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Liu D, Hazra A, Liu X, Maity R, Tan T, Luo L. CdS Quantum Dot Gels as a Direct Hydrogen Atom Transfer Photocatalyst for C-H Activation. Angew Chem Int Ed Engl 2024; 63:e202403186. [PMID: 38900647 DOI: 10.1002/anie.202403186] [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: 02/14/2024] [Revised: 05/13/2024] [Accepted: 06/19/2024] [Indexed: 06/22/2024]
Abstract
Here, we report CdS quantum dot (QD) gels, a three-dimensional network of interconnected CdS QDs, as a new type of direct hydrogen atom transfer (d-HAT) photocatalyst for C-H activation. We discovered that the photoexcited CdS QD gel could generate various neutral radicals, including α-amido, heterocyclic, acyl, and benzylic radicals, from their corresponding stable molecular substrates, including amides, thio/ethers, aldehydes, and benzylic compounds. Its C-H activation ability imparts a broad substrate and reaction scope. The mechanistic study reveals that this reactivity is intrinsic to CdS materials, and the neutral radical generation did not proceed via the conventional sequential electron transfer and proton transfer pathway. Instead, the C-H bonds are activated by the photoexcited CdS QD gel via a d-HAT mechanism. This d-HAT mechanism is supported by the linear correlation between the logarithm of the C-H bond activation rate constant and the C-H bond dissociation energy (BDE) with a Brønsted slope α=0.5. Our findings expand the currently limited direct hydrogen atom transfer photocatalysis toolbox and provide new possibilities for photocatalytic C-H activation.
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Affiliation(s)
- Daohua Liu
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202
| | - Atanu Hazra
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202
| | - Xiaolong Liu
- Laboratory of Theoretical and Computational Nanoscience, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, 100190, China
| | - Rajendra Maity
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202
| | - Ting Tan
- Laboratory of Theoretical and Computational Nanoscience, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing, 100190, China
| | - Long Luo
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI 48202
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2
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Zhang Z, Poletti L, Leonori D. A Radical Strategy for the Alkylation of Amides with Alkyl Halides by Merging Boryl Radical-Mediated Halogen-Atom Transfer and Copper Catalysis. J Am Chem Soc 2024; 146:22424-22430. [PMID: 39087940 DOI: 10.1021/jacs.4c05487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
Amide alkylation is a fundamental process in organic chemistry. However, the low nucleophilicity of amides means that divergent coupling with alkyl electrophiles is often not achievable. To circumvent this reactivity challenge, individual amine synthesis followed by amidation with standard coupling agents is generally required. Herein, we demonstrate a radical solution to this challenge by using an amine-borane complex and copper catalysis under oxidative conditions. While borohydride reagents are generally used as reducing agents in ionic chemistry, their conversion into amine-ligated boryl radicals diverts their reactivity toward halogen-atom transfer. This enables the conversion of alkyl halides into the corresponding alkyl radicals for amide functionalization via copper catalysis. The process is applicable to the N-alkylation of primary amides employing unactivated alkyl iodides and bromides, and it was also showcased in the late-state functionalization of both complex amide- and halide-containing drugs.
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Affiliation(s)
- Zhenhua Zhang
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, Aachen 52056, Germany
| | - Lorenzo Poletti
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, Aachen 52056, Germany
| | - Daniele Leonori
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, Aachen 52056, Germany
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3
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Wojdyla Z, Srnec M. Radical ligand transfer: mechanism and reactivity governed by three-component thermodynamics. Chem Sci 2024; 15:8459-8471. [PMID: 38846394 PMCID: PMC11151871 DOI: 10.1039/d4sc01507j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 04/19/2024] [Indexed: 06/09/2024] Open
Abstract
Here, we demonstrate that the relationship between reactivity and thermodynamics in radical ligand transfer chemistry can be understood if this chemistry is dissected as concerted ion-electron transfer (cIET). Namely, we investigate radical ligand transfer reactions from the perspective of thermodynamic contributions to the reaction barrier: the diagonal effect of the free energy of the reaction, and the off-diagonal effect resulting from asynchronicity and frustration, which we originally derived from the thermodynamic cycle for concerted proton-electron transfer (cPET). This study on the OH transfer reaction shows that the three-component thermodynamic model goes beyond cPET chemistry, successfully capturing the changes in radical ligand transfer reactivity in a series of model FeIII-OH⋯(diflouro)cyclohexadienyl systems. We also reveal the decisive role of the off-diagonal thermodynamics in determining the reaction mechanism. Two possible OH transfer mechanisms, in which electron transfer is coupled with either OH- and OH+ transfer, are associated with two competing thermodynamic cycles. Consequently, the operative mechanism is dictated by the cycle yielding a more favorable off-diagonal effect on the barrier. In line with this thermodynamic link to the mechanism, the transferred OH group in OH-/electron transfer retains its anionic character and slightly changes its volume in going from the reactant to the transition state. In contrast, OH+/electron transfer develops an electron deficiency on OH, which is evidenced by an increase in charge and a simultaneous decrease in volume. In addition, the observations in the study suggest that an OH+/electron transfer reaction can be classified as an adiabatic radical transfer, and the OH-/electron transfer reaction as a less adiabatic ion-coupled electron transfer.
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Affiliation(s)
- Zuzanna Wojdyla
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences Dolejškova 3 Prague 8 18223 Czech Republic
| | - Martin Srnec
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences Dolejškova 3 Prague 8 18223 Czech Republic
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Müller AV, Ahmad S, Sirlin JT, Ertem MZ, Polyansky DE, Grills DC, Meyer GJ, Sampaio RN, Concepcion JJ. Reduction of CO to Methanol with Recyclable Organic Hydrides. J Am Chem Soc 2024; 146:10524-10536. [PMID: 38507247 DOI: 10.1021/jacs.3c14605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
The reaction steps for the selective conversion of a transition metal carbonyl complex to a hydroxymethyl complex that releases methanol upon irradiation with visible light have been successfully quantified in acetonitrile solution with dihydrobenzimidazole organic hydride reductants. Dihydrobenzimidazole reductants have been shown to be inactive toward H2 generation in the presence of a wide range of proton sources and have been regenerated electrochemically or photochemically. Specifically, the reaction of cis-[Ru(bpy)2(CO)2]2+ (bpy = 2,2'-bipyridine) with one equivalent of a dihydrobenzimidazole quantitatively yields a formyl complex, cis-[Ru(bpy)2(CO)(CHO)]+, and the corresponding benzimidazolium on a seconds time scale. Kinetic experiments revealed a first-order dependence on the benzimidazole hydride concentration and an unusually large kinetic isotope effect, inconsistent with direct hydride transfer and more likely to occur by an electron transfer-proton-coupled electron transfer (EΤ-PCET) or related mechanism. Further reduction/protonation of cis-[Ru(bpy)2(CO)(CHO)]+ with two equivalents of the organic hydride yields the hydroxymethyl complex cis-[Ru(bpy)2(CO)(CH2OH)]+. Visible light excitation of cis-[Ru(bpy)2(CO)(CH2OH)]+ in the presence of excess organic hydride was shown to yield free methanol. Identification and quantification of methanol as the sole CO reduction product was confirmed by 1H NMR spectroscopy and gas chromatography. The high selectivity and mild reaction conditions suggest a viable approach for methanol production from CO, and from CO2 through cascade catalysis, with renewable organic hydrides that bear similarities to Nature's NADPH/NADP+.
