/MADIX technology for the manufacture of block copolymers of almost any desired architecture.
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Affiliation(s)
| | - Samir Z. Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole Polytechnique, 91128 Palaiseau, France
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27
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Yan M, Lo JC, Edwards JT, Baran PS. Radicals: Reactive Intermediates with Translational Potential. J Am Chem Soc 2016; 138:12692-12714. [PMID: 27631602 PMCID: PMC5054485 DOI: 10.1021/jacs.6b08856] [Citation(s) in RCA: 667] [Impact Index Per Article: 83.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Indexed: 02/08/2023]
Abstract
This Perspective illustrates the defining characteristics of free radical chemistry, beginning with its rich and storied history. Studies from our laboratory are discussed along with recent developments emanating from others in this burgeoning area. The practicality and chemoselectivity of radical reactions enable rapid access to molecules of relevance to drug discovery, agrochemistry, material science, and other disciplines. Thus, these reactive intermediates possess inherent translational potential, as they can be widely used to expedite scientific endeavors for the betterment of humankind.
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Affiliation(s)
- Ming Yan
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Julian C. Lo
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Jacob T. Edwards
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Phil S. Baran
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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28
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Pan C, Chen R, Shao W, Yu JT. Metal-free radical addition/cyclization of alkynoates with xanthates towards 3-(β-carbonyl)coumarins. Org Biomol Chem 2016; 14:9033-9. [DOI: 10.1039/c6ob01732k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dilauroyl peroxide-promoted radical carboannulation of alkynoates with xanthates was developed, affording 4-aryl-3-(β-carbonyl) coumarins in moderate to good yields.
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Affiliation(s)
- Changduo Pan
- School of Chemistry & Environmental Engineering
- Jiangsu University of Technology
- Changzhou 213001
- P. R. China
- School of Petrochemical Engineering
| | - Rongzhen Chen
- School of Chemistry & Environmental Engineering
- Jiangsu University of Technology
- Changzhou 213001
- P. R. China
- School of Petrochemical Engineering
| | - Weile Shao
- School of Chemistry & Environmental Engineering
- Jiangsu University of Technology
- Changzhou 213001
- P. R. China
| | - Jin-Tao Yu
- School of Petrochemical Engineering
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology
- Changzhou University
- Changzhou 213164
- P. R. China
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