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Ueno K, Ushimaru R, Abe I. Photoinduced Reductive Dehalogenation of Phenacyl Bromides with Pyridoxal 5'-Phosphate. Chem Pharm Bull (Tokyo) 2023; 71:675-677. [PMID: 37394629 DOI: 10.1248/cpb.c23-00434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
We describe the photoinduced reductive debromination of phenacyl bromides using pyridoxal 5'-phosphate (PLP). The reaction requires irradiation with cyan or blue light in an anaerobic atmosphere. Mechanistic analysis reveals the formation of the phenacyl radical as an intermediate in the reaction, implying a single electron transfer to phenacyl bromides from a PLP-derived species resulting from excitation by illumination.
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Affiliation(s)
- Koki Ueno
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
| | - Richiro Ushimaru
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
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2
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Pavlovska T, Král Lesný D, Svobodová E, Hoskovcová I, Archipowa N, Kutta RJ, Cibulka R. Tuning Deazaflavins Towards Highly Potent Reducing Photocatalysts Guided by Mechanistic Understanding – Enhancement of the Key Step by the Internal Heavy Atom Effect. Chemistry 2022; 28:e202200768. [PMID: 35538649 PMCID: PMC9541856 DOI: 10.1002/chem.202200768] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Indexed: 11/11/2022]
Abstract
Deazaflavins are well suited for reductive chemistry acting via a consecutive photo‐induced electron transfer, in which their triplet state and semiquinone – the latter is formed from the former after electron transfer from a sacrificial electron donor – are key intermediates. Guided by mechanistic investigations aiming to increase intersystem crossing by the internal heavy atom effect and optimising the concentration conditions to avoid unproductive excited singlet reactions, we synthesised 5‐aryldeazaflavins with Br or Cl substituents on different structural positions via a three‐component reaction. Bromination of the deazaisoalloxazine core leads to almost 100 % triplet yield but causes photo‐instability and enhances unproductive side reactions. Bromine on the 5‐phenyl group in ortho position does not affect the photostability, increases the triplet yield, and allows its efficient usage in the photocatalytic dehalogenation of bromo‐ and chloroarenes with electron‐donating methoxy and alkyl groups even under aerobic conditions. Reductive powers comparable to lithium are achieved.
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Affiliation(s)
- Tetiana Pavlovska
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - David Král Lesný
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Eva Svobodová
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Irena Hoskovcová
- Department of Inorganic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Nataliya Archipowa
- Institute for Biophysics and Physical Biochemistry University of Regensburg D-93053 Regensburg Germany
| | - Roger Jan Kutta
- Institute of Physical and Theoretical Chemistry University of Regensburg D-93053 Regensburg Germany
| | - Radek Cibulka
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
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3
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Pavanello A, Miranda MA, Marin ML. Organic photoredox catalysts for wastewater remediation: Beyond the established advanced oxidation processes. CHEMICAL ENGINEERING JOURNAL ADVANCES 2022. [DOI: 10.1016/j.ceja.2022.100296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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4
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Pavanello A, Gomez-Mendoza M, de la Peña O'Shea VA, Miranda MA, Marin ML. Degradation of Benzotriazole UV-stabilizers in the presence of organic photosensitizers and visible light: A time-resolved mechanistic study. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 230:112444. [PMID: 35429826 DOI: 10.1016/j.jphotobiol.2022.112444] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 03/16/2022] [Accepted: 04/05/2022] [Indexed: 12/28/2022]
Abstract
Benzotriazole UV-stabilizers (BUVSs) are commonly used in industry as solar filters, due to their strong UV light absorption. Because of their extended usage, environmental contamination of waters due to BUVSs constitutes a growing concern. Direct photodegradation of BUVSs is not efficient due to their intrinsic thermal pathways to release the absorbed light. Nevertheless, their abatement in natural environments could be assisted by chromophoric dissolved organic matter. Among the BUVSs, three representative candidates were selected, UV-326, UV-327 and UV-328, to demonstrate the potential of Riboflavin (RF) as a natural visible-light absorbing photocatalyst for the abatement of these recalcitrant pollutants under reductive conditions. The use of visible light and DABCO, as a model sacrificial electron donor, generates the radical anion RFTA.-. This key species reacts with the solar filters, achieving their reductive abatement from the medium. Moreover, the participation of every potential reactive species has been investigated by photophysical techniques, together with determination of the quenching rate constant for every reaction pathway. Consequently, evidence supported the main role of the reductive photodegradation pathway, being RFTA.- the key species in the abatement of BUVSs.