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Affiliation(s)
- Andressa V Müller
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Shahbaz Ahmad
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Jake T Sirlin
- Department of Chemistry, University of North Carolina Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Mehmed Z Ertem
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Dmitry E Polyansky
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - David C Grills
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Renato N Sampaio
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
- Department of Chemistry, University of North Carolina Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Javier J Concepcion
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
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5
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Groff BD, Koronkiewicz B, Mayer JM. Polar Effects in Hydrogen Atom Transfer Reactions from a Proton-Coupled Electron Transfer (PCET) Perspective: Abstractions from Toluenes. J Org Chem 2023; 88:16259-16269. [PMID: 37978890 PMCID: PMC10841608 DOI: 10.1021/acs.joc.3c01748] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Rate constants for hydrogen atom transfer (HAT) reactions of substituted toluenes with tert-butyl, tert-butoxy, and tert-butylperoxyl radicals are reanalyzed here using the free energies of related proton transfer (PT) and electron transfer (ET) reactions, calculated from an extensive set of compiled or estimated pKa and E° values. The Eyring activation energies ΔGHAT‡ do not correlate with the relatively constant ΔG°HAT, but do correlate close-to-linearly with ΔG°PT and ΔG°ET. The slopes of correlations are similar for the three radicals except that the tBu• barriers shift in the opposite direction from the oxyl radical barriers─a clear example of the qualitative "polar effect" in HAT reactions. When cast quantitatively in free energy terms (ΔGHAT‡ vs ΔG°PT/ET), this effect is very small, only 5-10% of the typical Bell-Evans-Polanyi (BEP) effect of changing ΔG°HAT. This analysis also highlights connections between polar effects and the concepts of "asynchronous" or "imbalanced" HAT reactions in which the PT and ET components of ΔG°HAT contribute differently to the barrier. Finally, these observations are discussed in light of the traditional explanations of polar effects and the potential for a rubric that could predict the extent to which contra-thermodynamic selectivity may be achieved in HAT reactions.
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Affiliation(s)
- Benjamin D. Groff
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Brian Koronkiewicz
- Current Address: Johns Hopkins University Applied Physics Laboratory, 11091 Johns Hopkins Rd, Laurel, MD 20723
| | - James M. Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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6
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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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7
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Meger FS, Murphy JA. Recent Advances in C-H Functionalisation through Indirect Hydrogen Atom Transfer. Molecules 2023; 28:6127. [PMID: 37630379 PMCID: PMC10459052 DOI: 10.3390/molecules28166127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/09/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
The functionalisation of C-H bonds has been an enormous achievement in synthetic methodology, enabling new retrosynthetic disconnections and affording simple synthetic equivalents for synthons. Hydrogen atom transfer (HAT) is a key method for forming alkyl radicals from C-H substrates. Classic reactions, including the Barton nitrite ester reaction and Hofmann-Löffler-Freytag reaction, among others, provided early examples of HAT. However, recent developments in photoredox catalysis and electrochemistry have made HAT a powerful synthetic tool capable of introducing a wide range of functional groups into C-H bonds. Moreover, greater mechanistic insights into HAT have stimulated the development of increasingly site-selective protocols. Site-selectivity can be achieved through the tuning of electron density at certain C-H bonds using additives, a judicious choice of HAT reagent, and a solvent system. Herein, we describe the latest methods for functionalizing C-H/Si-H/Ge-H bonds using indirect HAT between 2018-2023, as well as a critical discussion of new HAT reagents, mechanistic aspects, substrate scopes, and background contexts of the protocols.
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Affiliation(s)
- Filip S. Meger
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, 16 Avinguda dels Països Catalans, 43007 Tarragona, Catalonia, Spain
| | - John A. Murphy
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
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8
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Teindl K, Patrick BO, Nichols EM. Linear Free Energy Relationships and Transition State Analysis of CO 2 Reduction Catalysts Bearing Second Coordination Spheres with Tunable Acidity. J Am Chem Soc 2023; 145:17176-17186. [PMID: 37499125 DOI: 10.1021/jacs.3c03919] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
In molecular catalysts, protic functional groups in the secondary coordination sphere (SCS) work in conjunction with an exogenous acid to relay protons to the active site of electrochemical CO2 reduction; however, it is not well understood how the acidity of the SCS and exogenous acid together determine the kinetics of catalytic turnover. To evaluate the relative contributions of proton transfer driving forces, we synthesized a series of modular iron tetraphenylporphyrin electrocatalysts bearing SCS amides of tunable pKa (17.6 to 20.0 in dimethyl sulfoxide (DMSO)) and employed phenols of variable acidity (15.3 to 19.1) as exogenous acids. This system allowed us to (1) evaluate contributions from proton transfer driving forces associated with either the SCS or exogenous acid and (2) obtain mechanistic insights into CO2 reduction as a function of pKa. A series of linear free-energy relationships show that kinetics become increasingly sensitive to variations in SCS pKa when more acidic exogenous acids are used (0.82 ≥ Brønsted α ≥ 0.13), as well as to variations in exogenous acid pKa when SCS acidity is increased (0.62 ≥ Brønsted α ≥ 0.32). An Eyring analysis suggests that the rate-determining transition state becomes more ordered with decreasing SCS acidity, which is consistent with the proposal that SCS acidity modulates charge accumulation and solvation at the rate-limiting transition state. Together, these insights enable the optimization of activation barriers as a function of both SCS and exogenous acid pKa and can further guide the rational design of electrocatalytic systems wherein contributions from all participants in a proton relay are considered.
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Affiliation(s)
- Kaeden Teindl
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Brian O Patrick
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Eva M Nichols
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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9
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Chang L, Wang S, An Q, Liu L, Wang H, Li Y, Feng K, Zuo Z. Resurgence and advancement of photochemical hydrogen atom transfer processes in selective alkane functionalizations. Chem Sci 2023; 14:6841-6859. [PMID: 37389263 PMCID: PMC10306100 DOI: 10.1039/d3sc01118f] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 05/11/2023] [Indexed: 07/01/2023] Open
Abstract
The selective functionalization of alkanes has long been recognized as a prominent challenge and an arduous task in organic synthesis. Hydrogen atom transfer (HAT) processes enable the direct generation of reactive alkyl radicals from feedstock alkanes and have been successfully employed in industrial applications such as the methane chlorination process, etc. Nevertheless, challenges in the regulation of radical generation and reaction pathways have created substantial obstacles in the development of diversified alkane functionalizations. In recent years, the application of photoredox catalysis has provided exciting opportunities for alkane C-H functionalization under extremely mild conditions to trigger HAT processes and achieve radical-mediated functionalizations in a more selective manner. Considerable efforts have been devoted to building more efficient and cost-effective photocatalytic systems for sustainable transformations. In this perspective, we highlight the recent development of photocatalytic systems and provide our views on current challenges and future opportunities in this field.
