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Murray PD, Cox JH, Chiappini ND, Roos CB, McLoughlin EA, Hejna BG, Nguyen ST, Ripberger HH, Ganley JM, Tsui E, Shin NY, Koronkiewicz B, Qiu G, Knowles RR. Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis. Chem Rev 2022; 122:2017-2291. [PMID: 34813277 PMCID: PMC8796287 DOI: 10.1021/acs.chemrev.1c00374] [Citation(s) in RCA: 172] [Impact Index Per Article: 86.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Indexed: 12/16/2022]
Abstract
We present here a review of the photochemical and electrochemical applications of multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms in which both an electron and a proton are exchanged together, often in a concerted elementary step. As such, MS-PCET can function as a non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from a wide variety of common organic functional groups. We present an introduction to MS-PCET and a practitioner's guide to reaction design, with an emphasis on the unique energetic and selectivity features that are characteristic of this reaction class. We then present chapters on oxidative N-H, O-H, S-H, and C-H bond homolysis methods, for the generation of the corresponding neutral radical species. Then, chapters for reductive PCET activations involving carbonyl, imine, other X═Y π-systems, and heteroarenes, where neutral ketyl, α-amino, and heteroarene-derived radicals can be generated. Finally, we present chapters on the applications of MS-PCET in asymmetric catalysis and in materials and device applications. Within each chapter, we subdivide by the functional group undergoing homolysis, and thereafter by the type of transformation being promoted. Methods published prior to the end of December 2020 are presented.
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Affiliation(s)
- Philip
R. D. Murray
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - James H. Cox
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Nicholas D. Chiappini
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Casey B. Roos
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | | | - Benjamin G. Hejna
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Suong T. Nguyen
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Hunter H. Ripberger
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Jacob M. Ganley
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Elaine Tsui
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Nick Y. Shin
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Brian Koronkiewicz
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Guanqi Qiu
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
| | - Robert R. Knowles
- Department of Chemistry, Princeton
University, Princeton, New Jersey 08544, United States
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2
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Bume DD, Harry SA, Lectka T, Pitts CR. Catalyzed and Promoted Aliphatic Fluorination. J Org Chem 2018; 83:8803-8814. [PMID: 29894188 DOI: 10.1021/acs.joc.8b00982] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the last six years, the direct functionalization of aliphatic C-H (and C-C) bonds through user-friendly, radical-based fluorination reactions has emerged as an exciting research area in fluorine chemistry. Considering the historical narratives about the challenges of developing practical radical fluorination in organic frameworks, notable advancements in controlling both reactivity and selectivity have been achieved during this time. As one of the participants in the field, herein, we a provide brief account of research efforts in our laboratory from the initial discovery of radical monofluorination on unactivated C-H bonds in 2012 to more useful strategies to install fluorine on biologically relevant molecules through directed fluorination methods. In addition, accompanying mechanistic studies that have helped guide reaction design are highlighted in context.
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Affiliation(s)
| | | | | | - Cody Ross Pitts
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 2 , 8093 Zürich , Switzerland
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3
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Fustero S, Sedgwick DM, Román R, Barrio P. Recent advances in the synthesis of functionalised monofluorinated compounds. Chem Commun (Camb) 2018; 54:9706-9725. [DOI: 10.1039/c8cc05181j] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Over the past few years, we have tackled the synthesis of interesting monofluorinated organic molecules, such as: dihydronaphthalene derivatives, β-fluoro sulfones and related carbonyl compounds, fluorohydrins and allylic alcohols.
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Affiliation(s)
- Santos Fustero
- Departamento de Química Orgánica
- Universidad de Valencia
- E-46100 Burjassot
- Spain
- Laboratorio de Moléculas Orgánicas
| | - Daniel M. Sedgwick
- Departamento de Química Orgánica
- Universidad de Valencia
- E-46100 Burjassot
- Spain
- Laboratorio de Moléculas Orgánicas
| | - Raquel Román
- Laboratorio de Moléculas Orgánicas
- Centro de Investigación Príncipe Felipe
- E-46012 Valencia
- Spain
| | - Pablo Barrio
- Departamento de Química Orgánica
- Universidad de Valencia
- E-46100 Burjassot
- Spain
- Laboratorio de Moléculas Orgánicas
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4
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Lantaño B, Postigo A. Radical fluorination reactions by thermal and photoinduced methods. Org Biomol Chem 2017; 15:9954-9973. [DOI: 10.1039/c7ob02402a] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Radical fluorination reactions of aliphatic Csp3 and Csp2 atoms, decarboxylative fluorination, and fluorination of (hetero)aromatics can be accomplished with electrophilic fluorinating reagents such as Selectfluor and NFSI.
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Affiliation(s)
- Beatriz Lantaño
- Universidad de Buenos Aires
- Facultad de Farmacia y Bioquímica
- Departamento de Química Orgánica-Conicet-Buenos Aires
- Argentina
- Ciudad de Buenos Aires
| | - Al Postigo
- Universidad de Buenos Aires
- Facultad de Farmacia y Bioquímica
- Departamento de Química Orgánica-Conicet-Buenos Aires
- Argentina
- Ciudad de Buenos Aires
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Field MJ, Sinha S, Warren JJ. Photochemical proton-coupled C–H activation: an example using aliphatic fluorination. Phys Chem Chem Phys 2016; 18:30907-30911. [DOI: 10.1039/c6cp06418c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Excited state organic photosensitizers are investigated in the context of their ability to activate CH bonds via outer sphere electron transfer or via proton-coupled electron transfer.
