1
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Smith RE, Dinh LP, Sevov CS. Aminoborate-Catalyzed Reductive Counterreactions for Oxidative Electrosynthetic Transformations. J Org Chem 2024; 89:18550-18555. [PMID: 39621303 DOI: 10.1021/acs.joc.4c02488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2024]
Abstract
Electrooxidative transformations frequently rely on proton reduction as the terminal electron sink. However, this cathodic counterreaction can be slow in organic solvents and can operate at reducing potentials that are incompatible with catalysts and reagents needed for oxidative reactions. We report aminoborate adducts as redox mediators for proton reduction that operate at mild reducing potentials. This reliable cathodic couple ultimately enables successful oxidative organic transformations, including chlorodeborylation, developed herein, and Cu-catalyzed Chan-Lam coupling, reported previously by our group. Pyridinium borate adducts formed during electrooxidative chlorination of aryl trifluoroborates serve as easily reduced complexes (-1.1 V vs Fc/Fc+) to catalyze proton reduction. Reactions that promote the formation of borate adducts result in high yields, operate at low cell potentials, suppress aryl trifluoroborate decomposition, and mitigate electrode passivation. These studies illustrate the utility of Lewis acid-base complexes in cathodic counterreactions and underscore the importance of developing both anodic and cathodic reactions in electrosynthesis.
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Affiliation(s)
- Ryan E Smith
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Long P Dinh
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Christo S Sevov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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2
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Ball MAP, Myers PJ, Ritch GD, Bower JK, Moore CE, Szymczak NK, Zhang S. The Role of Electron Transfer in Copper-Mediated C(sp 2)-H Trifluoromethylation. Angew Chem Int Ed Engl 2024:e202420677. [PMID: 39625452 DOI: 10.1002/anie.202420677] [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: 10/24/2024] [Indexed: 12/14/2024]
Abstract
We report copper(II) and copper(III) trifluoromethyl complexes supported by a pyridinedicarboxamide ligand (L) as a platform for investigating the role of electron transfer in C(sp2)-H trifluoromethylation. While the copper(II) trifluoromethyl complex is unreactive towards (hetero)arenes, the formal copper(III) trifluoromethyl complex performs C(sp2)-H trifluoromethylation of a wide range of (hetero)arenes. Mechanistic studies using the copper(III) trifluoromethyl complex suggest that the mechanism of arene trifluoromethylation is substrate-dependent. When the thermodynamic driving force for electron transfer is high, the reaction proceeds through a previously unidentified single electron transfer (SET) mechanism, where an initial electron transfer occurs between the substrate and oxidant prior to CF3 group transfer. Otherwise, a CF3 radical release/electrophilic aromatic substitution (SEAr) mechanism is followed. These studies provide valuable insights into the role of strong oxidants and potential mechanistic dichotomy in Cu-mediated C(sp2)-H trifluoromethylation.
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Affiliation(s)
- Margaret A P Ball
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, United States
| | - Preston J Myers
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, United States
| | - Grayson D Ritch
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, MI, 48109, United States
| | - Jamey K Bower
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, United States
| | - Curtis E Moore
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, United States
| | - Nathaniel K Szymczak
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, MI, 48109, United States
| | - Shiyu Zhang
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, United States
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3
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Grooms AJ, Huttner RT, Stockwell M, Tadese L, Marcelo IM, Kass A, Badu-Tawiah AK. Programmable C-N Bond Formation through Radical-Mediated Chemistry in Plasma-Microdroplet Fusion. Angew Chem Int Ed Engl 2024:e202413122. [PMID: 39453314 DOI: 10.1002/anie.202413122] [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: 07/12/2024] [Revised: 10/02/2024] [Accepted: 10/23/2024] [Indexed: 10/26/2024]
Abstract
Non-thermal plasma discharge produced in the wake of charged microdroplets is found to facilitate catalyst-free radical mediated hydrazine cross-coupling reactions without the use of external light source, heat, precious metal complex, or trapping agents. A plasma-microdroplet fusion platform is utilized for introduction of hydrazine reagent that undergoes homolytic cleavage forming radical intermediate species. The non-thermal plasma discharge that causes the cleavage originates from a chemically etched silica capillary. The coupling of the radical intermediates gives various products. Plasma-microdroplet fusion occurs online in a programmable reaction platform allowing direct process optimization and product validation via mass spectrometry. The platform is applied herein with a variety of hydrazine substrates, enabling i) self-coupling to form secondary amines with identical N-substitutions, ii) cross-coupling to afford secondary amine with different N-substituents, iii) cross-coupling followed by in situ dehydrogenation to give the corresponding aryl-aldimines with two unique N-substitutions, and iv) cascade heterocyclic carbazole derivatives formation. These unique reactions were made possible in the charged microdroplet environment through our ability to program conditions such as reagent concentration (i. e., flow rate), microdroplet reactivity (i. e., presence or absence of plasma), and reaction timescale (i. e., operational mode of the source). The selected program is implemented in a co-axial spray format, which is found to be advantageous over the conventional one-pot single emitter electrospray-based microdroplet reactions.