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Affiliation(s)
- Liang Chang
- School of Pharmacy, Nanjing University of Chinese Medicine Nanjing 210023 China
| | - Shun Wang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 China
| | - Qing An
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 China
| | - Linxuan Liu
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 China
| | - Hexiang Wang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 China
| | - Yubo Li
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 China
| | - Kaixuan Feng
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 China
| | - Zhiwei Zuo
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences Shanghai 200032 China
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10
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Fu YH, Jia T, Shen GB, Zhu XQ. Quantitative evaluation of H-donating abilities of C(sp 3)-H bonds of nitrogen-containing heterocycles in hydrogen atom transfer reaction. RSC Adv 2023; 13:16023-16033. [PMID: 37260565 PMCID: PMC10227530 DOI: 10.1039/d3ra02211k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 05/10/2023] [Indexed: 06/02/2023] Open
Abstract
Nitrogen-containing heterocycles are an important class of antioxidants, and their reactivity and selectivity in hydrogen atom reactions have attracted significant interest from chemists. In this work, the kinetics of hydrogen atom transfer reactions from C(sp3)-H bonds of 28 nitrogen-containing heterocycles, oxygen-containing heterocycles, alicyclic amines and cycloalkanes, which were denoted as XH, to the CumO˙ radical, were investigated. The characteristic physical parameter of the substrate, i.e., the thermo-kinetic parameter ΔG≠o(XH), was determined using the kinetic equation [ΔG≠XH/Y = ΔG≠o(XH) + ΔG≠o(Y)] to quantitatively evaluate the H-donating ability of XH. The effects of the substrate structure, substituent attached to the nitrogen atom, and ring size on the H-donating ability were discussed carefully. By comparing the H-donating abilities of cycloalkanes, alicyclic amines and nitrogen/oxygen-containing heterocycles, the influence of the introduction of N, O, or carbonyl groups in the carbon ring on the H-donating ability of C(sp3)-H bond was determined. The electronic, steric and stereo-electronic effects of the groups were also discussed. Herein, we not only quantitatively determined the H-donating ability of the substrate, but also provided ideas for the synthesis of new antioxidants.
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Affiliation(s)
- Yan-Hua Fu
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology Anyang Henan 455000 China
| | - Taixuan Jia
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology Anyang Henan 455000 China
| | - Guang-Bin Shen
- School of Medical Engineering, Jining Medical University Jining Shandong 272000 P. R. China
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University Tianjin 300071 China
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Wang Y, Zhao L, Liu S, Ji G, He C, Tang Y, Duan C. Mixed-Component Metal-Organic Framework for Boosting Synergistic Photoactivation of C(sp 3)-H and Oxygen. ACS APPLIED MATERIALS & INTERFACES 2023; 15:16744-16754. [PMID: 36943723 DOI: 10.1021/acsami.2c23245] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Synergistic catalysis is an efficient and powerful strategy for simultaneously activating reactants by multiple active sites to promote the efficiency of difficult and challenging catalytic reactions. Meanwhile, enzymes with multi-active-site synergistic catalytic properties possessing high efficiency and high selectivity have become the goal pursued in the field of catalytic chemistry in recent years. Metal-organic frameworks (MOFs), as an effective heterogeneous catalytic platform, that can integrate multiple active sites for synergistic catalysis like enzymatic systems have recently attracted interest. Herein, we report a doubly interpenetrated metal-organic framework with dual active sites, MnIII-porphyrin sites to directly activate molecular oxygen and fluoren-9-one sites to produce a hydrogen atom transfer (HAT) agent by the proton-coupled electron transfer (PCET) process to simultaneously activate inert C(sp3)-H bonds for efficient inert C(sp3)-H bond oxidation under mild conditions. The bifunctional mixed-component MOF structure forced the two catalytic sites closer together to a more suitable distance, exhibiting high photocatalytic activity for inert C(sp3)-H bond oxidation with almost unique selectivity under mild conditions. The density functional theory (DFT) calculation of free energy during the whole catalytic process demonstrated that it is likely that the synergistic catalytic process occurred in the interframework to accelerate the catalytic reaction. The assembling mixed-component MOF for synergistic catalysis would be a prospective approach for the inert C(sp3)-H photoactivation and functionalization.
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Affiliation(s)
- Yefei Wang
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China
| | - Liang Zhao
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China
| | - Songtao Liu
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China
| | - Guanfeng Ji
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China
| | - Cheng He
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China
| | - Yang Tang
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China
| | - Chunying Duan
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China
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Yang Y, Volpato GA, Rossin E, Peruffo N, Tumbarello F, Nicoletti C, Bonetto R, Paoloni L, Umari P, Colusso E, Dell'Amico L, Berardi S, Collini E, Caramori S, Agnoli S, Sartorel A. Photoelectrochemical C-H Activation Through a Quinacridone Dye Enabling Proton-Coupled Electron Transfer. CHEMSUSCHEM 2023; 16:e202201980. [PMID: 36507568 DOI: 10.1002/cssc.202201980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/30/2022] [Indexed: 06/17/2023]
Abstract
Dye-sensitized photoanodes for C-H activation in organic substrates are assembled by vacuum sublimation of a commercially available quinacridone (QNC) dye in the form of nanosized rods onto fluorine-doped tin oxide (FTO), TiO2 , and SnO2 slides. The photoanodes display extended absorption in the visible range (450-600 nm) and ultrafast photoinduced electron injection (<1 ps, as revealed by transient absorption spectroscopy) of the QNC dye into the semiconductor. The proton-coupled electron-transfer reactivity of QNC is exploited for generating a nitrogen-based radical as its oxidized form, which is competent in C-H bond activation. The key reactivity parameter is the bond-dissociation free energy (BDFE) associated with the N⋅/N-H couple in QNC of 80.5±2.3 kcal mol-1 , which enables hydrogen atom abstraction from allylic or benzylic C-H moieties. A photoelectrochemical response is indeed observed for organic substrates characterized by C-H bonds with BDFE below the 80.5 kcal mol-1 threshold, such as γ-terpinene, xanthene, or dihydroanthracene. This work provides a rational, mechanistically oriented route to the design of dye-sensitized photoelectrodes for selective organic transformations.
