1
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Ippoliti FM, Adamson NJ, Wonilowicz LG, Nasrallah DJ, Darzi ER, Donaldson JS, Garg NK. Total synthesis of lissodendoric acid A via stereospecific trapping of a strained cyclic allene. Science 2023; 379:261-265. [PMID: 36656952 PMCID: PMC10462259 DOI: 10.1126/science.ade0032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 11/18/2022] [Indexed: 01/21/2023]
Abstract
Small rings that contain allenes are unconventional transient compounds that have been known since the 1960s. Despite being discovered around the same time as benzyne and offering a number of synthetically advantageous features, strained cyclic allenes have seen relatively little use in chemical synthesis. We report a concise total synthesis of the manzamine alkaloid lissodendoric acid A, which hinges on the development of a regioselective, diastereoselective, and stereospecific trapping of a fleeting cyclic allene intermediate. This key step swiftly assembles the azadecalin framework of the natural product, allows for a succinct synthetic endgame, and enables a 12-step total synthesis (longest linear sequence; 0.8% overall yield). These studies demonstrate that strained cyclic allenes are versatile building blocks in chemical synthesis.
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Affiliation(s)
| | | | - Laura G. Wonilowicz
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Daniel J. Nasrallah
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | | | | | - Neil K. Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
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2
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Dauvergne G, Vanthuyne N, Giorgi M, Rodriguez J, Carissan Y, Coquerel Y. Determination of the Rate Constant of the [4 + 2] Cycloaddition Between an Aryne Atropisomer and Furan in Solution. J Org Chem 2022; 87:11141-11147. [PMID: 35946800 DOI: 10.1021/acs.joc.2c01394] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using a specially designed prototype of a nonracemic aryne atropisomer with a low barrier to enantiomerization (ca. 36 kJ·mol-1), it was possible to determine the kinetic constant of its cycloaddition with furan in solution by a combination of theoretical calculations and experimental measurements. It was found that the reaction half-life of this aryne atropisomer in solution with 100 equivalents of furan as the trapping reagent is <150 ns at temperatures above -20 °C.
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Affiliation(s)
| | - Nicolas Vanthuyne
- Aix Marseille Univ, CNRS, Centrale Marseille, ISM2, Marseille, France
| | - Michel Giorgi
- Aix Marseille Univ, CNRS, Centrale Marseille, FSCM, Marseille, France
| | - Jean Rodriguez
- Aix Marseille Univ, CNRS, Centrale Marseille, ISM2, Marseille, France
| | - Yannick Carissan
- Aix Marseille Univ, CNRS, Centrale Marseille, ISM2, Marseille, France
| | - Yoann Coquerel
- Aix Marseille Univ, CNRS, Centrale Marseille, ISM2, Marseille, France
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3
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Saraswat M, Ravi S, Shamasundar KR, Venkataramani S. Photochemistry of 3,6-Didehydropyridazine Biradical─An Untraceable Para Benzyne Analogue. J Phys Chem A 2022; 126:557-567. [PMID: 35049300 DOI: 10.1021/acs.jpca.1c09317] [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
We report matrix isolation infrared spectroscopic studies to characterize 3,6-didehydropyridazine 6, a heterocyclic analogue of para benzyne, combined with computations. In this regard, we have utilized 3,6-diiodopyridazine 11 as a photolytic precursor. The experiments toward the generation of the biradical are carried out in argon and nitrogen matrices at 4 K. Instead of the elusive biradical, we have observed a ring-opening product maleonitrile (Z)-7 upon irradiation at 254 nm. In contrast, prolonged irradiation at 254 nm leads only to Z-E isomerization, forming fumaronitrile (E)-7. The mechanistic aspects of ring-opening, product selectivity, and Z-E photoisomerization steps have been investigated in detail using high-level ab initio computations. These studies have found that 3,6-didehydropyridazine 6 is an untraceable intermediate, and the ring-opening step leading to maleonitrile is barrierless. In addition, we have proposed the involvement of the S1 (π-π*) state via conical intersection in the Z-E photoisomerization of maleonitrile.