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Affiliation(s)
- Alice Pavanello
- Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avda. de los Naranjos s/n, E-46022, Valencia, Spain
| | - Miguel Gomez-Mendoza
- Photoactivated Processes Unit, IMDEA Energy Institute, Technological Park of Móstoles, Avda. Ramón de la Sagra 3, 28935 Madrid, Spain
| | - Víctor A de la Peña O'Shea
- Photoactivated Processes Unit, IMDEA Energy Institute, Technological Park of Móstoles, Avda. Ramón de la Sagra 3, 28935 Madrid, Spain
| | - Miguel A Miranda
- Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avda. de los Naranjos s/n, E-46022, Valencia, Spain
| | - M Luisa Marin
- Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avda. de los Naranjos s/n, E-46022, Valencia, Spain.
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5
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Red edge effect and chromoselective photocatalysis with amorphous covalent triazine-based frameworks. Nat Commun 2022; 13:2171. [PMID: 35449208 PMCID: PMC9023581 DOI: 10.1038/s41467-022-29781-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 03/14/2022] [Indexed: 11/08/2022] Open
Abstract
Chromoselective photocatalysis offers an intriguing opportunity to enable a specific reaction pathway out of a potentially possible multiplicity for a given substrate by using a sensitizer that converts the energy of incident photon into the redox potential of the corresponding magnitude. Several sensitizers possessing different discrete redox potentials (high/low) upon excitation with photons of specific wavelength (short/long) have been reported. Herein, we report design of molecular structures of two-dimensional amorphous covalent triazine-based frameworks (CTFs) possessing intraband states close to the valence band with strong red edge effect (REE). REE enables generation of a continuum of excited sites characterized by their own redox potentials, with the magnitude proportional to the wavelength of incident photons. Separation of charge carriers in such materials depends strongly on the wavelength of incident light and is the primary parameter that defines efficacy of the materials in photocatalytic bromination of electron rich aromatic compounds. In dual Ni-photocatalysis, excitation of electrons from the intraband states to the conduction band of the CTF with 625 nm photons enables selective formation of C‒N cross-coupling products from arylhalides and pyrrolidine, while an undesirable dehalogenation process is completely suppressed.
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Spielvogel EH, Stevenson BG, Stringer MJ, Hu Y, Fredin LA, Swierk JR. Insights into the Mechanism of an Allylic Arylation Reaction via Photoredox-Coupled Hydrogen Atom Transfer. J Org Chem 2021; 87:223-230. [PMID: 34882427 DOI: 10.1021/acs.joc.1c02235] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Despite widespread use as a synthetic method, the precise mechanism and kinetics of photoredox coupled hydrogen atom transfer (HAT) reactions remain poorly understood. This results from a lack of detailed kinetic information as well as the identification of side reactions and products. In this report, a mechanistic study of a prototypical tandem photoredox/HAT reaction coupling cyclohexene and 1,4-dicyanobenzene (DCB) using an Ir(ppy)3 photocatalyst and thiol HAT catalyst is reported. Through a combination of electrochemical, photochemical, and spectroscopic measurements, key unproductive pathways and side products are identified and rate constants for the main chemical steps are extracted. The reaction quantum yield was found to decline rapidly over the course of the reaction. An unreported cyanohydrin side product was identified and thought to play a key role as a proton acceptor in the reaction. Transient absorption spectroscopy (TAS) and quantum chemical calculations suggested a reaction mechanism that involves radical addition of the nucleophilic DCB radical anion to cyclohexene, with cooperative HAT occurring as the final step to regenerate the alkene. Kinetic modeling of the reaction, using rate constants derived from TAS, demonstrates that the efficiency of the reaction is limited by parasitic absorption and unproductive quenching between excited Ir(ppy)3 and the cyanohydrin photoproduct.
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Affiliation(s)
- Ethan H Spielvogel
- Department of Chemistry, State University of New York at Binghamton, Vestal, New York 13850, United States
| | - Bernard G Stevenson
- Department of Chemistry, State University of New York at Binghamton, Vestal, New York 13850, United States
| | - Michael J Stringer
- Department of Chemistry, State University of New York at Binghamton, Vestal, New York 13850, United States
| | - Yue Hu
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Lisa A Fredin
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - John R Swierk
- Department of Chemistry, State University of New York at Binghamton, Vestal, New York 13850, United States
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7
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Materna KL, Hammarström L. Photoredox Catalysis Using Heterogenized Iridium Complexes*. Chemistry 2021; 27:16966-16977. [PMID: 34137473 PMCID: PMC9292873 DOI: 10.1002/chem.202101651] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Indexed: 12/27/2022]
Abstract
Heterogenized photoredox catalysts provide a path for sustainable chemical synthesis using highly tunable, reusable constructs. Here, heterogenized iridium complexes as photoredox catalysts were assembled via covalent attachment to metal oxide surfaces (ITO, ZrO2 , Al2 O3 ) in thin film or nanopowder constructs. The goal was to understand which materials provided the most promising constructs for catalysis. To do this, reductive dehalogenation of bromoacetophenone to acetophenone was studied as a test reaction for system optimization. All catalyst constructs produced acetophenone with high conversions and yields with the fastest reactions complete in fifteen minutes using Al2 O3 supports. The nanopowder catalysts resulted in faster and more efficient catalysis, while the thin film catalysts were more robust and easily reused. Importantly, the thin film constructs show promise for future photoelectrochemical and electrochemical photoredox setups. Finally, all catalysts were reusable 2-3 times, performing at least 1000 turnovers (Al2 O3 ), demonstrating that heterogenized catalysts are a sustainable catalyst alternative.
