1
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Rehpenn A, Hindelang S, Truong KN, Pöthig A, Storch G. Enhancing Flavins Photochemical Activity in Hydrogen Atom Abstraction and Triplet Sensitization through Ring-Contraction. Angew Chem Int Ed Engl 2024; 63:e202318590. [PMID: 38339882 DOI: 10.1002/anie.202318590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024]
Abstract
The isoalloxazine heterocycle of flavin cofactors reacts with various nucleophiles to form covalent adducts with important functions in enzymes. Molecular flavin models allow for the characterization of such adducts and the study of their properties. A fascinating set of reactions occurs when flavins react with hydroxide base, which leads to imidazolonequinoxalines, ring-contracted flavins, with so far unexplored activity. We report a systematic study of the photophysical properties of this new chromophore by absorption and emission spectroscopy as well as cyclic voltammetry. Excited, ring-contracted flavins are significantly stronger hydrogen atom abstractors when compared to the parent flavins, which allowed the direct trifluoromethylthiolation of aliphatic methine positions (bond dissociation energy (BDE) of 400.8 kJ mol-1). In an orthogonal activity, their increased triplet energy (E(S0←T1)=244 kJ mol-1) made sensitized reactions possible which exceeded the power of standard flavins. Combining both properties, ring-contracted flavin catalysts enabled the one-pot, five-step transformation of α-tropolone into trans-3,4-disubstituted cyclopentanones. We envision this new class of flavin-derived chromophores to open up new modes of reactivity that are currently impossible with unmodified flavins.
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Affiliation(s)
- Andreas Rehpenn
- Technical University of Munich (TUM), School of Natural Sciences and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
| | - Stephan Hindelang
- Technical University of Munich (TUM), School of Natural Sciences and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
| | - Khai-Nghi Truong
- Rigaku Europe SE, Hugenottenallee 167, 63263, Neu-Isenburg, Germany
| | - Alexander Pöthig
- Technical University of Munich (TUM), School of Natural Sciences and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
| | - Golo Storch
- Technical University of Munich (TUM), School of Natural Sciences and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
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2
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Guo H, Qiu Y, Liu S, Zhang X, Zhao J. Tailoring flavin-based photosensitizers for efficient photooxidative coupling of benzylic amines. Phys Chem Chem Phys 2023; 26:161-173. [PMID: 38086643 DOI: 10.1039/d3cp04579j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Photooxidative coupling of benzylic amines using naturally abundant O2 as an oxidant under visible light irradiation is an alternative green approach to synthesis imines and is of both fundamental and practical significance. We investigated the photophysical properties of flavin (FL) that is a naturally available sensitizer and its derivatives, i.e. 9-bromoflavin (MB-FL), 7,8-dibromoflavin (DB-FL) and 10-phenylflavin (Ph-FL), as well as the performance of these FL-based sensitizers (FLPSs) in the photooxidative coupling of benzylic amines to imines combining experimental and theoretical efforts. We showed that chemical functionalization with Br and phenyl effectively improves the photophysical properties of these FLPSs, in terms of absorption in the visible light range, singlet oxygen quantum yields, triplet lifetime, etc. Apart from nearly quantitative selectivity for the production of imines, the performance of DB-FL is superior to those of other FLPSs, and it is among the best photocatalysts for imine synthesis. Specifically, 0.5 mol% DB-FL is capable of converting 91% of 0.2 mmol benzylamine and more than 80% of 0.2 mmol fluorobenzylic amine derivatives into their corresponding imines in 5 h batch runs. Mechanistic investigation finely explained the observed photophysical properties of FLPSs and highlighted the dominant role of electron transfer in FLPS sensitized coupling of benzylic amines to imines. This work not only helps to understand the pathways for photocatalysis with FLPSs but also paves the way for the design of novel and efficient PSs to promote organic synthesis.
