1
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LaPorte AJ, Feldner JE, Spies JC, Maher TJ, Burke MD. MIDA- and TIDA-Boronates Stabilize α-Radicals Through B-N Hyperconjugation. Angew Chem Int Ed Engl 2023; 62:e202309566. [PMID: 37540542 DOI: 10.1002/anie.202309566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 08/05/2023]
Abstract
Multifunctional organoboron compounds increasingly enable the simple generation of complex, Csp3 -rich small molecules. The ability of boron-containing functional groups to modify the reactivity of α-radicals has also enabled a myriad of chemical reactions. Boronic esters with vacant p-orbitals have a significant stabilizing effect on α-radicals due to delocalization of spin density into the empty orbital. The effect of coordinatively saturated derivatives, such as N-methyliminodiacetic acid (MIDA) boronates and counterparts, remains less clear. Herein, we demonstrate that coordinatively saturated MIDA and TIDA boronates stabilize secondary alkyl α-radicals via σB-N hyperconjugation in a manner that allows site-selective C-H bromination. DFT calculated radical stabilization energies and spin density maps as well as LED NMR kinetic analysis of photochemical bromination rates of different boronic esters further these findings. This work clarifies that the α-radical stabilizing effect of boronic esters does not only proceed via delocalization of radical character into vacant boron p-orbitals, but that hyperconjugation of tetrahedral boron-containing functional groups and their ligand electron delocalizing ability also play a critical role. These findings establish boron ligands as a useful dial for tuning reactivity at the α-carbon.
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Affiliation(s)
- Antonio J LaPorte
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
| | - Jack E Feldner
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
| | - Jan C Spies
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
| | - Tom J Maher
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
| | - Martin D Burke
- Department of Chemistry, University of Illinois, Urbana, IL, 61820, USA
- Carle Illinois College of Medicine, University of Illinois, Urbana, IL, 61820, USA
- Department of Biochemistry, University of Illinois, Urbana, IL, 61820, USA
- Arnold and Mable Beckman Institute, University of Illinois, Urbana, IL, 61820, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, 61820, USA
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2
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Li M, He Z, Zhao W, Yu Y, Huang F, Baell JB. Photocatalytic Benzylic C-H Oxidation/Cyclization of Enaminones to the Synthesis of Polysubstituted Oxazoles. J Org Chem 2023. [PMID: 37262016 DOI: 10.1021/acs.joc.3c00269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Photocatalytic benzylic C-H oxidation/cyclization of enaminones was efficiently achieved to afford oxazole derivatives under mild conditions. The oxygen in the oxazole ring originated from green oxidant molecular oxygen. The synthetic protocol features broad substrate scopes and good functional group tolerance. The combined experimental and theoretical studies reveal that in suit benzylic C-H oxidation/cyclization is involved in the reaction transformations.
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Affiliation(s)
- Mingrui Li
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing 211816, P. R. China
| | - Zhiqin He
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Wei Zhao
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Yang Yu
- School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, P. R. China
| | - Fei Huang
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing 211816, P. R. China
| | - Jonathan B Baell
- School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing 211816, P. R. China
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3
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Li J, Siang Tan S, Kyne SH, Wai Hong Chan P. Minisci‐Type Alkylation of
N
‐Heteroarenes by
N
‐(Acyloxy)phthalimide Esters Mediated by a Hantzsch Ester and Blue LED Light. Adv Synth Catal 2022. [DOI: 10.1002/adsc.202101195] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jiacheng Li
- School of Chemistry Monash University Clayton Victoria 3800 Australia
| | - Suan Siang Tan
- School of Chemistry Monash University Clayton Victoria 3800 Australia
| | - Sara Helen Kyne
- School of Chemistry Monash University Clayton Victoria 3800 Australia
| | - Philip Wai Hong Chan
- Department of Biological Environment Jiyang College of Zhejiang A&F University Hang Zhou Shi, Zhuji 311800, People's Republic of China
- School of Chemistry Monash University Clayton Victoria 3800 Australia
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4
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Sowndarya S V S, St John PC, Paton RS. A quantitative metric for organic radical stability and persistence using thermodynamic and kinetic features. Chem Sci 2021; 12:13158-13166. [PMID: 34745547 PMCID: PMC8514092 DOI: 10.1039/d1sc02770k] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/03/2021] [Indexed: 01/04/2023] Open
Abstract