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Affiliation(s)
- Kelly L Materna
- Department of Chemistry-Ångström Laboratories, Uppsala University, Box 523, SE, 75120, Uppsala, Sweden
| | - Leif Hammarström
- Department of Chemistry-Ångström Laboratories, Uppsala University, Box 523, SE, 75120, Uppsala, Sweden
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8
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Abstract
The fields of C-H functionalization and photoredox catalysis have garnered enormous interest and utility in the past several decades. Many different scientific disciplines have relied on C-H functionalization and photoredox strategies including natural product synthesis, drug discovery, radiolabeling, bioconjugation, materials, and fine chemical synthesis. In this Review, we highlight the use of photoredox catalysis in C-H functionalization reactions. We separate the review into inorganic/organometallic photoredox catalysts and organic-based photoredox catalytic systems. Further subdivision by reaction class-either sp2 or sp3 C-H functionalization-lends perspective and tactical strategies for use of these methods in synthetic applications.
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Affiliation(s)
- Natalie Holmberg-Douglas
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - David A Nicewicz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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Bell JD, Murphy JA. Recent advances in visible light-activated radical coupling reactions triggered by (i) ruthenium, (ii) iridium and (iii) organic photoredox agents. Chem Soc Rev 2021; 50:9540-9685. [PMID: 34309610 DOI: 10.1039/d1cs00311a] [Citation(s) in RCA: 134] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Photoredox chemistry with organic or transition metal agents has been reviewed in earlier years, but such is the pace of progress that we will overlap very little with earlier comprehensive reviews. This review first presents an overview of the area of research and then examines recent examples of C-C, C-N, C-O and C-S bond formations via radical intermediates with transition metal and organic radical promoters. Recent successes with Birch reductions are also included. The transition metal chemistry will be restricted to photocatalysts based on the most widely used metals, Ru and Ir, but includes coupling chemistries that take advantage of low-valent nickel, or occasionally copper, complexes to process the radicals that are formed. Our focus is on developments in the past 10 years (2011-2021). This period has also seen great advances in the chemistry of organic photoredox reagents and the review covers this area. The review is intended to present highlights and is not comprehensive.
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Affiliation(s)
- Jonathan D Bell
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
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10
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Pavanello A, Fabbri D, Calza P, Battiston D, Miranda MA, Marin ML. Photocatalytic degradation of drugs in water mediated by acetylated riboflavin and visible light: A mechanistic study. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2021; 221:112250. [PMID: 34243022 DOI: 10.1016/j.jphotobiol.2021.112250] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 06/02/2021] [Accepted: 06/26/2021] [Indexed: 10/21/2022]
Abstract
There is a current concern, among the scientific community, on the pollutants classified as "persistent organic pollutants (POPs)". Pharmaceuticals and personal care products (PPCPs) belong to this family of contaminants; therefore, it is necessary to find more efficient techniques able to achieve their removal from the environment. This study focuses on two different pharmaceuticals: carbamazepine and atenolol, chosen for their widespread use and their different chemical and medical properties. In this work, an organic dye, acetylated riboflavin, has been used in combination with visible light to achieve the photodegradation of these two POPs in <2 h. Moreover, photophysical experiments demonstrated the involvement of the singlet and triplet excited states of acetylated riboflavin and the generated singlet oxygen in the removal of these drugs. Besides, a detailed UFLC-MS-MS analysis of the photoproducts confirmed the oxidation of the drugs. Finally, a plausible mechanism has been postulated.
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Affiliation(s)
- Alice Pavanello
- Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, E-46022 Valencia, Spain
| | - Debora Fabbri
- Dipartimento di Chimica, Università di Torino, via P. Giuria 5, 10125 Torino, Italy
| | - Paola Calza
- Dipartimento di Chimica, Università di Torino, via P. Giuria 5, 10125 Torino, Italy
| | - Debora Battiston
- Dipartimento di Chimica, Università di Torino, via P. Giuria 5, 10125 Torino, Italy
| | - Miguel A Miranda
- Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, E-46022 Valencia, Spain
| | - M Luisa Marin
- Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, E-46022 Valencia, Spain.