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Affiliation(s)
- Huimin Guo
- School of Chemistry, Dalian University of Technology, No. 2, Linggong Road, Dalian, 116024, P. R. China.
| | - Yang Qiu
- School of Chemistry, Dalian University of Technology, No. 2, Linggong Road, Dalian, 116024, P. R. China.
| | - Siyu Liu
- School of Chemistry, Dalian University of Technology, No. 2, Linggong Road, Dalian, 116024, P. R. China.
| | - Xiangyu Zhang
- School of Chemistry, Dalian University of Technology, No. 2, Linggong Road, Dalian, 116024, P. R. China.
| | - Jianzhang Zhao
- School of Chemistry, Dalian University of Technology, No. 2, Linggong Road, Dalian, 116024, P. R. China.
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3
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Han J, Haines CA, Piane JJ, Filien LL, Nacsa ED. An Electrochemical Design for Catalytic Dehydration: Direct, Room-Temperature Esterification without Acid or Base Additives. J Am Chem Soc 2023. [PMID: 37436909 DOI: 10.1021/jacs.3c04732] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
An electrochemical approach has been leveraged to underpin a new conceptual platform for dehydration reactions, which has been demonstrated in the context of esterification. Esters were prepared from the corresponding acid and alcohol partners at room temperature without acid or base additives and without consuming stoichiometric reagents. This methodology therefore addresses key complications that plague esterification and dehydration reactions more broadly and that represent a leading challenge in synthetic chemistry.
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Affiliation(s)
- Jian Han
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Christopher A Haines
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Jacob J Piane
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Leila L Filien
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Eric D Nacsa
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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4
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Bera N, Lenka BS, König B, Sarkar D. Riboflavin Photocatalyzed Dearomative Spiro-Etherification of Naphthols. J Org Chem 2023. [PMID: 37356110 DOI: 10.1021/acs.joc.2c03037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
The dearomative spiro-etherification of naphthols is achieved using catalytic amounts of riboflavin tetracetate (RFTA) as a photosensitizer and molecular oxygen as a terminal oxidizing agent under blue light (440 nm) irradiation in the presence of acid. The presence of acid increases the photooxidation power of RFTA and facilitates the dearomatization reaction.
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Affiliation(s)
- Nabakumar Bera
- Department of Chemistry, National Institute of Technology, Rourkela, Rourkela 769008, India
| | - Bhabani Sankar Lenka
- Department of Chemistry, Indian Institute of Technology, Indore, Madhya Pradesh 453552, India
| | - Burkhard König
- Department of Chemistry and Pharmazie, University of Regensburg, 93040 Regensburg, Germany
| | - Debayan Sarkar
- Department of Chemistry, Indian Institute of Technology, Indore, Madhya Pradesh 453552, India
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5
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Rehpenn A, Walter A, Storch G. Molecular flavin catalysts for C-H functionalisation and derivatisation of dehydroamino acids. Chem Sci 2022; 13:14151-14156. [PMID: 36540823 PMCID: PMC9728571 DOI: 10.1039/d2sc04341f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/04/2022] [Indexed: 03/12/2024] Open
Abstract
In nature, the isoalloxazine heterocycle of flavin cofactors undergoes reversible covalent bond formation with a variety of different reaction partners. These intermediates play a crucial role inter alia as the signalling states and in selective catalysis reactions. In the organic laboratory, covalent adducts with a new carbon-carbon bond have been observed with photochemically excited flavins but have, so far, only been regarded as dead-end side products. We have identified a series of molecular flavins that form adducts resulting in a new C-C bond at the C4a-position through allylic C-H activation and dehydroamino acid oxidation. Typically, these reactions are of radical nature and a stepwise pathway is assumed. We could demonstrate that these adducts are no dead-end and that the labile C-C bond can be cleaved by adding the persistent radical TEMPO leading to flavin regeneration and alkoxyamine-functionalised substrates. Our method allows for the catalytic oxidation of dehydroamino acids (16 examples) and we show that the acylimine products serve as versatile starting points for diversification. The present results are envisioned to stimulate the design of further catalytic reactions involving intermediates at the flavin C4a-position and their reactivity towards metal complexes or other persistent organic radicals. Our method for dehydrobutyrine derivatisation is orthogonal to the currently used methods (i.e., nucleophilic attack or radical addition) and offers new perspectives for peptide natural product diversification.