Long-lived organic radicals are promising candidates for the development of high-performance energy solutions such as organic redox batteries, transistors, and light-emitting diodes. However, “stable” organic radicals that remain unreactive for an extended time and that can be stored and handled under ambient conditions are rare. A necessary but not sufficient condition for organic radical stability is the presence of thermodynamic stabilization, such as conjugation with an adjacent π-bond or lone-pair, or hyperconjugation with a σ-bond. However, thermodynamic factors alone do not result in radicals with extended lifetimes: many resonance-stabilized radicals are transient species that exist for less than a millisecond. Kinetic stabilization is also necessary for persistence, such as steric effects that inhibit radical dimerization or reaction with solvent molecules. We describe a quantitative approach to map organic radical stability, using molecular descriptors intended to capture thermodynamic and kinetic considerations. The comparison of an extensive dataset of quantum chemical calculations of organic radicals with experimentally-known stable radical species reveals a region of this feature space where long-lived radicals are located. These descriptors, based upon maximum spin density and buried volume, are combined into a single metric, the radical stability score, that outperforms thermodynamic scales based on bond dissociation enthalpies in identifying remarkably long-lived radicals. This provides an objective and accessible metric for use in future molecular design and optimization campaigns. We demonstrate this approach in identifying Pareto-optimal candidates for stable organic radicals. Molecular descriptors encoding kinetic and thermodynamic stabilization capture the difference between transient and persistent organic radicals.![]()
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Affiliation(s)
- Shree Sowndarya S V
- Department of Chemistry, Colorado State University Fort Collins CO 80523 USA
| | - Peter C St John
- Biosciences Center, National Renewable Energy Laboratory Golden CO 80401 USA
| | - Robert S Paton
- Department of Chemistry, Colorado State University Fort Collins CO 80523 USA
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5
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Wagner JP. Criegee Intermediates in Autoxidation Reactions: Mechanistic Considerations. J Phys Chem A 2021; 125:406-410. [PMID: 33393293 DOI: 10.1021/acs.jpca.0c09971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Products of Criegee intermediate (CI) chemistry were recently detected in radical chain autoxidation reactions involving β-hydroxyperoxy radicals. Here, we demonstrate by means of accurate G4 computations that direct scission of the latter to CIs and radical byproducts is thermodynamically highly unfavorable. Instead, the reaction becomes possible through a hydrogen abstraction reaction that could proceed by reversible formation of a dimeric tetroxide and a subsequent [1,6] hydrogen shift of the hydroxy hydrogen.
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Affiliation(s)
- J Philipp Wagner
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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6
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Wang X, Liu RF, Cork J, Gu Y, Upham DC, Laycock B, McFarland EW. Investigation of the Bromination/Dehydrobromination of Long Chain Alkanes. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.7b01039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiaoyu Wang
- Dow
Centre for Sustainable Engineering Innovation, School of Chemical
Engineering, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Ru-Fen Liu
- Departments
of Chemical Engineering and Chemistry, The University of California, Santa
Barbara, California 93106, United States
| | - Jorja Cork
- Dow
Centre for Sustainable Engineering Innovation, School of Chemical
Engineering, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Yi Gu
- Dow
Centre for Sustainable Engineering Innovation, School of Chemical
Engineering, The University of Queensland, St Lucia, QLD 4072, Australia
| | - David C. Upham
- Departments
of Chemical Engineering and Chemistry, The University of California, Santa
Barbara, California 93106, United States
| | - Bronwyn Laycock
- Dow
Centre for Sustainable Engineering Innovation, School of Chemical
Engineering, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Eric W. McFarland
- Dow
Centre for Sustainable Engineering Innovation, School of Chemical
Engineering, The University of Queensland, St Lucia, QLD 4072, Australia
- Departments
of Chemical Engineering and Chemistry, The University of California, Santa
Barbara, California 93106, United States
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7
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Van Hoomissen DJ, Vyas S. Impact of Conjugation and Hyperconjugation on the Radical Stability of Allylic and Benzylic Systems: A Theoretical Study. J Org Chem 2017; 82:5731-5742. [DOI: 10.1021/acs.joc.7b00549] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Shubham Vyas
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
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8
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Trinquier G, Malrieu JP. Spreading out spin density in polyphenalenyl radicals. Phys Chem Chem Phys 2017; 19:27623-27642. [DOI: 10.1039/c7cp04930g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Properly-designed monoradicals built from polycondensed phenalene units can enforce flattening of spin distributions.