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Affiliation(s)
- Yunshuo Yang
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Giulia Alice Volpato
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Elena Rossin
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Nicola Peruffo
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Francesco Tumbarello
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Catia Nicoletti
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Ruggero Bonetto
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Lorenzo Paoloni
- Department of Physics and Astronomy, University of Padova, via F. Marzolo 8, 35131, Padova, Italy
| | - Paolo Umari
- Department of Physics and Astronomy, University of Padova, via F. Marzolo 8, 35131, Padova, Italy
| | - Elena Colusso
- Department of Industrial Engineering and INSTM, University of Padova, F. Marzolo 9, 35131, Padova, Italy
| | - Luca Dell'Amico
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Serena Berardi
- Department of Chemical and Pharmaceutical Sciences, Centro Interuniversitario per la Conversione Chimica dell'Energia Solare (SolarChem), Sez. di Ferrara, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy
| | - Elisabetta Collini
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Stefano Caramori
- Department of Chemical and Pharmaceutical Sciences, Centro Interuniversitario per la Conversione Chimica dell'Energia Solare (SolarChem), Sez. di Ferrara, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy
| | - Stefano Agnoli
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Andrea Sartorel
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
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13
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Thermodynamic and Kinetic Studies of the Activities of Aldehydic C−H Bonds toward Their H‐Atom Transfer Reactions. ChemistrySelect 2023. [DOI: 10.1002/slct.202204789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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14
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Hintz H, Bower J, Tang J, LaLama M, Sevov C, Zhang S. Copper-Catalyzed Electrochemical C-H Fluorination. CHEM CATALYSIS 2023; 3:100491. [PMID: 36743279 PMCID: PMC9894310 DOI: 10.1016/j.checat.2022.100491] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We report the systematic development of an electrooxidative methodology that translates stoichiometric C-H fluorination reactivity of an isolable CuIII fluoride complex into a catalytic process. The critical challenges of electrocatalysis with a highly reactive CuIII species were addressed by the judicious selection of electrolyte, F- source, and sacrificial electron acceptor. Catalyst-controlled C-H fluorination occurs with a preference for hydridic C-H bonds with high bond dissociation energies over weaker but less hydridic C-H bonds. The selectivity is driven by an oxidative asynchronous proton-coupled elelctron transfer (PCET) at an electrophilic CuIII-F complex. We further demonstrate that the asynchronicity factor of hydrogen atom transfer η can be used as a guideline to rationalize the selectivity of C-H fluorination.
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Affiliation(s)
- Heather Hintz
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Jamey Bower
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Jinghua Tang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Matthew LaLama
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Christo Sevov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
| | - Shiyu Zhang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, United States
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15
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Fu YH, Zhang Y, Wang F, Zhao L, Shen GB, Zhu XQ. Quantitative evaluation of the actual hydrogen atom donating activities of O-H bonds in phenols: structure-activity relationship. RSC Adv 2023; 13:3295-3305. [PMID: 36756400 PMCID: PMC9869660 DOI: 10.1039/d2ra06877j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/31/2022] [Indexed: 01/25/2023] Open
Abstract
The H-donating activity of phenol and the H-abstraction activity of phenol radicals have been extensively studied. In this article, the second-order rate constants of 25 hydrogen atom transfer (HAT) reactions between phenols and PINO and DPPH radicals in acetonitrile at 298 K were studied. Thermo-kinetic parameters ΔG ≠o(XH) were obtained using a kinetic equation [ΔG ≠ XH/Y = ΔG ≠o(XH) + ΔG ≠o(Y)]. Bond dissociation free energies ΔG o(XH) were calculated by the iBonD HM method, whose details are available at https://pka.luoszgroup.com/bde_prediction. Intrinsic resistance energies ΔG ≠ XH/X and ΔG ≠o(X) were determined as ΔG ≠o(XH) and ΔG o(XH) were available. ΔG o(XH), ΔG ≠ XH/X, ΔG ≠o(XH) and ΔG ≠o(X) were used to assess the H-donating abilities of the studied phenols and the H-abstraction abilities of phenol radicals in thermodynamics, kinetics and actual HAT reactions. The effect of structures on these four parameters was discussed. The reliabilities of ΔG ≠o(XH) and ΔG ≠o(X) were examined. The difference between the method of determining ΔG ≠ XH/X mentioned in this study and the dynamic nuclear magnetic method mentioned in the literature was studied. Via this study, not only ΔG o(XH), ΔG ≠ XH/X, ΔG ≠o(XH) and ΔG ≠o(X) of phenols could be quantitatively evaluated, but also the structure-activity relationship of phenols is clearly demonstrated. Moreover, it lays the foundation for designing and synthesizing more antioxidants and radicals.
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Affiliation(s)
- Yan-Hua Fu
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology Anyang Henan 455000 China
| | - Yanwei Zhang
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology Anyang Henan 455000 China
| | - Fang Wang
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology Anyang Henan 455000 China
| | - Ling Zhao
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology Anyang Henan 455000 China
| | - Guang-Bin Shen
- School of Medical Engineering, Jining Medical UniversityJiningShandong272000P. R. China
| | - Xiao-Qing Zhu
- Department of Chemistry, Nankai UniversityTianjin300071China
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16
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An Q, Xing YY, Pu R, Jia M, Chen Y, Hu A, Zhang SQ, Yu N, Du J, Zhang Y, Chen J, Liu W, Hong X, Zuo Z. Identification of Alkoxy Radicals as Hydrogen Atom Transfer Agents in Ce-Catalyzed C-H Functionalization. J Am Chem Soc 2023; 145:359-376. [PMID: 36538367 DOI: 10.1021/jacs.2c10126] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The intermediacy of alkoxy radicals in cerium-catalyzed C-H functionalization via H-atom abstraction has been unambiguously confirmed. Catalytically relevant Ce(IV)-alkoxide complexes have been synthesized and characterized by X-ray diffraction. Operando electron paramagnetic resonance and transient absorption spectroscopy experiments on isolated pentachloro Ce(IV) alkoxides identified alkoxy radicals as the sole heteroatom-centered radical species generated via ligand-to-metal charge transfer (LMCT) excitation. Alkoxy-radical-mediated hydrogen atom transfer (HAT) has been verified via kinetic analysis, density functional theory (DFT) calculations, and reactions under strictly chloride-free conditions. These experimental findings unambiguously establish the critical role of alkoxy radicals in Ce-LMCT catalysis and definitively preclude the involvement of chlorine radical. This study has also reinforced the necessity of a high relative ratio of alcohol vs Ce for the selective alkoxy-radical-mediated HAT, as seemingly trivial changes in the relative ratio of alcohol vs Ce can lead to drastically different mechanistic pathways. Importantly, the previously proposed chlorine radical-alcohol complex, postulated to explain alkoxy-radical-enabled selectivities in this system, has been examined under scrutiny and ruled out by regioselectivity studies, transient absorption experiments, and high-level calculations. Moreover, the peculiar selectivity of alkoxy radical generation in the LMCT homolysis of Ce(IV) heteroleptic complexes has been analyzed and back-electron transfer (BET) may have regulated the efficiency and selectivity for the formation of ligand-centered radicals.