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Affiliation(s)
- Andreas Rehpenn
- School of Natural Sciences and Catalysis Research Center (CRC), Technical University of Munich (TUM) Lichtenbergstr. 4 85747 Garching Germany
| | - Alexandra Walter
- School of Natural Sciences and Catalysis Research Center (CRC), Technical University of Munich (TUM) Lichtenbergstr. 4 85747 Garching Germany
| | - Golo Storch
- School of Natural Sciences and Catalysis Research Center (CRC), Technical University of Munich (TUM) Lichtenbergstr. 4 85747 Garching Germany
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6
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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] [Key Words] [MESH Headings] [Grants] [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 ChemistryUniversity of Chemistry and Technology, PragueTechnická 5166 28Prague 6Czech Republic
| | - David Král Lesný
- Department of Organic ChemistryUniversity of Chemistry and Technology, PragueTechnická 5166 28Prague 6Czech Republic
| | - Eva Svobodová
- Department of Organic ChemistryUniversity of Chemistry and Technology, PragueTechnická 5166 28Prague 6Czech Republic
| | - Irena Hoskovcová
- Department of Inorganic ChemistryUniversity of Chemistry and Technology, PragueTechnická 5166 28Prague 6Czech Republic
| | - Nataliya Archipowa
- Institute for Biophysics and Physical BiochemistryUniversity of RegensburgD-93053RegensburgGermany
| | - Roger Jan Kutta
- Institute of Physical and Theoretical ChemistryUniversity of RegensburgD-93053RegensburgGermany
| | - Radek Cibulka
- Department of Organic ChemistryUniversity of Chemistry and Technology, PragueTechnická 5166 28Prague 6Czech Republic
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7
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Hao W, Che S, Li J, Luo J, Zhang W, Chen Y, Zhao Z, Wei H, Xie W. Synthesis of Berberine and Canagliflozin Chimera and Investigation into New Antibacterial Activity and Mechanisms. Molecules 2022; 27:molecules27092948. [PMID: 35566298 PMCID: PMC9100802 DOI: 10.3390/molecules27092948] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/01/2022] [Accepted: 05/03/2022] [Indexed: 11/25/2022] Open
Abstract
Berberine is an isoquinoline alkaloid isolated from Chinese herbal medicines such as Coptis chinensis. It has many pharmacological actions, such as antibacterial, hypoglycemic, anti-inflammatory, and so on. However, due to the low lipophilicity of berberine, it is difficult to penetrate the bacterial cell membrane and also difficult to be absorbed orally and usually needs a relatively high dose to achieve the ideal effect. The purpose of this study is to transform the structure of berberine in order to improve the bioavailability of berberine and reduce the dosage. Moreover, we introduce a pharmacophore named Canagliflozin, a hypoglycemic drug (which was also found to have potential anti-bacterial activity) into BBR to see whether this new compound has more existed activities. We at first connected berberine with Canagliflozin, to form a new compound (BC) and see whether BC has synergic effects. We use microbroth dilution method to determine the minimum inhibitory concentration of BC, determine the bacterial growth with the enzyme labeling instrument, observe the formation of bacterial biofilm with crystal violet staining method, observe the bacterial morphology with field emission scanning electron microscope, and determine the intracellular protein with SDS-PAGE. The above indicators reflect the damage of BC to bacteria. New compound BC was successfully obtained by chemical synthesis. The minimal inhibitory concentration of compound BC on three bacteria was significantly better than that of berberine and canagliflozin alone and the combination of berberine and canagliflozin. Moreover, compound BC has obvious destructive effect on bacterial morphology and biofilm, and the compound also has destructive effect on intracellular proteins. Therefore, new compound BC has broad-spectrum antibacterial activity and the inhibitory effect of BC might play a role by destroying the integrity of biofilm and the intracellular protein of bacteria. In conclusion, we create a new molecular entity of berberine and Canagliflozin chimera and open up a new prospect for berberine derivatives in the treatment of bacterial infection.
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Affiliation(s)
- Wenhui Hao
- State Key Laboratory of Chemical Oncogenomics, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; (W.H.); (J.L.); (W.Z.); (Y.C.)
| | - Shiying Che
- School of Chemistry and Materials Science, Huaihua University, Huaihua 418000, China; (S.C.); (J.L.)