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Affiliation(s)
- Alexander J Grooms
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Robert T Huttner
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Mackenzie Stockwell
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Leah Tadese
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Isabella M Marcelo
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Anthony Kass
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Abraham K Badu-Tawiah
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
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4
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Motornov V, Ackermann L. Well-Defined Highly-Coordinated Copper(III) Iodide and Pincer Tris(trifluoromethyl)copper Complexes. Chemistry 2024; 30:e202401791. [PMID: 38976449 DOI: 10.1002/chem.202401791] [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: 06/24/2024] [Revised: 07/07/2024] [Accepted: 07/08/2024] [Indexed: 07/10/2024]
Abstract
Copper(III) iodide and bromide complexes representing a unique combination of highly-coordinated metal and soft polarizable anions were synthesized and fully characterized, including X-ray crystallography. Ligand substitution in well-defined highly-coordinated copper complex PyCu(CF3)3 with pincer ligands was achieved to give formally octahedral copper(III) complexes.
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Affiliation(s)
- Vladimir Motornov
- Wöhler-Research Institute for Sustainable Chemistry (WISCh), Georg-August-Universität, Tammannstrasse 2, Göttingen, 37077, Germany
| | - Lutz Ackermann
- Wöhler-Research Institute for Sustainable Chemistry (WISCh), Georg-August-Universität, Tammannstrasse 2, Göttingen, 37077, Germany
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5
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Zhao Q, Chen Z, Soler J, Chen X, Rui J, Ji NT, Yu QE, Yang Y, Garcia-Borràs M, Huang X. Engineering non-haem iron enzymes for enantioselective C(sp3)-F bond formation via radical fluorine transfer. NATURE SYNTHESIS 2024; 3:958-966. [PMID: 39364063 PMCID: PMC11446476 DOI: 10.1038/s44160-024-00507-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 02/21/2024] [Indexed: 10/05/2024]
Abstract
In recent years there has been a surge in the development of methods for the synthesis of organofluorine compounds. However, enzymatic methods for C-F bond formation have been limited to nucleophilic fluoride substitution. Here, we report the incorporation of iron-catalysed radical fluorine transfer, a reaction mechanism that is not used in naturally occurring enzymes, into enzymatic catalysis for the development of biocatalytic enantioselective C(sp 3)-F bond formation. Using this strategy, we repurposed (S)-2-hydroxypropylphosphonate epoxidase from Streptomyces viridochromogenes (SvHppE) to catalyse an N-fluoroamide directed C(sp 3)-H fluorination. Directed evolution has enabled SvHppE to be optimized, forming diverse chiral benzylic fluoride products with turnover numbers of up to 180 and with excellent enantiocontrol (up to 94% e.e.). Mechanistic investigations showed that the N-F bond activation is the rate-determining step, and the strong preference for fluorination in the presence of excess NaN3 can be attributed to the spatial proximity of the carbon-centered radical to the iron-bound fluoride.
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Affiliation(s)
- Qun Zhao
- School of Biotechnology, Jiangnan University, Wuxi 214122, P. R. China
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Zhenhong Chen
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jordi Soler
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Girona E-17071, Catalonia, Spain
| | - Xiahe Chen
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Key Laboratory of Green Chemistry-Synthesis Technology of Zhejiang Province, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Jinyan Rui
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Nathan Tianlin Ji
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | | | - Yunfang Yang
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Key Laboratory of Green Chemistry-Synthesis Technology of Zhejiang Province, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China
| | - Marc Garcia-Borràs
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Girona E-17071, Catalonia, Spain
| | - Xiongyi Huang
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
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6
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De Tovar J, Leblay R, Wang Y, Wojcik L, Thibon-Pourret A, Réglier M, Simaan AJ, Le Poul N, Belle C. Copper-oxygen adducts: new trends in characterization and properties towards C-H activation. Chem Sci 2024; 15:10308-10349. [PMID: 38994420 PMCID: PMC11234856 DOI: 10.1039/d4sc01762e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 05/11/2024] [Indexed: 07/13/2024] Open
Abstract
This review summarizes the latest discoveries in the field of C-H activation by copper monoxygenases and more particularly by their bioinspired systems. This work first describes the recent background on copper-containing enzymes along with additional interpretations about the nature of the active copper-oxygen intermediates. It then focuses on relevant examples of bioinorganic synthetic copper-oxygen intermediates according to their nuclearity (mono to polynuclear). This includes a detailed description of the spectroscopic features of these adducts as well as their reactivity towards the oxidation of recalcitrant Csp3 -H bonds. The last part is devoted to the significant expansion of heterogeneous catalytic systems based on copper-oxygen cores (i.e. within zeolite frameworks).