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Affiliation(s)
- Mayank Saraswat
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Mohali Knowledge City, Sector 81, SAS Nagar, Manauli 140306, India
| | | | - K R Shamasundar
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Mohali Knowledge City, Sector 81, SAS Nagar, Manauli 140306, India
| | - Sugumar Venkataramani
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Mohali Knowledge City, Sector 81, SAS Nagar, Manauli 140306, India
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4
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Behera B, Das P. HCl elimination in the photolysis of chlorobenzene at 266 nm: An FT-IR spectroscopy and quantum chemical study. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Intercepting fleeting cyclic allenes with asymmetric nickel catalysis. Nature 2020; 586:242-247. [PMID: 32846425 DOI: 10.1038/s41586-020-2701-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 08/12/2020] [Indexed: 12/21/2022]
Abstract
Strained cyclic organic molecules, such as arynes, cyclic alkynes and cyclic allenes, have intrigued chemists for more than a century with their unusual structures and high chemical reactivity1. The considerable ring strain (30-50 kilocalories per mole)2,3 that characterizes these transient intermediates imparts high reactivity in many reactions, including cycloadditions and nucleophilic trappings, often generating structurally complex products4. Although strategies to control absolute stereochemistry in these reactions have been reported using stoichiometric chiral reagents5,6, catalytic asymmetric variants to generate enantioenriched products have remained difficult to achieve. Here we report the interception of racemic cyclic allene intermediates in a catalytic asymmetric reaction and provide evidence for two distinct mechanisms that control absolute stereochemistry in such transformations: kinetic differentiation of allene enantiomers and desymmetrization of intermediate π-allylnickel complexes. Computational studies implicate a catalytic mechanism involving initial kinetic differentiation of the cyclic allene enantiomers through stereoselective olefin insertion, loss of the resultant stereochemical information, and subsequent introduction of absolute stereochemistry through desymmetrization of an intermediate π-allylnickel complex. These results reveal reactivity that is available to cyclic allenes beyond the traditional cycloadditions and nucleophilic trappings previously reported, thus expanding the types of product accessible from this class of intermediates. Additionally, our computational studies suggest two potential strategies for stereocontrol in reactions of cyclic allenes. Combined, these results lay the foundation for the development of catalytic asymmetric reactions involving these classically avoided strained intermediates.
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6
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Lee S, Ree J. Effects of the Substituents on the Energy Flow of Toluene Derivatives in Collisions with N
2
and O
2. B KOREAN CHEM SOC 2019. [DOI: 10.1002/bkcs.11841] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Su‐jin Lee
- Department of Chemistry EducationChonnam National University Gwangju 61186 South Korea
| | - Jongbaik Ree
- Department of Chemistry EducationChonnam National University Gwangju 61186 South Korea
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7
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Liu B, Zhao H, Lin X, Li X, Gao M, Wang L, Wang W. Vibronic relaxation dynamics of o-dichlorobenzene in its lowest excited singlet state. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2017.12.058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Jeong YJ, Ree J, Kim YH, Shin HK. Energy Transfer and Bond Dissociation in the o
-chlorotoluene + H 2
/Cl 2
/HCl Collisions. B KOREAN CHEM SOC 2017. [DOI: 10.1002/bkcs.11201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Yun Jeong Jeong
- Department of Chemistry Education; Chonnam National University; Gwangju 61186 Korea
| | - Jongbaik Ree
- Department of Chemistry Education; Chonnam National University; Gwangju 61186 Korea
| | - Yoo Hang Kim
- Department of Chemistry; Inha University; Incheon 22212 Korea
| | - Hyung Kyu Shin
- Department of Chemistry; University of Nevada; Reno Nevada 89557 USA
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9
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Dou J, Sun Z, Opalade AA, Wang N, Fu W, Tao F(F. Operando chemistry of catalyst surfaces during catalysis. Chem Soc Rev 2017; 46:2001-2027. [DOI: 10.1039/c6cs00931j] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The chemistry of a catalyst surface during catalysis is crucial for a fundamental understanding of the mechanisms of a catalytic reaction performed on the catalyst in the gas or liquid phase.
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Affiliation(s)
- Jian Dou
- Department of Chemical and Petroleum Engineering and Department of Chemistry
- University of Kansas
- Lawrence
- USA
| | - Zaicheng Sun
- Department of Chemistry and Chemical Engineering
- Beijing University of Technology
- Beijing
- China
| | - Adedamola A. Opalade
- Department of Chemical and Petroleum Engineering and Department of Chemistry
- University of Kansas
- Lawrence
- USA
| | - Nan Wang
- Department of Chemical and Petroleum Engineering and Department of Chemistry
- University of Kansas
- Lawrence
- USA
| | - Wensheng Fu
- Chongqing Key Laboratory of Green Synthesis and Applications and College of Chemistry
- Chongqing Normal University
- Chongqing
- China
| | - Franklin (Feng) Tao
- Department of Chemical and Petroleum Engineering and Department of Chemistry
- University of Kansas
- Lawrence
- USA
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10
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Torres-Alacan J. Photolysis of a Benzyne Precursor Studied by Time-Resolved FTIR Spectroscopy. J Org Chem 2016; 81:1151-6. [PMID: 26760219 DOI: 10.1021/acs.joc.5b02678] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The 266 nm laser flash photolysis of phtaloyl peroxide (2) in liquid acetonitrile solution at room temperature has been investigated. Upon 266 nm laser irradiation, 2 is effectively photodecarboxylated leading to the formation of o-benzyne (1) and two equivalents of CO2, yet a small fraction of photolyzed 2 follows a different pathway leading to 6-oxocyclohexa-2,4-dienylideneketene (3) and one equivalent of CO2. Compound 3 is kinetically reactive and reacts in the microsecond time scale following a first-order kinetic law. The presence of 1 in the photolysis experiment is confirmed by trapping experiments with methyl 1-methylpyrrole-2-carboxylate (6). The Diels-Alder reaction between 1 and 6 occurs under the selected experimental conditions on a time scale shorter than 100 ms.