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xi’an-Xianyang New Ecomic Zone, Xianyang 712046, China
- Key Laboratory of Research and Utilization of Ethnomedicinal Plant Resources of Hunan Province, Huaihua University, Huaihua 418000, China
| | - Jinsheng Li
- School of Chemistry and Materials Science, Huaihua University, Huaihua 418000, China; (S.C.); (J.L.)
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xi’an-Xianyang New Ecomic Zone, Xianyang 712046, China
- Key Laboratory of Research and Utilization of Ethnomedicinal Plant Resources of Hunan Province, Huaihua University, Huaihua 418000, China
| | - Jingyi Luo
- State Key Laboratory of Chemical Oncogenomics, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; (W.H.); (J.L.); (W.Z.); (Y.C.)
- Shenzhen Key Laboratory of Health Science and Technology, Institute of Biopharmaceutical and Health Engineering, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Wanqiu Zhang
- State Key Laboratory of Chemical Oncogenomics, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; (W.H.); (J.L.); (W.Z.); (Y.C.)
- Shenzhen Key Laboratory of Health Science and Technology, Institute of Biopharmaceutical and Health Engineering, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Yang Chen
- State Key Laboratory of Chemical Oncogenomics, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; (W.H.); (J.L.); (W.Z.); (Y.C.)
- Shenzhen Key Laboratory of Health Science and Technology, Institute of Biopharmaceutical and Health Engineering, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
| | - Zijian Zhao
- School of Chemistry and Materials Science, Huaihua University, Huaihua 418000, China; (S.C.); (J.L.)
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xi’an-Xianyang New Ecomic Zone, Xianyang 712046, China
- Key Laboratory of Research and Utilization of Ethnomedicinal Plant Resources of Hunan Province, Huaihua University, Huaihua 418000, China
- Correspondence: (Z.Z.); (H.W.); (W.X.)
| | - Hao Wei
- College of Pharmacy, Shaanxi University of Chinese Medicine, Xi’an-Xianyang New Ecomic Zone, Xianyang 712046, China
- Correspondence: (Z.Z.); (H.W.); (W.X.)
| | - Weidong Xie
- State Key Laboratory of Chemical Oncogenomics, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China; (W.H.); (J.L.); (W.Z.); (Y.C.)
- Shenzhen Key Laboratory of Health Science and Technology, Institute of Biopharmaceutical and Health Engineering, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
- Correspondence: (Z.Z.); (H.W.); (W.X.)
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8
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Trenker S, Grunenberg L, Banerjee T, Savasci G, Poller LM, Muggli KIM, Haase F, Ochsenfeld C, Lotsch BV. A flavin-inspired covalent organic framework for photocatalytic alcohol oxidation. Chem Sci 2021; 12:15143-15150. [PMID: 34909156 PMCID: PMC8612393 DOI: 10.1039/d1sc04143f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 11/02/2021] [Indexed: 12/02/2022] Open
Abstract
Covalent organic frameworks (COFs) offer a number of key properties that predestine them to be used as heterogeneous photocatalysts, including intrinsic porosity, long-range order, and light absorption. Since COFs can be constructed from a practically unlimited library of organic building blocks, these properties can be precisely tuned by choosing suitable linkers. Herein, we report the construction and use of a novel COF (FEAx-COF) photocatalyst, inspired by natural flavin cofactors. We show that the functionality of the alloxazine chromophore incorporated into the COF backbone is retained and study the effects of this heterogenization approach by comparison with similar molecular photocatalysts. We find that the integration of alloxazine chromophores into the framework significantly extends the absorption spectrum into the visible range, allowing for photocatalytic oxidation of benzylic alcohols to aldehydes even with low-energy visible light. In addition, the activity of the heterogeneous COF photocatalyst is less dependent on the chosen solvent, making it more versatile compared to molecular alloxazines. Finally, the use of oxygen as the terminal oxidant renders FEAx-COF a promising and “green” heterogeneous photocatalyst. In this manuscript, we report the development of a novel alloxazine COF inspired by naturally occurring flavin cofactors for photoredox catalysis.![]()
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Affiliation(s)
- Stefan Trenker