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Affiliation(s)
- Jonathan De Tovar
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire Grenoble France
| | - Rébecca Leblay
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Yongxing Wang
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Laurianne Wojcik
- Université de Brest, Laboratoire de Chimie, Electrochimie Moléculaires et Chimie Analytique Brest France
| | | | - Marius Réglier
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - A Jalila Simaan
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Nicolas Le Poul
- Université de Brest, Laboratoire de Chimie, Electrochimie Moléculaires et Chimie Analytique Brest France
| | - Catherine Belle
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire Grenoble France
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7
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Atkins AP, Dean AC, Lennox AJJ. Benzylic C(sp 3)-H fluorination. Beilstein J Org Chem 2024; 20:1527-1547. [PMID: 39015617 PMCID: PMC11250007 DOI: 10.3762/bjoc.20.137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 06/26/2024] [Indexed: 07/18/2024] Open
Abstract
The selective fluorination of C(sp3)-H bonds is an attractive target, particularly for pharmaceutical and agrochemical applications. Consequently, over recent years much attention has been focused on C(sp3)-H fluorination, and several methods that are selective for benzylic C-H bonds have been reported. These protocols operate via several distinct mechanistic pathways and involve a variety of fluorine sources with distinct reactivity profiles. This review aims to give context to these transformations and strategies, highlighting the different tactics to achieve fluorination of benzylic C-H bonds.
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Affiliation(s)
| | - Alice C Dean
- University of Bristol, School of Chemistry, Bristol, BS8 1TS, U.K.
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8
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Joven-Sancho D, Echeverri A, Saffon-Merceron N, Contreras-García J, Nebra N. An Organocopper(III) Fluoride Triggering C-CF 3 Bond Formation. Angew Chem Int Ed Engl 2024; 63:e202319412. [PMID: 38147576 DOI: 10.1002/anie.202319412] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 12/22/2023] [Accepted: 12/22/2023] [Indexed: 12/28/2023]
Abstract
Copper(III) fluorides are catalytically competent, yet elusive, intermediates in cross-coupling. The synthesis of [PPh4 ][CuIII (CF3 )3 F] (2), the first stable (isolable) CuIII -F, was accomplished via chloride addition to [CuIII (CF3 )3 (py)] (1) yielding [PPh4 ][CuIII (CF3 )3 Cl(py)] (1⋅Cl), followed by treatment with AgF. The CuIII halides 1⋅Cl and 2 were fully characterized using nuclear magnetic resonance (NMR) spectroscopy, single crystal X-ray diffraction (Sc-XRD) and elemental analysis (EA). Complex 2 proved capable of forging C-CF3 bonds from silyl-capped alkynes. In-depth mechanistic studies combining probes, theoretical calculations, trapping of intermediate 4a ([PPh4 ][CuIII (CF3 )3 (C≡CPh)]) and radical tests unveil the key role of the CuIII acetylides that undergo facile 2e- reductive elimination furnishing the trifluoromethylated alkynes (RC≡CCF3 ), which are industrially relevant synthons in drug discovery, pharma and agrochemistry.
