1
|
Bray JM, Stephens SM, Weierbach SM, Vargas K, Lambert KM. Recent advancements in the use of Bobbitt's salt and 4-acetamidoTEMPO. Chem Commun (Camb) 2023; 59:14063-14092. [PMID: 37946555 DOI: 10.1039/d3cc04709a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Recent advances in synthetic methodologies for selective, oxidative transformations using Bobbitt's salt (4-acetamido-2,2,6,6-tetramethyl-1-oxopiperidinium tetrafluoroborate, 1) and its stable organic nitroxide counterpart ACT (4-acetamidoTEMPO, 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl, 2) have led to increased applications across a broad array of disciplines. Current applications and mechanistic understanding of these metal-free, environmentally benign, and easily accessible organic oxidants now span well-beyond the seminal use of 1 and 2 in selective alcohol oxidations. New synthetic methodologies for the oxidation of alcohols, ethers, amines, thiols, C-H bonds and other functional groups with 1 and 2 along with the field's current mechanistic understandings of these processes are presented alongside our contributions in this area. Exciting new areas harnessing the unique properties of these oxidants include: applications to drug discovery and natural product total synthesis, the development of new electrocatalytic methods for depolymerization of lignin and modification of other biopolymers, in vitro and in vivo nucleoside modifications, applications in supramolecular catalysis, the synthesis of new polymers and materials, enhancements in the design of organic redox flow batteries, uses in organic fuel cells, applications and advancements in energy storage, the development of electrochemical sensors, and the production of renewable fuels.
Collapse
Affiliation(s)
- Jean M Bray
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Ave, Norfolk, VA 23529, USA.
| | - Shannon M Stephens
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Ave, Norfolk, VA 23529, USA.
| | - Shayne M Weierbach
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Ave, Norfolk, VA 23529, USA.
| | - Karen Vargas
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Ave, Norfolk, VA 23529, USA.
| | - Kyle M Lambert
- Department of Chemistry and Biochemistry, Old Dominion University, 4501 Elkhorn Ave, Norfolk, VA 23529, USA.
| |
Collapse
|
2
|
Giraldi V, Giunchino F, Casacchia ME, Cantelli A, Lucarini M, Giacomini D. N-Sulfenylation of β-Lactams: Radical Reaction of N-Bromo-azetidinones by TEMPO Catalysis. J Org Chem 2023; 88:14728-14735. [PMID: 37769169 PMCID: PMC10594653 DOI: 10.1021/acs.joc.3c01759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Indexed: 09/30/2023]
Abstract
Azetidinones with a sulfenyl group on the β-lactam nitrogen atom show interesting biological activities as antimicrobial agents and enzyme inhibitors. We report in the present study a versatile synthesis of N-sulfenylated azetidinones starting from the corresponding N-bromo derivatives by means of the (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) radical as the catalyst and disulfides. Preparation of N-halo-azetidinones was studied and optimized. The reactivity of N-bromo-azetidinone 2a as a model compound in the presence of TEMPO radical was investigated by NMR and electron paramagnetic resonance (EPR) spectroscopy studies. Optimization of the reaction conditions allowed the access of N-alkylthio- or N-arylthio-azetidinones from 55 to 92% yields, and the method exhibited a good substrate scope.
Collapse
Affiliation(s)
- Valentina Giraldi
- Department
of Chemistry a “Giacomo Ciamician”, University of Bologna, Via Piero Gobetti, 87, Bologna 40129, Italy
| | - Francesco Giunchino
- Department
of Chemistry a “Giacomo Ciamician”, University of Bologna, Via Piero Gobetti, 87, Bologna 40129, Italy
| | - Maria Edith Casacchia
- Department
of Chemistry a “Giacomo Ciamician”, University of Bologna, Via Piero Gobetti, 87, Bologna 40129, Italy
- Department
of Physical and Chemical Sciences, University
of Aquila, Via Vetoio, Coppito, L’Aquila 67100, Italy
| | - Andrea Cantelli
- Department
of Chemistry a “Giacomo Ciamician”, University of Bologna, Via Piero Gobetti, 87, Bologna 40129, Italy
| | - Marco Lucarini
- Department
of Chemistry a “Giacomo Ciamician”, University of Bologna, Via Piero Gobetti, 87, Bologna 40129, Italy
| | - Daria Giacomini
- Department
of Chemistry a “Giacomo Ciamician”, University of Bologna, Via Piero Gobetti, 87, Bologna 40129, Italy
| |
Collapse
|
3
|
Wu J, Luo Y, Chen L, Sun X, Chen X, Qin S, Feng W, Li X, Yuan L. A host–guest interaction activated Bobbitt oxidant for highly efficient oxidation of alcohols. Chem Commun (Camb) 2022; 58:12867-12870. [DOI: 10.1039/d2cc05027g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Host–guest complexation using hydrogen-bonded macrocycles was found to enable activation of the Bobbitt oxidant reagent, which greatly facilitates the highly efficient oxidation of unactivated primary alcohols.