- Max Planck Institute for Solid State Research Heisenbergstr. 1 70569 Stuttgart Germany .,Department of Chemistry, University of Munich (LMU) Butenandtstr. 5-13 81377 Munich Germany.,Center for Nanoscience Schellingstr. 4 80799 Munich Germany
| | - Lars Grunenberg
- Max Planck Institute for Solid State Research Heisenbergstr. 1 70569 Stuttgart Germany .,Department of Chemistry, University of Munich (LMU) Butenandtstr. 5-13 81377 Munich Germany
| | - Tanmay Banerjee
- Department of Chemistry, Birla Institute of Technology and Science Pilani, Pilani Campus Rajasthan 333031 India
| | - Gökcen Savasci
- Max Planck Institute for Solid State Research Heisenbergstr. 1 70569 Stuttgart Germany .,Department of Chemistry, University of Munich (LMU) Butenandtstr. 5-13 81377 Munich Germany.,Center for Nanoscience Schellingstr. 4 80799 Munich Germany.,Karlsruhe Institute of Technology (KIT), IFG - Institute for Functional Interfaces Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen Germany
| | - Laura M Poller
- Department of Chemistry, University of Munich (LMU) Butenandtstr. 5-13 81377 Munich Germany
| | - Katharina I M Muggli
- Department of Chemistry, University of Munich (LMU) Butenandtstr. 5-13 81377 Munich Germany
| | - Frederik Haase
- Karlsruhe Institute of Technology (KIT), IFG - Institute for Functional Interfaces Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen Germany
| | - Christian Ochsenfeld
- Max Planck Institute for Solid State Research Heisenbergstr. 1 70569 Stuttgart Germany .,Department of Chemistry, University of Munich (LMU) Butenandtstr. 5-13 81377 Munich Germany.,Center for Nanoscience Schellingstr. 4 80799 Munich Germany.,e-conversion Cluster of Excellence Lichtenbergstr. 4a, 85748 Garching Germany
| | - Bettina V Lotsch
- Max Planck Institute for Solid State Research Heisenbergstr. 1 70569 Stuttgart Germany .,Department of Chemistry, University of Munich (LMU) Butenandtstr. 5-13 81377 Munich Germany.,Center for Nanoscience Schellingstr. 4 80799 Munich Germany.,e-conversion Cluster of Excellence Lichtenbergstr. 4a, 85748 Garching Germany
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9
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Manna K, Ganguly T, Baitalik S, Jana R. Visible-Light- and PPh 3-Mediated Direct C-N Coupling of Nitroarenes and Boronic Acids at Ambient Temperature. Org Lett 2021; 23:8634-8639. [PMID: 34643396 DOI: 10.1021/acs.orglett.1c03343] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We present here a metal-free, visible-light- and triphenylphosphine-mediated intermolecular, reductive amination between nitroarenes and boronic acids at ambient temperature without any photocatalyst. Mechanistically, a slow reduction of nitroarenes to a nitroso and, finally, a nitrene intermediate occurs that leads to the amination product with concomitant 1,2-aryl/-alkyl migration from a boronate complex. A wide range of nitroarenes underwent C-N coupling with aryl-/alkylboronic acids providing high yields.
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Affiliation(s)
- Kartic Manna
- Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, West Bengal, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, Uttar Pradesh, India
| | - Tanusree Ganguly
- Inorganic Chemistry Section, Department of Chemistry, Jadavpur University, Kolkata 700032, West Bengal, India
| | - Sujoy Baitalik
- Inorganic Chemistry Section, Department of Chemistry, Jadavpur University, Kolkata 700032, West Bengal, India
| | - Ranjan Jana
- Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, West Bengal, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, Uttar Pradesh, India
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10
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Hassan Tolba A, Krupička M, Chudoba J, Cibulka R. Amide Bond Formation via Aerobic Photooxidative Coupling of Aldehydes with Amines Catalyzed by a Riboflavin Derivative. Org Lett 2021; 23:6825-6830. [PMID: 34424722 DOI: 10.1021/acs.orglett.1c02391] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We report an effective, operationally simple, and environmentally friendly system for the synthesis of tertiary amides by the oxidative coupling of aromatic or aliphatic aldehydes with amines mediated by riboflavin tetraacetate (RFTA), an inexpensive organic photocatalyst, and visible light using oxygen as the sole oxidant. The method is based on the oxidative power of an excited flavin catalyst and the relatively low oxidation potential of the hemiaminal formed by amine to aldehyde addition.