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Affiliation(s)
- Qing An
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.,State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yang-Yang Xing
- Center of Chemistry for Frontier Technologies, Department of Chemistry, State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310007, China.,Beijing National Laboratory for Molecular Sciences, Zhongguancun North First Street NO. 2, Beijing 100190, China.,Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, Zhejiang, China
| | - Ruihua Pu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Menghui Jia
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Yuegang Chen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Anhua Hu
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
| | - Shuo-Qing Zhang
- Center of Chemistry for Frontier Technologies, Department of Chemistry, State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310007, China.,Beijing National Laboratory for Molecular Sciences, Zhongguancun North First Street NO. 2, Beijing 100190, China.,Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, Zhejiang, China
| | - Na Yu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jianbo Du
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.,State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yanxia Zhang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jinquan Chen
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Weimin Liu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xin Hong
- Center of Chemistry for Frontier Technologies, Department of Chemistry, State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310007, China.,Beijing National Laboratory for Molecular Sciences, Zhongguancun North First Street NO. 2, Beijing 100190, China.,Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, Zhejiang, China
| | - Zhiwei Zuo
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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17
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Agarwal RG, Mayer JM. Coverage-Dependent Rate-Driving Force Relationships: Hydrogen Transfer from Cerium Oxide Nanoparticle Colloids. J Am Chem Soc 2022; 144:20699-20709. [DOI: 10.1021/jacs.2c07988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Rishi G. Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut06520-8107, United States
| | - James M. Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut06520-8107, United States
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18
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Ma S, Wang S, Cao J, Liu F. Rapid and Accurate Estimation of Activation Free Energy in Hydrogen Atom Transfer-Based C-H Activation Reactions: From Empirical Model to Artificial Neural Networks. ACS OMEGA 2022; 7:34858-34867. [PMID: 36211072 PMCID: PMC9535641 DOI: 10.1021/acsomega.2c03252] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/07/2022] [Indexed: 06/16/2023]
Abstract
A well-performing machine learning (ML) model is obtained by using proper descriptors and artificial neural network (ANN) algorithms, which can quickly and accurately predict activation free energy in hydrogen atom transfer (HAT)-based sp3 C-H activation. Density functional theory calculations (UωB97X-D) are used to establish the reaction system data sets of methoxyl (CH3O·), trifluoroethoxyl (CF3CH2O·), tert-butoxyl (tBuO·), and cumyloxyl (CumO·) radicals. The simplified Roberts' equation proposed in our recent study works here [R 2 = 0.84, mean absolute error (MAE) = 0.85 kcal/mol]. Its performance is comparable with univariate Mulliken-type electronegativity (χ) with the ANN model. The ANN model with bond dissociation free energy, χ, α-unsaturation, and Nolan buried volume (%V buried) successively improves R 2 and MAE to 0.93 and 0.54 kcal/mol, respectively. It reproduces the test sets of trichloroethoxyl (CCl3CH2O·) with R 2 = 0.87 and MAE = 0.89 kcal/mol and accurately predicts the relative experimental barrier of the HAT reactions with CumO· and the site selectivity of CH3O·.
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Affiliation(s)
- Siqi Ma
- School
of Chemistry and Chemical Engineering, Shanghai
University of Engineering Science, Shanghai 201620, China
| | - Shipeng Wang
- School
of Chemistry and Chemical Engineering, Shanghai
University of Engineering Science, Shanghai 201620, China
| | - Jiawei Cao
- School
of Chemistry and Chemical Engineering, Shanghai
University of Engineering Science, Shanghai 201620, China
| | - Fengjiao Liu
- School
of Chemistry and Chemical Engineering, Shanghai
University of Engineering Science, Shanghai 201620, China
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, California 90095, United States
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19
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Fu Y, Wang Z, Zhang Y, Shen G, Zhu X. Quantitative Evaluation of the Hydrogen‐Donating Abilities ofAmines and Amides in Acetonitrile. ChemistrySelect 2022. [DOI: 10.1002/slct.202202625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Yan‐Hua Fu
- College of Chemistry and Environmental Engineering Anyang Institute of Technology Anyang Henan 455000 China
| | - Zhen Wang
- College of Chemistry and Environmental Engineering Anyang Institute of Technology Anyang Henan 455000 China
| | - Yanwei Zhang
- College of Chemistry and Environmental Engineering Anyang Institute of Technology Anyang Henan 455000 China
| | - Guang‐Bin Shen
- School of Medical Engineering Jining Medical University Jining Shandong 272000 P. R. China
| | - Xiao‐Qing Zhu
- Department of Chemistry Nankai University Tianjin 300071 China
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20
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Paradzinsky M, Ponukumati A, Tanko J. Mechanism and Kinetics of the Reaction of Nitrate Radical with Carboxylic Acids. Chempluschem 2022; 87:e202200213. [DOI: 10.1002/cplu.202200213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/03/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Mark Paradzinsky
- Virginia Tech: Virginia Polytechnic Institute and State University Chemistry UNITED STATES
| | - Aditya Ponukumati
- Virginia Tech: Virginia Polytechnic Institute and State University Chemistry UNITED STATES
| | - James Tanko
- Virginia Polytechnic Institute and State University Chemistry 1040 Drillfield Drive 24060 Blacksburg UNITED STATES
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21
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Nakao H, Mitsunuma H, Kanai M. Site-Selective α-Alkylation of 1,3-Butanediol Using a Thiophosphoric Acid Hydrogen Atom Transfer Catalyst. Chem Pharm Bull (Tokyo) 2022; 70:540-543. [DOI: 10.1248/cpb.c22-00299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hiroyasu Nakao
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
| | | | - Motomu Kanai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
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22
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Galeotti M, Trasatti C, Sisti S, Salamone M, Bietti M. Factors Governing Reactivity and Selectivity in Hydrogen Atom Transfer from C(sp 3)-H Bonds of Nitrogen-Containing Heterocycles to the Cumyloxyl Radical. J Org Chem 2022; 87:7456-7463. [PMID: 35609878 PMCID: PMC9171822 DOI: 10.1021/acs.joc.2c00955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
![]()
A kinetic study of
the hydrogen atom transfer (HAT) reactions from
nitrogen-containing heterocycles (secondary and tertiary lactams,
2-imidazolidinones, 2-oxazolidinones, and succinimides) to the cumyloxyl
radical has been carried out employing laser flash photolysis with
ns time resolution. HAT occurs from the C–H bonds that are
α to nitrogen, activated by hyperconjugative overlap with the
N–C=O π system. In the lactam series, the second-order
HAT rate constant (kH) was observed to
decrease by a factor of ∼4 going from the five- and six-membered
ring derivatives to the eight-membered ones, a behavior that was rationalized
on the basis of a reduced extent of hyperconjugative activation associated
to the greater flexibility of the larger rings compared to the smaller
ones. In the five-membered-ring substrate series, the kH values were observed to increase by >3 orders of
magnitude
on going from succinimide to 2-imidazolidinones, a behavior that was
explained in terms of the divergent contribution of hyperconjugative
activation and deactivating electronic effects determined by ring
functionalities. The results are discussed in the framework of the
development of HAT-based C–H bond functionalization procedures.