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Affiliation(s)
- Daniel Joven-Sancho
- Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université Paul Sabatier, CNRS, 118 Route de Narbonne, 31062, Toulouse, France
| | - Andrea Echeverri
- Laboratoire de Chimie Théorique (LCT), Sorbonne Université, CNRS, 4, Place Jussieu, 75005, Paris, France
| | - Nathalie Saffon-Merceron
- Institut de Chimie de Toulouse ICT-UAR2599, Université Paul Sabatier, CNRS, 31062, Toulouse Cedex, France
| | - Julia Contreras-García
- Laboratoire de Chimie Théorique (LCT), Sorbonne Université, CNRS, 4, Place Jussieu, 75005, Paris, France
| | - Noel Nebra
- Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université Paul Sabatier, CNRS, 118 Route de Narbonne, 31062, Toulouse, France
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9
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Jeong D, Lee Y, Lee Y, Kim K, Cho J. Synthesis, Characterization, and Reactivity of a Highly Oxidative Mononuclear Manganese(IV)-Bis(Fluoro) Complex. J Am Chem Soc 2024; 146:4172-4177. [PMID: 38311844 DOI: 10.1021/jacs.3c13324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
Recently, transition-metal terminal nonoxo complexes have shown a remarkable ability to activate and functionalize C-H bonds via proton-coupled electron transfer (PCET). Here we report the first example of a mononuclear manganese(IV) bis(fluoro) complex bearing a tetradentate pyridinophane ligand, [MnIV(TBDAP)(F)2]2+ (3), with an X-ray single crystal structure and physicochemical characterization. The manganese(IV) bis(fluoro) complex has a very high reduction potential of 1.61 V vs SCE, thereby enabling the four-electron oxidation of mesitylene to 3,5-dimethylbenzaldehyde. Kinetic studies, including the kinetic isotope effect and employment of other toluene derivatives, reveal the electron transfer (ET)-driven PCET in the C-H bond activation of mesitylene by 3. This novel metal halide intermediate would be prominently valuable for expanding transition-metal halide chemistry.
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Affiliation(s)
- Donghyun Jeong
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Yujeong Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Yuri Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Kyungmin Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Jaeheung Cho
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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10
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Atkins AP, Chaturvedi AK, Tate JA, Lennox AJJ. Pulsed electrolysis: enhancing primary benzylic C(sp 3)-H nucleophilic fluorination. Org Chem Front 2024; 11:802-808. [PMID: 38298566 PMCID: PMC10825853 DOI: 10.1039/d3qo01865b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 12/09/2023] [Indexed: 02/02/2024]
Abstract
Electrosynthesis is an efficient and powerful tool for the generation of elusive reactive intermediates. The application of alternative electrolysis waveforms provides a new level of control for dynamic redox environments. Herein, we demonstrate that pulsed electrolysis provides a favourable environment for the generation and fluorination of highly unstable primary benzylic cations from C(sp3)-H bonds. By introduction of a toff period, we propose this waveform modulates the electrical double layer to improve mass transport and limit over-oxidation.
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Affiliation(s)
- Alexander P Atkins
- School of Chemistry, University of Bristol Cantock's Close BS8 1TS Bristol UK
| | - Atul K Chaturvedi
- School of Chemistry, University of Bristol Cantock's Close BS8 1TS Bristol UK
| | - Joseph A Tate
- Jealott's Hill International Research Centre, Syngenta Jealott's Hill Bracknell RG426EY UK
| | - Alastair J J Lennox
- School of Chemistry, University of Bristol Cantock's Close BS8 1TS Bristol UK
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11
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Schneider JE, Anderson JS. Reconciling Imbalanced and Nonadiabatic Reactivity in Transition Metal-Oxo-Mediated Concerted Proton Electron Transfer (CPET). J Phys Chem Lett 2023; 14:9548-9555. [PMID: 37856336 DOI: 10.1021/acs.jpclett.3c02318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Recently, there have been several experimental demonstrations of how the rates of concerted proton electron transfer (CPET) are affected by stepwise thermodynamic parameters of only proton (ΔG°PT) or electron (ΔG°ET) transfer. Semiclassical structure-activity relationships have been invoked to rationalize these linear free energy relationships, but it is not clear how they would manifest in a nonadiabatic reaction. Using density functional theory calculations, we demonstrate how a decrease in ΔG°PT can lead to transition state imbalance in a nonadiabatic framework. We then use these calculations to anchor a theoretical model that reproduces experimental trends with ΔG°PT and ΔG°ET. Our results reconcile predictions from semiclassical transition state theory with models that treat proton transfer quantum mechanically in CPET reactivity, make new predictions about the importance of basicity for uphill CPET reactions, and suggest similar treatments may be possible for other nonadiabatic reactions.