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11
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Meng H, Sun K, Xu Z, Tian L, Wang Y. P(III)‐Assisted Electrochemical Access to Ureas via in situ Generation of Isocyanates from Hydroxamic Acids. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Haiwen Meng
- Technical Institute of Fluorochemistry (TIF) Institute of Advanced Synthesis School of Chemistry and Molecular Engineering Nanjing Tech University 211816 Nanjing China
| | - Kunhui Sun
- Technical Institute of Fluorochemistry (TIF) Institute of Advanced Synthesis School of Chemistry and Molecular Engineering Nanjing Tech University 211816 Nanjing China
| | - Zhimin Xu
- Technical Institute of Fluorochemistry (TIF) Institute of Advanced Synthesis School of Chemistry and Molecular Engineering Nanjing Tech University 211816 Nanjing China
| | - Lifang Tian
- Technical Institute of Fluorochemistry (TIF) Institute of Advanced Synthesis School of Chemistry and Molecular Engineering Nanjing Tech University 211816 Nanjing China
| | - Yahui Wang
- Technical Institute of Fluorochemistry (TIF) Institute of Advanced Synthesis School of Chemistry and Molecular Engineering Nanjing Tech University 211816 Nanjing China
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12
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Teets TS, Wu Y, Kim D. Photophysical Properties and Redox Potentials of Photosensitizers for Organic Photoredox Transformations. Synlett 2021. [DOI: 10.1055/a-1390-9065] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractPhotoredox catalysis has proven to be a powerful tool in synthetic organic chemistry. The rational design of photosensitizers with improved photocatalytic performance constitutes a major advancement in photoredox organic transformations. This review summarizes the fundamental ground-state and excited-state photophysical and electrochemical attributes of molecular photosensitizers, which are important determinants of their photocatalytic reactivity.
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13
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Hartman T, Reisnerová M, Chudoba J, Svobodová E, Archipowa N, Kutta RJ, Cibulka R. Photocatalytic Oxidative [2+2] Cycloelimination Reactions with Flavinium Salts: Mechanistic Study and Influence of the Catalyst Structure. Chempluschem 2021; 86:373-386. [DOI: 10.1002/cplu.202000767] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/22/2020] [Indexed: 01/19/2023]
Affiliation(s)
- Tomáš Hartman
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Martina Reisnerová
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Josef Chudoba
- Central Laboratories 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
| | - Nataliya Archipowa
- Manchester Institute of Biotechnology and School of Chemistry The University of Manchester Manchester M1 7DN United Kingdom
| | - Roger Jan Kutta
- Institute of Physical and Theoretical Chemistry University of Regensburg 93040 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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14
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Shao X, Zheng Y, Ramadoss V, Tian L, Wang Y. Recent advances in P III-assisted deoxygenative reactions under photochemical or electrochemical conditions. Org Biomol Chem 2020; 18:5994-6005. [PMID: 32692327 DOI: 10.1039/d0ob01083a] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The nucleophilic substitution reactions of hydroxyl groups are one of the most fundamental and widely spread transformations in organic chemistry. Among them, PIII-mediated deoxygenative nucleophilic substitution reactions, such as the Mitsunobu reaction, are frequently used strategies and often require stoichiometric oxidants to activate PIII reagents to induce the desired reactions. It has been illustrated that PIII reagents can be oxidized into the corresponding radical cations through single-electron oxidation by photocatalysis or electro-oxidation. These phosphine radical cations can react with alcohols or carboxylic acids to form the corresponding alkoxyphosphonium or acyloxyphosphonium intermediates, which are very reactive and easily get decomposed. The release of tri-substituted phosphine oxides as a driving force triggers the following nucleophilic substitution. This strategy does not require the use of stoichiometric oxidants and it eludes safety and stability problems. In this review, we summarise the recent advances and discoveries in PIII-assisted direct deoxygenative reactions under photochemical or electrochemical conditions.