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Affiliation(s)
- Marco Galeotti
- Dipartimento di Scienze e Tecnologie Chimiche, Università"Tor Vergata", Via Della Ricerca Scientifica, 1, Rome I-00133, Italy
| | - Chiara Trasatti
- Dipartimento di Scienze e Tecnologie Chimiche, Università"Tor Vergata", Via Della Ricerca Scientifica, 1, Rome I-00133, Italy
| | - Sergio Sisti
- Dipartimento di Scienze e Tecnologie Chimiche, Università"Tor Vergata", Via Della Ricerca Scientifica, 1, Rome I-00133, Italy
| | - Michela Salamone
- Dipartimento di Scienze e Tecnologie Chimiche, Università"Tor Vergata", Via Della Ricerca Scientifica, 1, Rome I-00133, Italy
| | - Massimo Bietti
- Dipartimento di Scienze e Tecnologie Chimiche, Università"Tor Vergata", Via Della Ricerca Scientifica, 1, Rome I-00133, Italy
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23
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Bonciolini S, Noël T, Capaldo L. Synthetic Applications of Photocatalyzed Halogen‐radical mediated Hydrogen Atom Transfer for C−H Bond Functionalization. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200417] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Stefano Bonciolini
- University of Amsterdam: Universiteit van Amsterdam Van 't Hoff Institute for Molecular Sciences NETHERLANDS
| | - Timothy Noël
- University of Amsterdam: Universiteit van Amsterdam Van 't Hoff Institute for Molecular Sciences NETHERLANDS
| | - Luca Capaldo
- University of Amsterdam: Universiteit van Amsterdam Van 't Hoff Institute for Molecular Sciences Science Park 904 1098 XH Amsterdam NETHERLANDS
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24
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Zhao H, Caldora HP, Turner O, Douglas JJ, Leonori D. A Desaturative Approach for Aromatic Aldehyde Synthesis via Synergistic Enamine, Photoredox and Cobalt Triple Catalysis. Angew Chem Int Ed Engl 2022; 61:e202201870. [PMID: 35196413 PMCID: PMC9311220 DOI: 10.1002/anie.202201870] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Indexed: 11/05/2022]
Abstract
Aromatic aldehydes are fundamental intermediates that are widely utilised for the synthesis of important materials across the broad spectrum of chemical industries. Accessing highly substituted derivatives can often be difficult as their functionalizations are generally performed via electrophilic aromatic substitution, SEAr. Here we provide an alternative and mechanistically distinct approach whereby aromatic aldehydes are assembled from saturated precursors via a desaturative process. This novel strategy harnesses the high‐fidelity of Diels–Alder cycloadditions to quickly construct multi‐substituted cyclohexenecarbaldehyde cores which undergo desaturation via the synergistic interplay of enamine, photoredox and cobalt triple catalysis.
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Affiliation(s)
- Huaibo Zhao
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Henry P Caldora
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Oliver Turner
- Oncology R&DI Medicinal Chemistry, AstraZeneca, Darwin Building, Unit 310, Cambridge Science Park, Milton Road, Cambridge, CB4 0WG, UK
| | - James J Douglas
- Early Chemical Development, Pharmaceutical Sciences R&D, AstraZeneca, Macclesfield, UK
| | - Daniele Leonori
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
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25
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Yang B, Lu S, Wang Y, Zhu S. Diverse synthesis of C2-linked functionalized molecules via molecular glue strategy with acetylene. Nat Commun 2022; 13:1858. [PMID: 35388000 PMCID: PMC8986794 DOI: 10.1038/s41467-022-29556-2] [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: 09/15/2021] [Accepted: 03/13/2022] [Indexed: 02/08/2023] Open
Abstract
As the simplest alkyne and an abundant chemical feedstock, acetylene is an ideal two-carbon building block. However, in contrast to substituted alkynes, catalytic methods to incorporate acetylene into fine chemicals are quite limited. Herein, we developed a photoredox-catalyzed synthetic protocol for diverse C2-linked molecules via a molecular glue strategy using gaseous acetylene under mild conditions. Initiated by addition of an acyl radical to acetylene, two cascade transformations follow. One involves a double addition for the formation of 1,4-diketones and the other where the intermediate vinyl ketone is intercepted by a radical formed from a heterocycle. In addition to making two new C-C bonds, two C-H bonds are also created in two mechanistically distinct ways: one via a C-H abstraction and the other via protonation. This system offers a reliable and safe way to incorporate gaseous acetylene into fine chemicals and expands the utility of acetylene in organic synthesis. Although acetylene is an ideal two-carbon building block, very few catalytic methods can be applied to incorporate acetylene into fine chemicals. Here, the authors show photoredox-catalyzed syntheses of C2- linked molecules with gaseous acetylene under mild conditions.
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Affiliation(s)
- Bo Yang
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Shaodong Lu
- Singfar Laboratories, Guangzhou, 510670, China
| | | | - Shifa Zhu
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China.
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26
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Liu F, Ma S, Lu Z, Nangia A, Duan M, Yu Y, Xu G, Mei Y, Bietti M, Houk KN. Hydrogen Abstraction by Alkoxyl Radicals: Computational Studies of Thermodynamic and Polarity Effects on Reactivities and Selectivities. J Am Chem Soc 2022; 144:6802-6812. [PMID: 35378978 DOI: 10.1021/jacs.2c00389] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Density functional theory calculations (ωB97X-D) are reported for the reactions of methoxy, tert-butoxy, trichloroethoxy, and trifluoroethoxy radicals with a series of 26 C-H bonds in different environments characteristic of a variety of hydrocarbons and substituted derivatives. The variations in activation barriers are analyzed with modified Evans-Polanyi treatments to account for polarity and unsaturation effects. The treatments by Roberts and Steel and by Mayer have inspired the development of a simple treatment involving the thermodynamics of reactions, the difference between the reactant radical and product radical electronegativities, and the absence or presence of α-unsaturation. The three-parameter equation (ΔH⧧ = 0.52ΔHrxn(1 - d) - 0.35ΔχAB2 + 10.0, where d = 0.44 when there is α-unsaturation to the reacting C-H bond), correlates well with quantum mechanically computed barriers and shows the quantitative importance of the thermodynamics of reactions (dictated by the reactant and the product bond dissociation energies) and polar effects.