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11
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Stevenson BG, Spielvogel EH, Loiaconi EA, Wambua VM, Nakhamiyayev RV, Swierk JR. Mechanistic Investigations of an α-Aminoarylation Photoredox Reaction. J Am Chem Soc 2021; 143:8878-8885. [PMID: 34077202 DOI: 10.1021/jacs.1c03693] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
While photoredox catalysis continues to transform modern synthetic chemistry, detailed mechanistic studies involving direct observation of reaction intermediates and rate constants are rare. By use of a combination of steady state photochemical measurements, transient laser spectroscopy, and electrochemical methods, an α-aminoarylation mechanism that is the inspiration for a large number of photoredox reactions was rigorously characterized. Despite high product yields, the external quantum yield (QY) of the reaction remained low (15-30%). By use of transient absorption spectroscopy, productive and unproductive reaction pathways were identified and rate constants assigned to develop a comprehensive mechanistic picture of the reaction. The role of the cyanoarene, 1,4-dicyanobenzne, was found to be unexpectedly complex, functioning both as initial proton acceptor in the reaction and as a neutral stabilizer for the 1,4-dicyanobenzene radical anion. Finally, kinetic modeling was utilized to analyze the reaction at an unprecedented level of understanding. This modeling demonstrated that the reaction is limited not by the kinetics of the individual steps but instead by scattering losses and parasitic absorption by a photochemically inactive donor-acceptor complex.
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Affiliation(s)
- Bernard G Stevenson
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Ethan H Spielvogel
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Emily A Loiaconi
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Victor Mulwa Wambua
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Roman V Nakhamiyayev
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - John R Swierk
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
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12
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Martínez-Haya R, Heredia AA, Castro-Godoy WD, Schmidt LC, Marin ML, Argüello JE. Mechanistic Insight into the Light-Triggered CuAAC Reaction: Does Any of the Photocatalyst Go? J Org Chem 2021; 86:5832-5844. [PMID: 33825466 DOI: 10.1021/acs.joc.1c00272] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The attainment of transition-metal catalysis and photoredox catalysis has represented a great challenge over the last years. Herein, we have been able to merge both catalytic processes into what we have called "the light-triggered CuAAC reaction". Particularly, the CuAAC reaction reveals opposite outcomes depending on the nature of the photocatalyst (eosin Y disodium salt and riboflavin tetraacetate) and additives (DABCO, Et3N, and NaN3) employed. To get a better insight into the operating processes, steady-state, time-resolved emission, and laser flash photolysis experiments have been performed to determine reactivity and kinetic data. These results, in agreement with thermodynamic estimations based on reported data, support the proposed mechanisms. While for eosin Y (EY), Cu(II) was reduced by its triplet excited state; for riboflavin tetraacetate (RFTA), mainly triplet excited RFTA state photoreductions by electron donors as additives are mandatory, affording RFTA•- (from DABCO and NaN3) or RFTAH• (from Et3N). Subsequently, these species are responsible for the reduction of Cu(II). For both photocatalysts, photogenerated Cu(I) finally renders 1,2,3-triazole as the final product. The determined kinetic rate constants allowed postulating plausible mechanisms in both cases, bringing to light the importance of kinetic studies to achieve a strong understanding of photoredox processes.
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Affiliation(s)
- Rebeca Martínez-Haya
- Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avenida de los Naranjos s/n, 46022 Valencia, Spain
| | - Adrián A Heredia
- INFIQC-CONICET-UNC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Willber D Castro-Godoy
- Departamento de Química, Física y Matemática, Facultad de Química y Farmacia, Universidad de El Salvador, Final Av. de Mártires y Héroes del 30 de Julio, San Salvador 1101, El Salvador
| | - Luciana C Schmidt
- INFIQC-CONICET-UNC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - M Luisa Marin
- Instituto de Tecnología Química, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avenida de los Naranjos s/n, 46022 Valencia, Spain
| | - Juan E Argüello
- INFIQC-CONICET-UNC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
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13
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Patel RI, Sharma S, Sharma A. Cyanation: a photochemical approach and applications in organic synthesis. Org Chem Front 2021. [DOI: 10.1039/d1qo00162k] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This review summarises the photocatalytic cyanation strategies to construct C(sp2)–CN, C(sp3)–CN and X–CN (X = N, S) bonds.
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Affiliation(s)
- Roshan I. Patel
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
| | - Shivani Sharma
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
| | - Anuj Sharma
- Department of Chemistry
- Indian Institute of Technology Roorkee
- Roorkee-247667
- India
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14
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Chen Y, Ni N, Cheng D, Xu X. The coupling of alkylboronic acids with α-(trifluoromethyl)styrenes by Lewis base/photoredox dual catalysis. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2020.152425] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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15
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Amos SGE, Garreau M, Buzzetti L, Waser J. Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis. Beilstein J Org Chem 2020; 16:1163-1187. [PMID: 32550931 PMCID: PMC7277890 DOI: 10.3762/bjoc.16.103] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 05/11/2020] [Indexed: 12/11/2022] Open
Abstract
Organic dyes have emerged as a reliable class of photoredox catalysts. Their great structural variety combined with the easy fine-tuning of their electronic properties has unlocked new possibilities for the generation of reactive intermediates. In this review, we provide an overview of the available approaches to access reactive intermediates that employ organophotocatalysis. Our contribution is not a comprehensive description of the work in the area but rather focuses on key concepts, accompanied by a few selected illustrative examples. The review is organized along the type of reactive intermediates formed in the reaction, including C(sp3) and C(sp 2 ) carbon-, nitrogen-, oxygen-, and sulfur-centered radicals, open-shell charged species, and sensitized organic compounds.