Collapse
Affiliation(s)
- Jinyang Wu
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Youran Luo
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Lingxuan Chen
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Xuan Sun
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Xinnan Chen
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Song Qin
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Wen Feng
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Xiaowei Li
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Lihua Yuan
- Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, College of Chemistry, Sichuan University, Chengdu, 610064, China
| |
Collapse
|
4
|
Dergunov SA. Biomimetic controlled radical photopolymerization in a two-dimensional organized environment under visible light. Chem Commun (Camb) 2021; 57:10612-10615. [PMID: 34570148 DOI: 10.1039/d1cc03982b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fast and well-controlled photoinduced atom transfer radical polymerization (photoATRP) in the organized medium of a bilayer activated by visible light under environmentally friendly mild aqueous conditions leads to polymers with predetermined molecular weight and low dispersity. The decisive parameter for photoATRP of monomers in the organized medium was their mobility and orientation with respect to the bilayer and the photoredox catalyst localized in the interstitial layer.
Collapse
Affiliation(s)
- Sergey A Dergunov
- Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, 06269, CT, USA.
| |
Collapse
|
5
|
Rohland P, Schreyer K, Burges R, Fritz N, Hager MD, Schubert US. Liquid Chromatography Analysis of Reactive Oxoammonium Cations. Chromatographia 2021. [DOI: 10.1007/s10337-021-04084-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractThis study presents the first liquid chromatography method for the quantitative and qualitative analysis of highly reactive oxoammonium cations based on a simple derivatization reaction. Rapid 1,2-electrophilic addition reactions with olefins were used to transform these reactive species into analyzable derivates. Three model substances were chosen to represent each of the main application fields of oxoammonium cations and to demonstrate the versatility of the method. The measuring protocol was validated according to the ICH and USP guidelines. The method revealed an excellent linearity (R2 = 0.9980–0.9990) with a low limit of detection (0.16–0.14 mmol L−1) and a low limit of quantification (0.55–0.43 mmol L−1). The protocol was finally used to determine the oxoammonium cations in the presence of their corresponding radical, showing a robustness against impurity concentration of up to approx. 30%.
Collapse
|
6
|
Ponedel'kina IY, Khaybrakhmanova EA, Tyumkina TV. Reinvestigation of 2,2,6,6-tetramethylpiperidine-1-oxoammonium mono- and tribromide: From old compounds to new findings. RESULTS IN CHEMISTRY 2021. [DOI: 10.1016/j.rechem.2021.100214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
7
|
Lee JW, Lim S, Maienshein DN, Liu P, Ngai MY. Redox-Neutral TEMPO Catalysis: Direct Radical (Hetero)Aryl C-H Di- and Trifluoromethoxylation. Angew Chem Int Ed Engl 2020; 59:21475-21480. [PMID: 32830430 PMCID: PMC7720849 DOI: 10.1002/anie.202009490] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/12/2020] [Indexed: 12/15/2022]
Abstract
Applications of TEMPO. catalysis for the development of redox-neutral transformations are rare. Reported here is the first TEMPO. -catalyzed, redox-neutral C-H di- and trifluoromethoxylation of (hetero)arenes. The reaction exhibits a broad substrate scope, has high functional-group tolerance, and can be employed for the late-stage functionalization of complex druglike molecules. Kinetic measurements, isolation and resubjection of catalytic intermediates, UV/Vis studies, and DFT calculations support the proposed oxidative TEMPO. /TEMPO+ redox catalytic cycle. Mechanistic studies also suggest that Li2 CO3 plays an important role in preventing catalyst deactivation. These findings will provide new insights into the design and development of novel reactions through redox-neutral TEMPO. catalysis.