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Affiliation(s)
- Joseph E Schneider
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - John S Anderson
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
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12
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Yadav V, Wen L, Yadav S, Siegler MA, Goldberg DP. Selective Radical Transfer in a Series of Nonheme Iron(III) Complexes. Inorg Chem 2023; 62:17830-17842. [PMID: 37857315 PMCID: PMC11296666 DOI: 10.1021/acs.inorgchem.3c02617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
A series of nonheme iron complexes, FeIII(BNPAPh2O)(Lax)(Leq) (Lax/eq = N3-, NCS-, NCO-, and Cl-) have been synthesized using the previously reported BNPAPh2O- ligand. The ferrous analogs FeII(BNPAPh2O)(Lax) (Lax = N3-, NCS-, and NCO-) were also prepared. The complexes were structurally characterized using single crystal X-ray diffraction, which shows that all the FeIII complexes are six-coordinate, with one anionic ligand (Lax) in the H-bonding axial site and the other anionic ligand (Leq) in the equatorial plane, cis to the Lax ligand. The reaction of FeIII(BNPAPh2O-)(Lax)(Leq) with Ph3C• shows that one ligand is selectively transferred in each case. A selectivity trend emerges that shows •N3 is the most favored for transfer in each case to the carbon radical, whereas Cl• is the least favored. The NCO and NCS ligands showed an intermediate propensity for radical transfer, with NCS > NCO. The overall order of selectivity is N3 > NCS > NCO > Cl. In addition, we also demonstrated that H-bonding has a small effect on governing product selectivity by using a non-H-bonded ligand (DPAPh2O-). This study demonstrates the inherent radical transfer selectivity of nonhydroxo-ligated nonheme iron(III) complexes, which could be useful for efforts in synthetic and (bio)catalytic C-H functionalization.
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Affiliation(s)
- Vishal Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Lyupeng Wen
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Sudha Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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13
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Demonti L, Joven-Sancho D, Nebra N. Cross-Coupling Reactions Enabled by Well-Defined Ag(III) Compounds: Main Focus on Aromatic Fluorination and Trifluoromethylation. CHEM REC 2023; 23:e202300143. [PMID: 37338273 DOI: 10.1002/tcr.202300143] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/31/2023] [Indexed: 06/21/2023]
Abstract
AgIII compounds are considered strong oxidizers of difficult handling. Accordingly, the involvement of Ag catalysts in cross-coupling via 2e- redox sequences is frequently discarded. Nevertheless, organosilver(III) compounds have been authenticated using tetradentate macrocycles or perfluorinated groups as supporting ligands, and since 2014, first examples of cross-coupling enabled by AgI /AgIII redox cycles saw light. This review collects the most relevant contributions to this field, with main focus on aromatic fluorination/perfluoroalkylation and the identification of AgIII key intermediates. Pertinent comparison between the activity of AgIII RF compounds in aryl-F and aryl-CF3 couplings vs. the one shown by its CuIII RF and AuIII RF congeners is herein disclosed, thus providing a more profound picture on the scope of these transformations and the pathways commonly associated to C-RF bond formations enabled by coinage metals.
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Affiliation(s)
- Luca Demonti
- Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA)., Université Paul Sabatier, CNRS., 118 Route de Narbonne, 31062, Toulouse, France)
| | - Daniel Joven-Sancho
- Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA)., Université Paul Sabatier, CNRS., 118 Route de Narbonne, 31062, Toulouse, France)
| | - Noel Nebra
- Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA)., Université Paul Sabatier, CNRS., 118 Route de Narbonne, 31062, Toulouse, France)
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14
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Blythe IM, Xu J, Fernandez Odell JS, Kampf JW, Bowring MA, Sanford MS. Characterization and Reactivity of Copper(II) and Copper(III) σ-Aryl Intermediates in Aminoquinoline-Directed C-H Functionalization. J Am Chem Soc 2023; 145:18253-18259. [PMID: 37552536 DOI: 10.1021/jacs.3c00914] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
Over the past decade, numerous reports have focused on the development and applications of Cu-mediated C-H functionalization reactions; however, to date, little is known about the Cu intermediates involved in these transformations. This paper details the observation and characterization of CuII and CuIII intermediates in aminoquinoline-directed C(sp2)-H functionalization of a fluoroarene substrate. An initial C(sp2)-H activation at CuII occurs at room temperature to afford an isolable anionic cyclometalated CuII complex. This complex undergoes single-electron oxidation with ferrocenium or AgI salts under mild conditions (5 min at room temperature) to afford C(sp2)-C(sp2) or C(sp2)-NO2 coupling products. Spectroscopic studies implicate the formation of a transient diamagnetic CuIII-σ-aryl intermediate that undergoes either (i) a second C(sp2)-H activation at CuIII followed by C-C bond-forming reductive elimination or (ii) reaction with a NO2- nucleophile and C(sp2)-NO2 coupling.
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Affiliation(s)
- Isaac M Blythe
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Jingtong Xu
- Department of Chemistry, Reed College, 3203 Woodstock Boulevard, Portland, Oregon 97202, United States
| | - Joaquin S Fernandez Odell
- Department of Chemistry, Reed College, 3203 Woodstock Boulevard, Portland, Oregon 97202, United States
| | - Jeff W Kampf
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
| | - Miriam A Bowring
- Department of Chemistry, Reed College, 3203 Woodstock Boulevard, Portland, Oregon 97202, United States
| | - Melanie S Sanford
- Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, Michigan 48109, United States
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