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Affiliation(s)
- Stephanie G E Amos
- Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306 1015 Lausanne, Switzerland
| | - Marion Garreau
- Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306 1015 Lausanne, Switzerland
| | - Luca Buzzetti
- Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306 1015 Lausanne, Switzerland
| | - Jerome Waser
- Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306 1015 Lausanne, Switzerland
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16
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Arakawa Y, Mihara T, Fujii H, Minagawa K, Imada Y. An uncommon use of irradiated flavins: Brønsted acid catalysis. Chem Commun (Camb) 2020; 56:5661-5664. [PMID: 32315001 DOI: 10.1039/d0cc01960g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We present that thioacetalization of aldehydes can be induced by blue light irradiation in the presence of a catalytic amount of riboflavin tetraacetate (RFTA) under aerobic conditions. Several control experiments have suggested that the reaction is more likely to be catalyzed by acidic species generated in situ upon light irradiation. We have proposed that single electron transfer from a thiol (RSH) to the excited state of RFTA can take place to give a one-electron oxidized thiol (RSH+˙) and the one-electron reduced RFTA (RFTA-˙), which can be trapped by molecular oxygen to be stabilized as Brønsted acids including the protonated RFTA-˙ (RFTAH˙). Finally, we have demonstrated that such acidic species can be prepared in advance as a solution and used as Brønsted acid catalysts for not only thioacetalization but also Mannich-type reactions.
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Affiliation(s)
- Yukihiro Arakawa
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.
| | - Tomohiro Mihara
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.
| | - Hiroki Fujii
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.
| | - Keiji Minagawa
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan. and Institute of Liberal Arts and Sciences, Tokushima University, Minamijosanjima, Tokushima 770-8502, Japan
| | - Yasushi Imada
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.
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Hasegawa E, Yoshioka N, Tanaka T, Nakaminato T, Oomori K, Ikoma T, Iwamoto H, Wakamatsu K. Sterically Regulated α-Oxygenation of α-Bromocarbonyl Compounds Promoted Using 2-Aryl-1,3-dimethylbenzimidazolines and Air. ACS OMEGA 2020; 5:7651-7665. [PMID: 32280909 PMCID: PMC7144160 DOI: 10.1021/acsomega.0c00509] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 03/05/2020] [Indexed: 05/08/2023]
Abstract
A debrominative oxygenation protocol has been developed for the conversion of α-bromo-α,α-dialkyl-substituted carbonyl compounds to their corresponding α-hydroxy analogues. For example, stirring a solution of α-bromoisobutyrophenone and 2-aryl-1,3-dimethylbenzimidazoline (BIH-Ar) at room temperature under an air atmosphere leads to the efficient formation of α-hydroperoxyisobutyrophenone, which can be converted to α-hydroxyisobutyrophenone using Me2S reduction. In contrast, reaction of α-bromoacetophenone under the same conditions produces the α-hydrogenated product acetophenone. α-Keto-alkyl and benzimidazolyl radicals (BI•-Ar), generated via dissociative electron transfer from BIH-Ar to α-bromoketone substrates, serve as key intermediates in the oxidation and reduction processes. The dramatic switch from hydrogenation to oxygenation is attributed to a steric effect of α-alkyl substituents, which causes hydrogen atom abstraction from sterically crowded BIH-Ar to α-keto-alkyl radicals to be slow and enable preferential reaction with molecular oxygen. Generation of the α-keto-alkyl radical and BI•-Ar intermediates in these process and their sterically governed hydrogen atom transfer reactions are supported by results arising from DFT calculations. Moreover, an electron spin resonance study showed that visible light irradiation of phenyl benzimidazoline (BIH-Ph) in the presence of molecular oxygen produces the benzimidazolyl radical (BI•-Ph). The addition of thiophenol into the reaction of α-bromoisobutyrophenone and BIH-Ph predominantly produced α-phenylthiolated isobutyrophenone even if a high concentration of molecular oxygen exists. Furthermore, the developed protocol was applied to other α-bromo-α,α-dialkylated carbonyl compounds.