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Affiliation(s)
- Fengjiao Liu
- School of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.,Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Siqi Ma
- School of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Zeying Lu
- School of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Anjanay Nangia
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Meng Duan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Yanmin Yu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.,Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Chemical Engineering, Beijing University of Technology, Beijing 100124, China
| | - Guochao Xu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Ye Mei
- State Key Laboratory of Precision Spectroscopy, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China
| | - Massimo Bietti
- Dipartimento di Scienze e Tecnologie Chimiche, Università ″Tor Vergata″, Via della Ricerca Scientifica, 1 Rome I-00133, Italy
| | - K N Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
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27
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Zhao H, Caldora HP, Turner O, Douglas JJ, Leonori D. A Desaturative Approach for Aromatic Aldehyde Synthesis via Synergistic Enamine, Photoredox and Cobalt Triple Catalysis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202201870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Huaibo Zhao
- Department of Chemistry University of Manchester Oxford Road Manchester M13 9PL UK
| | - Henry P. Caldora
- Department of Chemistry University of Manchester Oxford Road Manchester M13 9PL UK
| | - Oliver Turner
- Oncology R&DI Medicinal Chemistry, AstraZeneca Darwin Building, Unit 310, Cambridge Science Park, Milton Road Cambridge CB4 0WG UK
| | - James J. Douglas
- Early Chemical Development, Pharmaceutical Sciences R&D AstraZeneca Macclesfield UK
| | - Daniele Leonori
- Department of Chemistry University of Manchester Oxford Road Manchester M13 9PL UK
- Institute of Organic Chemistry RWTH Aachen University Landoltweg 1 52056 Aachen Germany
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28
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Galeotti M, Salamone M, Bietti M. Electronic control over site-selectivity in hydrogen atom transfer (HAT) based C(sp 3)-H functionalization promoted by electrophilic reagents. Chem Soc Rev 2022; 51:2171-2223. [PMID: 35229835 DOI: 10.1039/d1cs00556a] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The direct functionalization of C(sp3)-H bonds represents one of the most investigated approaches to develop new synthetic methodology. Among the available strategies for intermolecular C-H bond functionalization, increasing attention has been devoted to hydrogen atom transfer (HAT) based procedures promoted by radical or radical-like reagents, that offer the opportunity to introduce a large variety of atoms and groups in place of hydrogen under mild conditions. Because of the large number of aliphatic C-H bonds displayed by organic molecules, in these processes control over site-selectivity represents a crucial issue, and the associated factors have been discussed. In this review article, attention will be devoted to the role of electronic effects on C(sp3)-H bond functionalization site-selectivity. Through an analysis of the recent literature, a detailed description of the HAT reagents employed in these processes, the associated mechanistic features and the selectivity patterns observed in the functionalization of substrates of increasing structural complexity will be provided.
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Affiliation(s)
- Marco Galeotti
- Dipartimento di Scienze e Tecnologie Chimiche, Università "Tor Vergata", Via della Ricerca Scientifica, 1 I-00133 Rome, Italy.
| | - Michela Salamone
- Dipartimento di Scienze e Tecnologie Chimiche, Università "Tor Vergata", Via della Ricerca Scientifica, 1 I-00133 Rome, Italy.
| | - Massimo Bietti
- Dipartimento di Scienze e Tecnologie Chimiche, Università "Tor Vergata", Via della Ricerca Scientifica, 1 I-00133 Rome, Italy.
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29
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Fu Y, Zerull EE, Schomaker JM, Liu P. Origins of Catalyst-Controlled Selectivity in Ag-Catalyzed Regiodivergent C-H Amination. J Am Chem Soc 2022; 144:2735-2746. [PMID: 35130697 DOI: 10.1021/jacs.1c12111] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ag-catalyzed nitrene transfer (NT) converts C-H bonds into valuable C-N bonds. These reactions offer a promising strategy for catalyst-controlled regiodivergent functionalization of different types of reactive C-H bonds, as the regioselectivity is tunable by varying the steric and electronic environments around the Ag nitrene, as well as the identity of the nitrene precursors and the tether length. Therefore, a unified understanding of how these individual factors affect the regioselectivity is key to the rational design of highly selective and regiodivergent C-H amination reactions. Herein, we report a computational study of various Ag-catalyzed NT reactions that indicates a concerted H-atom transfer (HAT)/C-N bond formation mechanism. A detailed analysis was carried out on the effects of the C-H bond dissociation enthalpy (BDE), charge transfer, ligand-substrate steric repulsions, and transition state ring strain on the stability of the C-H insertion transition states with different Ag nitrene complexes. The ancillary ligands on the Ag and the nitrene precursor identity both affect transition state geometries to furnish differing sensitivities to the BDE, tether length, and electronic effects of the reactive C-H bonds. Based on our understanding of the dominant factors that control selectivity, we established a rational catalyst and precursor selection approach for regiodivergent amination of diverse C-H bonds. The computationally predicted regiodivergent amination of β- and γ-C-H bonds of aliphatic alcohol derivatives was validated by experimental studies.
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Affiliation(s)
- Yue Fu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Emily E Zerull
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Jennifer M Schomaker
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.,Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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30
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Koronkiewicz B, Sayfutyarova ER, Coste SC, Mercado BQ, Hammes-Schiffer S, Mayer JM. Structural and Thermodynamic Effects on the Kinetics of C-H Oxidation by Multisite Proton-Coupled Electron Transfer in Fluorenyl Benzoates. J Org Chem 2022; 87:2997-3006. [PMID: 35113555 DOI: 10.1021/acs.joc.1c02834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Our recent experimental and theoretical investigations have shown that fluorene C-H bonds can be activated through a mechanism in which the proton and electron are transferred from the C-H bond to a separate base and oxidant in a concerted, elementary step. This multisite proton-coupled electron transfer (MS-PCET) mechanism for C-H bond activation was shown to be facilitated by shorter proton donor-acceptor distances. With the goal of intentionally modulating this donor-acceptor distance, we have now studied C-H MS-PCET in the 3-methyl-substituted fluorenyl benzoate (2-Flr-3-Me-BzO-). This derivative was readily oxidized by ferrocenium oxidants by initial C-H MS-PCET, with rate constants that were 6-21 times larger than those for 2-Flr-BzO- with the same oxidants. Structural comparisons by X-ray crystallography and by computations showed that addition of the 3-methyl group caused the expected steric compression; however, the relevant C···O- proton donor-acceptor distance was longer, due to a twist of the carboxylate group. The structural changes induced by the 3-Me group increased the basicity of the carboxylate, weakened the C-H bond, and reduced the reorganization energy for C-H bond cleavage. Thus, the rate enhancement for 2-Flr-3-Me-BzO- was due to effects on the thermochemistry and kinetic barrier, rather than from compression of the C···O- proton donor-acceptor distance. These results highlight both the challenges of controlling molecules on the 0.1 Å length scale and the variety of parameters that affect PCET rate constants.