Collapse
Affiliation(s)
- Johnny W Lee
- Department of Chemistry and Institute of Chemical Biology and Drug Discovery, State University of New York, Stony Brook, NY, 11794, USA
| | - Sanghyun Lim
- Department of Chemistry and Institute of Chemical Biology and Drug Discovery, State University of New York, Stony Brook, NY, 11794, USA
| | - Daniel N Maienshein
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Ming-Yu Ngai
- Department of Chemistry and Institute of Chemical Biology and Drug Discovery, State University of New York, Stony Brook, NY, 11794, USA
| |
Collapse
|
8
|
Naveed KUR, Wang L, Yu H, Teng L, Uddin MA, Fahad S, Ullah RS, Nazir A, Elshaarani T. Synthesis of spin labeled ethylene glycol based polymers and study of their segmental motion. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128528] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
9
|
Lee JW, Lim S, Maienshein DN, Liu P, Ngai M. Redox‐Neutral TEMPO Catalysis: Direct Radical (Hetero)Aryl C−H Di‐ and Trifluoromethoxylation. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202009490] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Johnny W. Lee
- Department of Chemistry and Institute of Chemical Biology and Drug Discovery State University of New York Stony Brook NY 11794 USA
| | - Sanghyun Lim
- Department of Chemistry and Institute of Chemical Biology and Drug Discovery State University of New York Stony Brook NY 11794 USA
| | | | - Peng Liu
- Department of Chemistry University of Pittsburgh Pittsburgh PA 15260 USA
| | - Ming‐Yu Ngai
- Department of Chemistry and Institute of Chemical Biology and Drug Discovery State University of New York Stony Brook NY 11794 USA
| |
Collapse
|
10
|
Synthesis of poly(diethylaminoethyl methacrylate-co-2,2,6,6-tetramethyl-4-piperidyl methacrylate)s and their segmental motion study. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04717-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
11
|
Nakamura A, Latif MA, Deck PA, Castagnoli N, Tanko JM. Evidence for a Proton-Coupled Electron Transfer Mechanism in a Biomimetic System for Monoamine Oxidase B Catalysis. Chemistry 2020; 26:823-829. [PMID: 31658386 DOI: 10.1002/chem.201904634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Indexed: 11/11/2022]
Abstract
Mechanistic studies with 5-ethyl-3-methyllumiflavinium (Fl+ ) perchlorate, a biomimetic model for flavoenzyme monoamine oxidase B (MAO-B) catalysis, and the tertiary, allyl amine 1-methyl-4-(1-methyl-1 H-pyrrol-2-yl)-1,2,3,6-tetrahydropyridine (MMTP) reveal that proton-coupled electron transfer (PCET) may be an important pathway for MAO catalysis. The first step involves a single-electron transfer (SET) leading to the free radicals Fl. and MMTP. , the latter produced by deprotonation of the initially formed and highly acidic MMTP.+ . Molecular oxygen (O2 ) is found to play a hitherto unrecognized role in the early steps of the oxidation. MMTP and several structurally similar tertiary amines are the only tertiary amines oxidized by MAO, and their structural/electronic properties provide the key to understanding this behavior. A general hypothesis about the role of SET in MAO catalysis, and the recognition that PCET occurs with appropriately substituted substrates is presented.
Collapse
Affiliation(s)
- Akiko Nakamura
- Department of Chemistry, Virginia Tech, Blacksburg, VA, 24060, USA
| | | | - Paul A Deck
- Department of Chemistry, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Neal Castagnoli
- Department of Chemistry, Virginia Tech, Blacksburg, VA, 24060, USA
| | - James M Tanko
- Department of Chemistry, Virginia Tech, Blacksburg, VA, 24060, USA
| |
Collapse
|
12
|
Naveed KUR, Wang L, Yu H, Summe Ullah R, Nazir A, Fahad S, Elshaarani T, Usman M, Khan A. Synthesis of spin-labelled poly(acrylic acid)s and their segmental motion study. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1685690] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Kaleem-Ur-Rahman Naveed
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| | - Li Wang
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| | - Haojie Yu
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| | - Raja Summe Ullah
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| | - Ahsan Nazir
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| | - Shah Fahad
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| | - Tarig Elshaarani
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| | - Muhammad Usman
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| | - Amin Khan
- State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou, People’s Republic of China
| |
Collapse
|
13
|
Khodeir M, Ernould B, Brassinne J, Ghiassinejad S, Jia H, Antoun S, Friebe C, Schubert US, Kochovski Z, Lu Y, Van Ruymbeke E, Gohy JF. Synthesis and characterisation of redox hydrogels based on stable nitroxide radicals. SOFT MATTER 2019; 15:6418-6426. [PMID: 31338513 DOI: 10.1039/c9sm00905a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The principle of encapsulation/release of a guest molecule from stimuli responsive hydrogels (SRHs) is mainly realised with pH, temperature or light stimuli. However, only a limited number of redox responsive hydrogels have been investigated so far. We report here the development of a SRH that can release its guest molecule upon a redox stimulus. To obtain this redox hydrogel, we have introduced into the hydrogel the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) stable nitroxide radical, which can be reversibly oxidized into an oxoammonium cation (TEMPO+). Water solubility is provided by the presence of the (oligoethyleneglycol)methacrylate (OEGMA) comonomer. Electrochemical and mechanical characterization showed that those gels exhibit interesting physicochemical properties, making them very promising candidates for practical use in a wide range of applications.