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Affiliation(s)
- Eietsu Hasegawa
- Department
of Chemistry, Faculty of Science, Niigata
University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
- E-mail:
| | - Naoki Yoshioka
- Department
of Chemistry, Faculty of Science, Niigata
University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Tsukasa Tanaka
- Department
of Chemistry, Faculty of Science, Niigata
University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Taisei Nakaminato
- Department
of Chemistry, Faculty of Science, Niigata
University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Kazuki Oomori
- Department
of Chemistry, Faculty of Science, Niigata
University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Tadaaki Ikoma
- Department
of Chemistry, Faculty of Science, Niigata
University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Hajime Iwamoto
- Department
of Chemistry, Faculty of Science, Niigata
University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Kan Wakamatsu
- Department
of Chemistry, Faculty of Science, Okayama
University of Science, 1-1 Ridaicho, Kita-ku, Okayama 700-0005, Japan
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19
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Hasegawa E, Tanaka T, Izumiya N, Kiuchi T, Ooe Y, Iwamoto H, Takizawa SY, Murata S. Protocol for Visible-Light-Promoted Desulfonylation Reactions Utilizing Catalytic Benzimidazolium Aryloxide Betaines and Stoichiometric Hydride Donor Reagents. J Org Chem 2020; 85:4344-4353. [PMID: 32073264 DOI: 10.1021/acs.joc.0c00038] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
An unprecedented photocatalytic system consisting of benzimidazolium aryloxide betaines (BI+-ArO-) and stoichiometric hydride reducing reagents was developed for carrying out desulfonylation reactions of N-sulfonyl-indoles, -amides, and -amines, and α-sulfonyl ketones. Measurements of absorption spectra and cyclic voltammograms as well as density functional theory (DFT) calculations were carried out to gain mechanistic information. In the catalytic system, visible-light-activated benzimidazoline aryloxides (BIH-ArO-), generated in situ by hydride reduction of the corresponding betaines BI+-ArO-, donate both an electron and a hydrogen atom to the substrates. A modified protocol was also developed so that a catalytic quantity of more easily prepared hydroxyaryl benzimidazolines (BIH-ArOH) is used along with a stoichiometric hydride donor to promote the photochemical desulfonylation reactions.
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Affiliation(s)
- Eietsu Hasegawa
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Tsukasa Tanaka
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Norihiro Izumiya
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Takehiro Kiuchi
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Yuuki Ooe
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Hajime Iwamoto
- Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan
| | - Shin-Ya Takizawa
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Shigeru Murata
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
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20
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Bouchet LM, Heredia AA, Argüello JE, Schmidt LC. Riboflavin as Photoredox Catalyst in the Cyclization of Thiobenzanilides: Synthesis of 2-Substituted Benzothiazoles. Org Lett 2019; 22:610-614. [DOI: 10.1021/acs.orglett.9b04384] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Lydia M. Bouchet
- INFIQC−CONICET-UNC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Adrián A. Heredia
- INFIQC−CONICET-UNC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Juan E. Argüello
- INFIQC−CONICET-UNC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Luciana C. Schmidt
- INFIQC−CONICET-UNC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
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21
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García-Sánchez A, Gomez-Mendoza M, Barawi M, Villar-Garcia IJ, Liras M, Gándara F, de la Peña O’Shea VA. Fundamental Insights into Photoelectrocatalytic Hydrogen Production with a Hole-Transport Bismuth Metal–Organic Framework. J Am Chem Soc 2019; 142:318-326. [DOI: 10.1021/jacs.9b10261] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Alba García-Sánchez
- Photoactivated Processes Unit, IMDEA Energy Institute, Technological Park of Móstoles, Avda. Ramón de la Sagra 3, 28935 Madrid, Spain
| | - Miguel Gomez-Mendoza
- Photoactivated Processes Unit, IMDEA Energy Institute, Technological Park of Móstoles, Avda. Ramón de la Sagra 3, 28935 Madrid, Spain
| | - Mariam Barawi
- Photoactivated Processes Unit, IMDEA Energy Institute, Technological Park of Móstoles, Avda. Ramón de la Sagra 3, 28935 Madrid, Spain
| | - Ignacio J. Villar-Garcia
- Photoactivated Processes Unit, IMDEA Energy Institute, Technological Park of Móstoles, Avda. Ramón de la Sagra 3, 28935 Madrid, Spain
| | - Marta Liras
- Photoactivated Processes Unit, IMDEA Energy Institute, Technological Park of Móstoles, Avda. Ramón de la Sagra 3, 28935 Madrid, Spain
| | - Felipe Gándara
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - Víctor A. de la Peña O’Shea
- Photoactivated Processes Unit, IMDEA Energy Institute, Technological Park of Móstoles, Avda. Ramón de la Sagra 3, 28935 Madrid, Spain
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22
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Yang Y, Lu Z, Xu X. Phenacyl Xanthates: A Photoremovable Protecting Group for Alcohols under Visible Light. ASIAN J ORG CHEM 2019. [DOI: 10.1002/ajoc.201900576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Yong‐Qing Yang