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Affiliation(s)
- Georges Trinquier
- Laboratoire de Chimie et Physique Quantiques (CNRS-UMR5626)
- IRSAMC
- Université Paul-Sabatier (Toulouse III)
- 31062 Toulouse Cedex
- France
| | - Jean-Paul Malrieu
- Laboratoire de Chimie et Physique Quantiques (CNRS-UMR5626)
- IRSAMC
- Université Paul-Sabatier (Toulouse III)
- 31062 Toulouse Cedex
- France
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9
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Li L, Fan HJ, Hu HQ. Assessment of Contemporary Theoretical Methods for Bond Dissociation Enthalpies. CHINESE J CHEM PHYS 2016. [DOI: 10.1063/1674-0068/29/cjcp1512266] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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10
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Guan XH, Wang D, Wang Q, Chi MS, Liu CG. Estimation of various chemical bond dissociation enthalpies of large-sized kerogen molecules using DFT methods. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1143983] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Xiao-Hui Guan
- College of Chemical Engineering, Northeast Dianli University, Jilin, Jilin Province, P. R. China
| | - Di Wang
- College of Chemical Engineering, Northeast Dianli University, Jilin, Jilin Province, P. R. China
| | - Qing Wang
- College of Chemical Engineering, Northeast Dianli University, Jilin, Jilin Province, P. R. China
| | - Ming-Shu Chi
- College of Chemical Engineering, Northeast Dianli University, Jilin, Jilin Province, P. R. China
| | - Chun-Guang Liu
- College of Chemical Engineering, Northeast Dianli University, Jilin, Jilin Province, P. R. China
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11
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Soydaş E, Bozkaya U. Assessment of the orbital-optimized coupled-electron pair theory for thermochemistry and kinetics: Improving on CCSD and CEPA(1). J Comput Chem 2014; 35:1073-81. [DOI: 10.1002/jcc.23592] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 02/24/2014] [Accepted: 03/09/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Emine Soydaş
- Department of Chemistry; Atatürk University; Erzurum 25240 Turkey
| | - Uğur Bozkaya
- Department of Chemistry; Atatürk University; Erzurum 25240 Turkey
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12
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McKee WC, Schleyer PVR. Correlation Effects on the Relative Stabilities of Alkanes. J Am Chem Soc 2013; 135:13008-14. [DOI: 10.1021/ja403934s] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- William C. McKee
- Center for
Computational Chemistry and Department of
Chemistry, University of Georgia, Athens,
Georgia 30602, United States
| | - Paul von Ragué Schleyer
- Center for
Computational Chemistry and Department of
Chemistry, University of Georgia, Athens,
Georgia 30602, United States
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13
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Kemnitz CR. Electron Delocalization Explains much of the Branching and Protobranching Stability. Chemistry 2013; 19:11093-5. [DOI: 10.1002/chem.201302549] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Soydaş E, Bozkaya U. Assessment of Orbital-Optimized Third-Order Møller–Plesset Perturbation Theory and Its Spin-Component and Spin-Opposite Scaled Variants for Thermochemistry and Kinetics. J Chem Theory Comput 2013; 9:1452-60. [DOI: 10.1021/ct301078q] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Emine Soydaş
- Department of Chemistry,
Atatürk University,
Erzurum 25240, Turkey
| | - Uğur Bozkaya
- Department of Chemistry,
Atatürk University,
Erzurum 25240, Turkey
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15