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Affiliation(s)
- Xiaoqing Shao
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
| | - Yue Zheng
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
| | - Velayudham Ramadoss
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
| | - Lifang Tian
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
| | - Yahui Wang
- Technical Institute of Fluorochemistry (TIF), Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
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15
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Deazaflavin reductive photocatalysis involves excited semiquinone radicals. Nat Commun 2020; 11:3174. [PMID: 32576821 PMCID: PMC7311442 DOI: 10.1038/s41467-020-16909-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/02/2020] [Indexed: 11/30/2022] Open
Abstract
Flavin-mediated photocatalytic oxidations are established in synthetic chemistry. In contrast, their use in reductive chemistry is rare. Deazaflavins with a much lower reduction potential are even better suited for reductive chemistry rendering also deazaflavin semiquinones as strong reductants. However, no direct evidence exists for the involvement of these radical species in reductive processes. Here, we synthesise deazaflavins with different substituents at C5 and demonstrate their photocatalytic activity in the dehalogenation of p-halogenanisoles with best performance under basic conditions. Mechanistic investigations reveal a consecutive photo-induced electron transfer via the semiquinone form of the deazaflavin as part of a triplet-correlated radical pair after electron transfer from a sacrificial electron donor to the triplet state. A second electron transfer from the excited semiquinone to p-halogenanisoles triggers the final product formation. This study provides first evidence that the reductive power of excited deazaflavin semiquinones can be used in photocatalytic reductive chemistry. Flavins and deazaflavins are well suited for photoredox processes but their application in photoreductions is challenging. Here, the authors provide direct evidence of the high reductive power of excited deazaflavin semiquinones and their application in catalytic photodehalogenations.
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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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17
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18
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Tolba AH, Vávra F, Chudoba J, Cibulka R. Tuning Flavin-Based Photocatalytic Systems for Application in the Mild Chemoselective Aerobic Oxidation of Benzylic Substrates. European J Org Chem 2019. [DOI: 10.1002/ejoc.201901628] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Amal Hassan Tolba
- Department of Organic Chemistry; University of Chemistry and Technology, Prague; Technická 5 166 28 Prague Czech Republic
| | - František Vávra
- Department of Organic Chemistry; University of Chemistry and Technology, Prague; Technická 5 166 28 Prague Czech Republic
| | - Josef Chudoba
- Central Laboratories; University of Chemistry and Technology Prague; Technická 5 166 28 Prague Czech Republic
| | - Radek Cibulka
- Department of Organic Chemistry; University of Chemistry and Technology, Prague; Technická 5 166 28 Prague Czech Republic
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19
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Tagami T, Arakawa Y, Minagawa K, Imada Y. Efficient Use of Photons in Photoredox/Enamine Dual Catalysis with a Peptide-Bridged Flavin-Amine Hybrid. Org Lett 2019; 21:6978-6982. [PMID: 31403307 DOI: 10.1021/acs.orglett.9b02567] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
An isoalloxazine (flavin) ring system and a secondary amine have been integrated through a short peptide linker with the aim of using photons as efficiently as possible in photoredox/enamine dual catalysis. We herein report a peptide-bridged flavin-amine hybrid that can catalyze α-oxyamination of aldehydes with TEMPO under weak blue light irradiation to achieve an extremely high quantum yield of reaction (Φ = 0.80).
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Affiliation(s)
- Takuma Tagami
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan
| | - Yukihiro Arakawa
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan
| | - Keiji Minagawa
- Department of Applied Chemistry, Tokushima University, Minamijosanjima, Tokushima 770-8506, Japan.,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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20
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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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21
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Pokluda A, Kohout M, Chudoba J, Krupička M, Cibulka R. Nitrosobenzene: Reagent for the Mitsunobu Esterification Reaction. ACS OMEGA 2019; 4:5012-5018. [PMID: 31459682 PMCID: PMC6648318 DOI: 10.1021/acsomega.8b03551] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/22/2019] [Indexed: 05/24/2023]
Abstract
Nitrosobenzene has been demonstrated to participate in the Mitsunobu reaction in an analogous manner to dialkyl azodicarboxylates. The protocol using nitrosobenzene and triphenylphosphine (1:1) under mild conditions (0 °C) provides the ester derivatives of aliphatic and aromatic acids using various alcohols in moderate yield and with good enantioselectivity, giving the desired products predominantly with an inversion of configuration. The proposed mechanism, which is analogous to that observed using dialkyl azodicarboxylates, involves a nitrosobenzene-triphenylphosphine adduct and an alkoxytriphenylphosphonium ion and was supported by density functional theory calculations, 31P NMR spectroscopy, and experiments conducted with isotopically labeled substrates.