- School of PharmacyJiangsu University No. 301 Xuefu Road Zhenjiang, Jiangsu Province 212013 China
| | - Zheng Lu
- School of PharmacyJiangsu University No. 301 Xuefu Road Zhenjiang, Jiangsu Province 212013 China
| | - Ximing Xu
- School of PharmacyJiangsu University No. 301 Xuefu Road Zhenjiang, Jiangsu Province 212013 China
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23
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Ramirez NP, Lana-Villarreal T, Gonzalez-Gomez JC. Direct Decarboxylative Allylation and Arylation of Aliphatic Carboxylic Acids Using Flavin-Mediated Photoredox Catalysis. European J Org Chem 2019. [DOI: 10.1002/ejoc.201900888] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Nieves P. Ramirez
- Instituto de Síntesis Orgánica y Departamento de Química Orgánica; Universidad de Alicante; Apdo 99, E -03080 Alicante Spain
| | - Teresa Lana-Villarreal
- Instituto de Electroquímica y Departamento de Química Física; Universidad de Alicante; Spain
| | - Jose C. Gonzalez-Gomez
- Instituto de Síntesis Orgánica y Departamento de Química Orgánica; Universidad de Alicante; Apdo 99, E -03080 Alicante Spain
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24
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González-Muñoz D, Casado-Sánchez A, del Hierro I, Gómez-Ruiz S, Cabrera S, Alemán J. Size-selective mesoporous silica-based Pt(II) complex as efficient and reusable photocatalytic material. J Catal 2019. [DOI: 10.1016/j.jcat.2019.04.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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25
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Casado-Sánchez A, Uygur M, González-Muñoz D, Aguilar-Galindo F, Nova-Fernández JL, Arranz-Plaza J, Díaz-Tendero S, Cabrera S, Mancheño OG, Alemán J. 8-Mercaptoquinoline as a Ligand for Enhancing the Photocatalytic Activity of Pt(II) Coordination Complexes: Reactions and Mechanistic Insights. J Org Chem 2019; 84:6437-6447. [PMID: 30998010 DOI: 10.1021/acs.joc.9b00520] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A family of quinoline-platinum(II) complexes as efficient photocatalysts is presented. Their key characteristic is their easy preparation by coordination of the readily available 8-hydroxy- or 8-thio-quinoline ligands, which are well known for their strong chelating ability to different metal ions. In the different photochemical transformations investigated, such as cross-dehydrogenative coupling, oxidation of arylboronic acids, and asymmetric alkylation of aldehydes, 8-mercaptoquinoline-Pt(II) complex proved to be the most general catalyst. Moreover, quenching experiments showed that, contrary to related methods reported in the literature, these complexes followed an oxidative quenching mechanism in all transformations studied. Besides, simulations performed with high-level ab initio methods of the complexes have helped to understand their photocatalytic activity.
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Affiliation(s)
| | - Mustafa Uygur
- Organic Chemistry Department , University of Münster , 48149 Münster , Germany
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26
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Ramirez NP, König B, Gonzalez-Gomez JC. Decarboxylative Cyanation of Aliphatic Carboxylic Acids via Visible-Light Flavin Photocatalysis. Org Lett 2019; 21:1368-1373. [DOI: 10.1021/acs.orglett.9b00064] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Nieves P. Ramirez
- Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain
| | - Burkhard König
- Faculty of Chemistry and Pharmacy, University of Regensburg, D-93040 Regensburg, Germany
| | - Jose C. Gonzalez-Gomez
- Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain
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27
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März M, Kohout M, Neveselý T, Chudoba J, Prukała D, Niziński S, Sikorski M, Burdziński G, Cibulka R. Azodicarboxylate-free esterification with triphenylphosphine mediated by flavin and visible light: method development and stereoselectivity control. Org Biomol Chem 2018; 16:6809-6817. [PMID: 30203820 DOI: 10.1039/c8ob01822g] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Triphenylphosphine (Ph3P) activated by various electrophiles (e.g., alkyl diazocarboxylates) represents an effective mediator of esterification and other nucleophilic substitution reactions. We report herein an aza-reagent-free procedure using flavin catalyst (3-methyl riboflavin tetraacetate), triphenylphosphine, and visible light (448 nm), which allows effective esterification of aromatic and aliphatic carboxylic acids with alcohols. Mechanistic study confirmed that photoinduced electron transfer from triphenylphosphine to excited flavin with the formation of Ph3P˙+ is a crucial step in the catalytic cycle. This allows reactive alkoxyphosphonium species to be generated by reaction of an alcohol with Ph3P˙+ followed by single-electron oxidation. Unexpected stereoselectivity control by the solvent was observed, allowing switching from inversion to retention of configuration during esterification of (S)- or (R)-1-phenylethanol; for example with phenylacetic acid, the ratio shifting from 10 : 90 (retention : inversion) in trifluoromethylbenzene to 99.9 : 0.1 in acetonitrile. Our method uses nitrobenzene to regenerate the flavin photocatalyst. This new approach to flavin re-oxidation has also been successfully proved in benzyl alcohol oxidation, which is a "standard" process among flavin-mediated photooxidations.
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Affiliation(s)
- Michal März
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic.