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Affiliation(s)
- Brian Koronkiewicz
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
| | - Elvira R Sayfutyarova
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
| | - Brandon Q Mercado
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
| | - James M Mayer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
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31
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Zhang Z, Górski B, Leonori D. Merging Halogen-Atom Transfer (XAT) and Copper Catalysis for the Modular Suzuki–Miyaura-Type Cross-Coupling of Alkyl Iodides and Organoborons. J Am Chem Soc 2022; 144:1986-1992. [PMID: 35061390 PMCID: PMC9098170 DOI: 10.1021/jacs.1c12649] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
![]()
We report here a mechanistically
distinct approach to achieve Suzuki–Miyaura-type
cross-couplings between alkyl iodides and aryl organoborons. This
process requires a copper catalyst but, in contrast with previous
approaches based on palladium and nickel systems, does not utilizes
the metal for the activation of the alkyl electrophile. Instead, this
strategy exploits the halogen-atom-transfer ability of α-aminoalkyl
radicals to convert secondary alkyl iodides into the corresponding
alkyl radicals that then are coupled with aryl, vinyl, alkynyl, benzyl,
and allyl boronate species. These novel coupling reactions feature
a simple setup and conditions (1 h at room temperature) and facilitate
access to privileged motifs targeted by the pharmaceutical sector.
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Affiliation(s)
- Zhenhua Zhang
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Bartosz Górski
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Daniele Leonori
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
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32
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Maloney TP, Dohoda AF, Zhu AC, Michael FE. Stereoretentive and Regioselective Selenium-catalyzed Intermolecular Propargylic C-H Amination of Alkynes. Chem Sci 2022; 13:2121-2127. [PMID: 35308840 PMCID: PMC8849008 DOI: 10.1039/d1sc07067c] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 01/26/2022] [Indexed: 11/21/2022] Open
Abstract
Herein we report an intermolecular propargylic C–H amination of alkynes. This reaction is operationally convenient and requires no transition metal catalysts or additives. Terminal, silyl, and internal alkynes bearing a wide range of functional groups can be aminated in high yields. The regioselectivity of amination for unsymmetrical internal alkynes is strongly influenced by substitution pattern (tertiary > secondary > primary) and by relatively remote heteroatomic substituents. We demonstrate that amination of alkynes bearing α-stereocenters occurs with retention of configuration at the newly-formed C–N bond. Competition experiments between alkynes, kinetic isotope effects, and DFT calculations are performed to confirm the mechanistic hypothesis that initial ene reaction of a selenium bis(imide) species is the rate- and product-determining step. This ene reaction has a transition state that results in substantial partial positive charge development at the carbon atom closer to the amination position. Inductive and/or hyperconjugative stabilization or destabilization of this positive charge explains the observed regioselectivities. Selenium catalysis enables a general intermolecular propargylic C–H amination of alkynes. The concerted mechanism gives rise to high regioselectivity for the more electron-rich end of the alkyne and retention of the C–H propargylic stereocenter.![]()
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Affiliation(s)
- T Parker Maloney
- University of Washington, Department of Chemistry Box 351700 Seattle Washington 98195-1700 USA
| | - Alexander F Dohoda
- University of Washington, Department of Chemistry Box 351700 Seattle Washington 98195-1700 USA
| | - Alec C Zhu
- University of Washington, Department of Chemistry Box 351700 Seattle Washington 98195-1700 USA
| | - Forrest E Michael
- University of Washington, Department of Chemistry Box 351700 Seattle Washington 98195-1700 USA
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33
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Coste SC, Brezny AC, Koronkiewicz B, Mayer JM. C-H oxidation in fluorenyl benzoates does not proceed through a stepwise pathway: revisiting asynchronous proton-coupled electron transfer. Chem Sci 2021; 12:13127-13136. [PMID: 34745543 PMCID: PMC8513817 DOI: 10.1039/d1sc03344a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/09/2021] [Indexed: 11/21/2022] Open
Abstract
2-Fluorenyl benzoates were recently shown to undergo C–H bond oxidation through intramolecular proton transfer coupled with electron transfer to an external oxidant. Kinetic analysis revealed unusual rate-driving force relationships. Our analysis indicated a mechanism of multi-site concerted proton–electron transfer (MS-CPET) for all of these reactions. More recently, an alternative interpretation of the kinetic data was proposed to explain the unusual rate-driving force relationships, invoking a crossover from CPET to a stepwise mechanism with an initial intramolecular proton transfer (PT) (Costentin, Savéant, Chem. Sci., 2020, 11, 1006). Here, we show that this proposed alternative pathway is untenable based on prior and new experimental assessments of the intramolecular PT equilibrium constant and rates. Measurement of the fluorenyl 9-C–H pKa, H/D exchange experiments, and kinetic modelling with COPASI eliminate the possibility of a stepwise mechanism for C–H oxidation in the fluorenyl benzoate series. Implications for asynchronous (imbalanced) MS-CPET mechanisms are discussed with respect to classical Marcus theory and the quantum-mechanical treatment of concerted proton–electron transfer. 2-Fluorenyl benzoates were recently shown to undergo C–H bond oxidation through intramolecular proton transfer coupled with electron transfer to an external oxidant.![]()
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Affiliation(s)
- Scott C Coste
- Department of Chemistry, Yale University New Haven CT 06520-8107 USA
| | - Anna C Brezny
- Department of Chemistry, Skidmore College Saratoga Springs New York 12866 USA
| | | | - James M Mayer
- Department of Chemistry, Yale University New Haven CT 06520-8107 USA
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34
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Chang L, An Q, Duan L, Feng K, Zuo Z. Alkoxy Radicals See the Light: New Paradigms of Photochemical Synthesis. Chem Rev 2021; 122:2429-2486. [PMID: 34613698 DOI: 10.1021/acs.chemrev.1c00256] [Citation(s) in RCA: 130] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Alkoxy radicals are highly reactive species that have long been recognized as versatile intermediates in organic synthesis. However, their development has long been impeded due to a lack of convenient methods for their generation. Thanks to advances in photoredox catalysis, enabling facile access to alkoxy radicals from bench-stable precursors and free alcohols under mild conditions, research interest in this field has been renewed. This review comprehensively summarizes the recent progress in alkoxy radical-mediated transformations under visible light irradiation. Elementary steps for alkoxy radical generation from either radical precursors or free alcohols are central to reaction development; thus, each section is categorized and discussed accordingly. Throughout this review, we have focused on the different mechanisms of alkoxy radical generation as well as their impact on synthetic utilizations. Notably, the catalytic generation of alkoxy radicals from abundant alcohols is still in the early stage, providing intriguing opportunities to exploit alkoxy radicals for diverse synthetic paradigms.
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Affiliation(s)
- Liang Chang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 200032 Shanghai, China.,School of Pharmacy, Nanjing University of Chinese Medicine, 210023 Nanjing, China
| | - Qing An
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Lingfei Duan
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 200032 Shanghai, China
| | - Kaixuan Feng
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 200032 Shanghai, China
| | - Zhiwei Zuo
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 200032 Shanghai, China
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