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Affiliation(s)
- Adam Pokluda
- Department
of Organic Chemistry and Central Laboratories, University
of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Michal Kohout
- Department
of Organic Chemistry and Central Laboratories, University
of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Josef Chudoba
- Department
of Organic Chemistry and Central Laboratories, University
of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Martin Krupička
- Department
of Organic Chemistry and Central Laboratories, University
of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Radek Cibulka
- Department
of Organic Chemistry and Central Laboratories, University
of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic
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22
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Xu Z, Zheng Y, Wang Z, Shao X, Tian L, Wang Y. Triphenylphosphine-assisted dehydroxylative Csp3–N bond formation via electrochemical oxidation. Chem Commun (Camb) 2019; 55:15089-15092. [DOI: 10.1039/c9cc08622f] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A dehydroxylative Csp3–N coupling by electrochemical oxidation with readily available alcohols as substrates and a wide variety of azoles and amides as N-nucleophiles.
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Affiliation(s)
- Zhimin Xu
- Institute of Advanced Synthesis
- School of Chemistry and Molecular Engineering
- Nanjing Tech University
- Nanjing 211816
- China
| | - Yue Zheng
- Institute of Advanced Synthesis
- School of Chemistry and Molecular Engineering
- Nanjing Tech University
- Nanjing 211816
- China
| | - Zhihui Wang
- Institute of Advanced Synthesis
- School of Chemistry and Molecular Engineering
- Nanjing Tech University
- Nanjing 211816
- China
| | - Xiaoqing Shao
- Institute of Advanced Synthesis
- School of Chemistry and Molecular Engineering
- Nanjing Tech University
- Nanjing 211816
- China
| | - Lifang Tian
- Institute of Advanced Synthesis
- School of Chemistry and Molecular Engineering
- Nanjing Tech University
- Nanjing 211816
- China
| | - Yahui Wang
- Institute of Advanced Synthesis
- School of Chemistry and Molecular Engineering
- Nanjing Tech University
- Nanjing 211816
- China
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23
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Zelenka J, Svobodová E, Tarábek J, Hoskovcová I, Boguschová V, Bailly S, Sikorski M, Roithová J, Cibulka R. Combining Flavin Photocatalysis and Organocatalysis: Metal-Free Aerobic Oxidation of Unactivated Benzylic Substrates. Org Lett 2018; 21:114-119. [PMID: 30582822 DOI: 10.1021/acs.orglett.8b03547] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We report a system with ethylene-bridged flavinium salt 2b which catalyzes the aerobic oxidation of toluenes and benzyl alcohols with high oxidation potential ( Eox > +2.5 V vs SCE) to give the corresponding benzoic acids under visible light irradiation. This is caused by the high oxidizing power of excited 2b ( E(2b*) = +2.67 V vs SCE) involved in photooxidation and by the accompanying dark organocatalytic oxygenation provided by the in situ formed flavin hydroperoxide 2b-OOH.
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Affiliation(s)
- Jan Zelenka
- Institute for Molecules and Materials , Radboud University , Heyendaalseweg 135 , 6525 AJ Nijmegen , The Netherlands
| | | | - Ján Tarábek
- Institute of Organic Chemistry and Biochemistry , Academy of Science of the Czech Republic , Flemingovo náměstí 542/2 , 16610 Prague , Czech Republic
| | | | | | | | - Marek Sikorski
- Faculty of Chemistry ; Adam Mickiewicz University in Poznan , Umultowska 89b , 61614 Poznan , Poland
| | - Jana Roithová
- Institute for Molecules and Materials , Radboud University , Heyendaalseweg 135 , 6525 AJ Nijmegen , The Netherlands
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