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28
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Ma M, Hao W, Ma L, Zheng Y, Lian P, Wan X. Interception of Radicals by Molecular Oxygen and Diazo Compounds: Direct Synthesis of Oxalate Esters Using Visible-Light Catalysis. Org Lett 2018; 20:5799-5802. [DOI: 10.1021/acs.orglett.8b02487] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Meihua Ma
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Weiwei Hao
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Liang Ma
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Yonggao Zheng
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Pengcheng Lian
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Xiaobing Wan
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
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29
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Naumann R, Lehmann F, Goez M. Micellized Tris(bipyridine)ruthenium Catalysts Affording Preparative Amounts of Hydrated Electrons with a Green Light-Emitting Diode. Chemistry 2018; 24:13259-13269. [DOI: 10.1002/chem.201801955] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/15/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Robert Naumann
- Martin-Luther-Universität Halle-Wittenberg; Institut für Chemie; Kurt-Mothes-Str. 2 06120 Halle (Saale) Germany
| | - Florian Lehmann
- Martin-Luther-Universität Halle-Wittenberg; Institut für Chemie; Kurt-Mothes-Str. 2 06120 Halle (Saale) Germany
| | - Martin Goez
- Martin-Luther-Universität Halle-Wittenberg; Institut für Chemie; Kurt-Mothes-Str. 2 06120 Halle (Saale) Germany
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30
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Naumann R, Goez M. A Green-LED Driven Source of Hydrated Electrons Characterized from Microseconds to Hours and Applied to Cross-Couplings. Chemistry 2018. [PMID: 29528157 DOI: 10.1002/chem.201800626] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Robert Naumann
- Martin-Luther-Universität Halle-Wittenberg; Institut für Chemie; Kurt-Mothes-Str. 2 06120 Halle (Saale) Germany
| | - Martin Goez
- Martin-Luther-Universität Halle-Wittenberg; Institut für Chemie; Kurt-Mothes-Str. 2 06120 Halle (Saale) Germany
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31
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Naumann R, Kerzig C, Goez M. Laboratory-scale photoredox catalysis using hydrated electrons sustainably generated with a single green laser. Chem Sci 2017; 8:7510-7520. [PMID: 29163905 PMCID: PMC5676201 DOI: 10.1039/c7sc03514d] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/12/2017] [Indexed: 12/20/2022] Open
Abstract
The ruthenium-tris-bipyridyl dication as catalyst combined with the ascorbate dianion as bioavailable sacrificial donor provides the first regenerative source of hydrated electrons for chemical syntheses on millimolar scales. This electron generator is operated simply by illumination with a frequency-doubled Nd:YAG laser (532 nm) running at its normal repetition rate. Much more detailed information than by product studies alone was obtained by photokinetical characterization from submicroseconds (time-resolved laser flash photolysis) up to one hour (preparative photolysis). The experiments on short timescales established a reaction mechanism more complex than previously thought, and proved the catalytic action by unchanged concentration traces of the key transients over a number of flashes so large that the accumulated electron total surpassed the catalyst concentration many times. Preparative photolyses revealed that the sacrificial donor greatly enhances the catalyst stability through quenching the initial metal-to-ligand charge-transfer state before destructive dd states can be populated from it, such that the efficiency of this electron generator is no longer limited by catalyst decomposition but by electron scavenging by the accumulating oxidation products of the ascorbate. Applications covered dechlorinations of selected aliphatic and aromatic chlorides and the reduction of a model ketone. All these substrates are impervious to photoredox catalysts exhibiting lower reducing power than the hydrated electron, but the combination of an extremely negative standard potential and a long unquenched life allowed turnover numbers up to 1400 with our method.
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Affiliation(s)
- Robert Naumann
- Martin-Luther-Universität Halle-Wittenberg , Institut für Chemie , Kurt-Mothes-Str. 2 , D-06120 Halle (Saale) , Germany .
| | - Christoph Kerzig
- Martin-Luther-Universität Halle-Wittenberg , Institut für Chemie , Kurt-Mothes-Str. 2 , D-06120 Halle (Saale) , Germany .
| | - Martin Goez
- Martin-Luther-Universität Halle-Wittenberg , Institut für Chemie , Kurt-Mothes-Str. 2 , D-06120 Halle (Saale) , Germany .
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32
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Marin M, Miranda MA, Marin ML. A comprehensive mechanistic study on the visible-light photocatalytic reductive dehalogenation of haloaromatics mediated by Ru(bpy)3Cl2. Catal Sci Technol 2017. [DOI: 10.1039/c7cy01231d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fast kinetic data from time-resolved emission spectroscopy shine light on the mechanism involved in the Ru(bpy)32+-photocatalytic reduction of halonitrobenzenes.
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Affiliation(s)
- Mireia Marin
- Instituto de Tecnología Química
- Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas
- Spain
| | - Miguel A. Miranda
- Instituto de Tecnología Química
- Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas
- Spain
| | - M. Luisa Marin
- Instituto de Tecnología Química
- Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas
- Spain
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