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Affiliation(s)
| | - Soumalya Sinha
- Department of Chemistry
- Simon Fraser University
- Burnaby
- Canada
| | - Jeffrey J. Warren
- Department of Chemistry
- Simon Fraser University
- Burnaby
- Canada
- Canadian Institute for Applied Research
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6
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Bloom S, Bume DD, Pitts CR, Lectka T. Site-Selective Approach to β-Fluorination: Photocatalyzed Ring Opening of Cyclopropanols. Chemistry 2015; 21:8060-3. [DOI: 10.1002/chem.201501081] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Indexed: 12/14/2022]
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7
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Cyr D, Das P. Quenching of diphenylmethyl radical fluorescence by cyanoaromatics and phenols. RESEARCH ON CHEMICAL INTERMEDIATES 2015. [DOI: 10.1007/s11164-014-1914-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bloom S, McCann M, Lectka T. Photocatalyzed benzylic fluorination: shedding "light" on the involvement of electron transfer. Org Lett 2014; 16:6338-41. [PMID: 25493423 DOI: 10.1021/ol503094m] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The photocatalyzed oxidation of benzylic compounds by 1,2,4,5-tetracyanobenzene (TCB) in the presence of Selectfluor provides a synthetically efficient route to electron deficient, less substituted, and otherwise inaccessible benzylic fluorides. The virtue of this system is multifold: it is metal-free and mild, and the reagents are inexpensive. Mechanistically, the data suggest the intimate formation of intermediate radical cations in the key radical forming step, as opposed to a concerted hydrogen atom transfer process.
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Affiliation(s)
- Steven Bloom
- Contribution from the Department of Chemistry, New Chemistry Building, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
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Cyr D, Das P. Kinetics of C–C and C–H Bond Cleavage in Phenyl Alkane Radical Cations Generated by Photoinduced Electron Transfer. J Phys Chem A 2014; 118:11155-67. [DOI: 10.1021/jp508556z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Douglas Cyr
- Physical
Sciences Department, Cameron University, Lawton, Oklahoma 73505, United States
| | - Paritosh Das
- Physical
Sciences Department, Cameron University, Lawton, Oklahoma 73505, United States
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Tang J, Yue JJ, Tao FF, Grampp G, Wang BX, Li F, Liang XZ, Shen YM, Xu JH. A Three-Component Reaction by Photoinduced Electron Transfer Mechanism with N-Protected Pyrroles as Neutral Carbon Nucleophiles. J Org Chem 2014; 79:7572-82. [DOI: 10.1021/jo5013114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jian Tang
- School
of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing 312000, China
- Jiangsu
Key Laboratory of Biofunctional Materials, School of Chemistry and
Materials Science, Nanjing Normal University, Nanjing 210097, China
| | - Jia-Jun Yue
- Institute
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Fei-Fei Tao
- School
of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing 312000, China
| | - Guenter Grampp
- Physical
and Theoretical Chemistry, Graz University of Technology, Stremayrgasse
9/Z2, A-8010 Graz, Austria
| | - Bing-Xiang Wang
- Jiangsu
Key Laboratory of Biofunctional Materials, School of Chemistry and
Materials Science, Nanjing Normal University, Nanjing 210097, China
| | - Fang Li
- School
of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing 312000, China
| | - Xue-Zheng Liang
- School
of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing 312000, China
| | - Yong-Miao Shen
- School
of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing 312000, China
| | - Jian-Hua Xu
- Institute
of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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11
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Abstract
We disclose a new approach to the catalysis of alkane fluorination employing ultraviolet light and a photosensitizer, 1,2,4,5-tetracyanobenzene (TCB).
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Affiliation(s)
- Steven Bloom
- Department of Chemistry
- Johns Hopkins University
- Baltimore, USA
| | | | - Thomas Lectka
- Department of Chemistry
- Johns Hopkins University
- Baltimore, USA
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12
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Fagnoni M, Protti S, Ravelli D, Albini A. Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes. Beilstein J Org Chem 2013; 9:800-8. [PMID: 23766793 PMCID: PMC3678633 DOI: 10.3762/bjoc.9.91] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 04/03/2013] [Indexed: 11/23/2022] Open
Abstract
Steady-state irradiation in neat acetonitrile of some aromatic nitriles, imides and esters (10(-5)-10(-3) M solution) in the presence of tertiary amines allowed the accumulation of the corresponding radical anions, up to quantitative yield for polysubstituted benzenes and partially with naphthalene and anthracene derivatives. The condition for such an accumulation was that the donor radical cation underwent further evolution that precluded back electron transfer and any chemical reaction with the radical anion. In fact, no accumulation occurred with 1,4-diazabicyclo[2.2.2]octane (DABCO), for which this condition is not possible. The radical anions were produced from benzene polyesters too, but decomposition began early. Ipso substitution was one of the paths with secondary amines and the only reaction with tetrabutylstannane. The results fully support the previously proposed mechanism for electron transfer (ET) mediated photochemical alkylation of aromatic acceptors via radical ions and radical intermediates.
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Affiliation(s)
- Maurizio Fagnoni
- PhotoGreen Lab, Department of Chemistry, University of Pavia, V. Le Taramelli 12, 27100 Pavia, Italy
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