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Chan B, Radom L. BDE261: a comprehensive set of high-level theoretical bond dissociation enthalpies. J Phys Chem A 2012; 116:4975-86. [PMID: 22587308 DOI: 10.1021/jp302542z] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We have used the high-level W1w protocol to compile a comprehensive collection of 261 bond dissociation enthalpies (BDEs) for bonds connecting hydrogen, first-row and second-row p-block elements. Together they cover 45 bond types, and we term this the BDE261 set. We have used these benchmark values to assess the performance of computationally less demanding theoretical procedures, including density functional theory (DFT), double-hybrid DFT (DHDFT), and high-level composite procedures. We find that the M06-2X (DFT), ROB2-PLYP and DuT-D3 (DHDFT), and G3X(MP2)-RAD and G4(MP2)-6X (composite) procedures yield absolute BDEs with satisfactory to excellent accuracy. Overall, we recommend G4(MP2)-6X as an accurate and relatively cost-effective procedure for the direct computation of BDEs. One important finding is that the deviations for DFT and (especially) DHDFT procedures are often quite systematic. This allows an alternative approach to obtaining accurate absolute BDEs, namely, to evaluate accurate relative BDEs (RBDEs) using a computationally less demanding procedure, and to use these RBDEs in combination with appropriate and accurate reference BDEs to give accurate absolute BDEs. We recommend DuT-D3 for this purpose. For a still less computationally demanding approach, we introduce the deviation from additivity of the RBDE (DARBDE), and demonstrate that the combination of lower-level DARBDEs for larger systems and higher-level (W1w) reference RBDEs and BDEs for small systems can be utilized to obtain improved RBDEs for multiply substituted systems at low cost.
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Affiliation(s)
- Bun Chan
- School of Chemistry and ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, University of Sydney, Sydney, NSW 2006, Australia.
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16
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Wodrich MD, Corminboeuf C, Wheeler SE. Accurate Thermochemistry of Hydrocarbon Radicals via an Extended Generalized Bond Separation Reaction Scheme. J Phys Chem A 2012; 116:3436-47. [DOI: 10.1021/jp212209q] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Matthew D. Wodrich
- Institut des Sciences et Ingénierie
Chimiques, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Clémence Corminboeuf
- Institut des Sciences et Ingénierie
Chimiques, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Steven E. Wheeler
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
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17
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Fattahi A, Lis L, Tehrani ZA, Marimanikkuppam SS, Kass SR. Experimental and Computational Bridgehead C–H Bond Dissociation Enthalpies. J Org Chem 2012; 77:1909-14. [DOI: 10.1021/jo202519w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Alireza Fattahi
- Department
of Chemistry, Sharif University of Technology, Tehran, Iran
| | - Lev Lis
- Department
of Chemistry, University of Minnesota,
Minneapolis, Minnesota 55455,
United States
| | - Zahra A. Tehrani
- Department
of Chemistry, Sharif University of Technology, Tehran, Iran
| | | | - Steven R. Kass
- Department
of Chemistry, University of Minnesota,
Minneapolis, Minnesota 55455,
United States
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18
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Gonthier JF, Steinmann SN, Wodrich MD, Corminboeuf C. Quantification of “fuzzy” chemical concepts: a computational perspective. Chem Soc Rev 2012; 41:4671-87. [DOI: 10.1039/c2cs35037h] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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19
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Astolfi P, Stipa P. Synthesis and Thermal Stability of Benzoxazine Nitroxides. J Org Chem 2011; 76:9253-60. [DOI: 10.1021/jo2014559] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Paola Astolfi
- S.I.M.A.U. Department - Chemistry Division, Università Politecnica delle Marche, via Brecce Bianche, I-60131 Ancona, Italy
| | - Pierluigi Stipa
- S.I.M.A.U. Department - Chemistry Division, Università Politecnica delle Marche, via Brecce Bianche, I-60131 Ancona, Italy
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