Collapse
Affiliation(s)
- Miriam Khodeir
- Institute of Condensed Matter and Nanosciences (IMCN), Bio and Soft Matter (BSMA), Université catholique de Louvain (UCL), Place L. Pasteur 1 & Croix du Sud 1, B-1348 Louvain-la-Neuve, Belgium.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Coman AG, Stavarache C, Paun A, Popescu CC, Hădade ND, Ionita P, Matache M. A novel profluorescent paramagnetic diaza-crown ether: synthesis, characterization and alkaline metal-ion complexation. RSC Adv 2019; 9:6078-6083. [PMID: 35517289 PMCID: PMC9060903 DOI: 10.1039/c8ra09828j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/14/2019] [Indexed: 12/20/2022] Open
Abstract
Starting from Kryptofix 22 two different branches were covalently attached through the nitrogen atoms, one containing a fluorescent moiety and the other the stable free radical TEMPO. The novel derivative exhibits fluorescence and paramagnetic properties, while the diaza-crown part ensures the affinity for alkaline metal-ions. Starting from Kryptofix 22 two different branches were covalently attached through the nitrogen atoms, one containing a fluorescent moiety and the other the stable free radical TEMPO.![]()
Collapse
Affiliation(s)
- Anca G Coman
- University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, Research Centre of Applied Organic Chemistry 90-92 Panduri Street RO-050663 Bucharest Romania
| | - Cristina Stavarache
- Institute of Organic Chemistry "C.D. Nenitescu" of the Romanian Academy 202B Spl. Independentei 060023 Bucharest Romania
| | - Anca Paun
- University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, Research Centre of Applied Organic Chemistry 90-92 Panduri Street RO-050663 Bucharest Romania
| | - Codruţa C Popescu
- University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, Research Centre of Applied Organic Chemistry 90-92 Panduri Street RO-050663 Bucharest Romania
| | - Niculina D Hădade
- Faculty of Chemistry and Chemical Engineering, Supramolecular Organic and Organometallic Chemistry Centre, "Babes-Bolyai" University 11 Arany Janos Str. RO-400028-Cluj-Napoca Romania
| | - Petre Ionita
- University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, Research Centre of Applied Organic Chemistry 90-92 Panduri Street RO-050663 Bucharest Romania .,Institute of Physical Chemistry "Ilie Murgulescu" 202 Splaiul Independentei Bucharest Romania
| | - Mihaela Matache
- University of Bucharest, Faculty of Chemistry, Department of Organic Chemistry, Biochemistry and Catalysis, Research Centre of Applied Organic Chemistry 90-92 Panduri Street RO-050663 Bucharest Romania
| |
Collapse
|
15
|
Stoyanovsky AD, Stoyanovsky DA. 1-Oxo-2,2,6,6-tetramethylpiperidinium bromide converts α-H N,N-dialkylhydroxylamines to nitrones via a two-electron oxidation mechanism. Sci Rep 2018; 8:15323. [PMID: 30333514 PMCID: PMC6193029 DOI: 10.1038/s41598-018-33639-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 10/02/2018] [Indexed: 01/13/2023] Open
Abstract
Herein we provide experimental proof that 1-oxo-2,2,6,6-tetramethylpiperidinium bromide converts α-H N,N-dialkylhydroxylamines to nitrones via a two-electron oxidation mechanism. The reactions reported are rapid, proceed under mild conditions, and afford nitrones in excellent yields.
Collapse
Affiliation(s)
| | - Detcho A Stoyanovsky
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
| |
Collapse
|
16
|
Gerken JB, Pang YQ, Lauber MB, Stahl SS. Structural Effects on the pH-Dependent Redox Properties of Organic Nitroxyls: Pourbaix Diagrams for TEMPO, ABNO, and Three TEMPO Analogs. J Org Chem 2017; 83:7323-7330. [PMID: 29182282 DOI: 10.1021/acs.joc.7b02547] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Electrochemical studies of the reduction and oxidation reactions of five different organic nitroxyls have been performed across a wide pH range (0-13). The resulting Pourbaix diagrams illustrate structural effects on their various redox potentials and on the p Ka values of the corresponding hydroxylamine and hydroxylammonium ions. Evidence is also given for the reversible formation of a hydroxylamine N-oxide when nitroxyls are oxidized in alkaline media. Structural effects on the thermodynamics of this reaction are assessed.
Collapse
Affiliation(s)
- James B Gerken
- Department of Chemistry , University of Wisconsin - Madison , 1101 University Avenue , Madison , Wisconsin 53706-1322 , United States
| | - Yutong Q Pang
- Department of Chemistry , University of Wisconsin - Madison , 1101 University Avenue , Madison , Wisconsin 53706-1322 , United States
| | - Markus B Lauber
- Department of Chemistry , University of Wisconsin - Madison , 1101 University Avenue , Madison , Wisconsin 53706-1322 , United States
| | - Shannon S Stahl
- Department of Chemistry , University of Wisconsin - Madison , 1101 University Avenue , Madison , Wisconsin 53706-1322 , United States
| |
Collapse
|