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Affiliation(s)
- Joel Torres-Alacan
- Institute for Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universtität , Wegelerstraße 12, 53115 Bonn, Germany
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11
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Edel K, Fink RF, Bettinger HF. Isomerization and fragmentation pathways of 1,2-azaborine. J Comput Chem 2015; 37:110-6. [PMID: 26418051 DOI: 10.1002/jcc.24189] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 11/11/2022]
Abstract
The generation of 1,2-azaborine (4), the BN-analogue of ortho-benzyne, was recently achieved by elimination of tert-butyldimethylchlorosilane under the conditions of flash vacuum pyrolysis. The present investigation identifies by computational means pathways for the thermal isomerization and fragmentation of 1,2-azaborine. The computations were performed using single reference (hybrid/density functional, second order Møller-Plesset perturbation, and coupled cluster theories) as well as multiconfiguration methods (complete active space SCF based second order perturbation theory, multireference configuration interaction, and multiconfiguration coupled electron pair approximation) with basis sets up to polarized triple-ζ quality. The 1,2-azaborine is, despite the distortion of its molecular structure, the most stable C4H4BN isomer investigated. The formation of BN-endiyne isomers is highly unfavorable as the identified pathways involve barriers close to 80 kcal mol(-1). The concerted fragmentation to ethyne and 2-aza-3-bora-butadiyne even has a barrier close to 120 kcal mol(-1). The fragmentation of BN-enediynes has energetic requirements similar to enediynes.
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Affiliation(s)
- Klara Edel
- Institut Für Organische Chemie, Universität Tübingen, Auf Der Morgenstelle 18, Tübingen, 72076, Germany
| | - Reinhold F Fink
- Institut Für Physikalische Und Theoretische Chemie, Universität Tübingen, Auf Der Morgenstelle 18, Tübingen, 72076, Germany
| | - Holger F Bettinger
- Institut Für Organische Chemie, Universität Tübingen, Auf Der Morgenstelle 18, Tübingen, 72076, Germany
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12
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Chai Y, Shen S, Weng G, Pan Y. Gas-phase synthesis and reactivity of Cu+–benzyne complexes. Chem Commun (Camb) 2014; 50:11668-71. [DOI: 10.1039/c4cc04168b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cu+–benzyne complexes bearing ligands (L) were synthesized and their addition reactivity was studied in the gas phase using electrospray ionization ion trap mass spectrometry.
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Affiliation(s)
- Yunfeng Chai
- Department of Chemistry
- Zhejiang University
- Hangzhou, China
| | - Shanshan Shen
- Department of Chemistry
- Zhejiang University
- Hangzhou, China
| | - Guofeng Weng
- Department of Chemistry
- Zhejiang University
- Hangzhou, China
| | - Yuanjiang Pan
- Department of Chemistry
- Zhejiang University
- Hangzhou, China
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13
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Fulara J, Nagy A, Filipkowski K, Thimmakondu VS, Stanton JF, Maier JP. Electronic Transitions of C6H4+ Isomers: Neon Matrix and Theoretical Studies. J Phys Chem A 2013; 117:13605-15. [DOI: 10.1021/jp407566h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jan Fulara
- Department
of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Adam Nagy
- Department
of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Karol Filipkowski
- Department
of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Venkatesan S. Thimmakondu
- Department
of Chemistry and Biochemistry, The University of Texas at Austin, 1
University Station A5300, Austin, Texas 78712-0165, United States
| | - John F. Stanton
- Department
of Chemistry and Biochemistry, The University of Texas at Austin, 1
University Station A5300, Austin, Texas 78712-0165, United States
| | - John P. Maier
- Department
of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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14
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Zhu W, Yuan Y, Zhou P, Zeng L, Wang H, Tang L, Guo B, Chen B. The expanding role of electrospray ionization mass spectrometry for probing reactive intermediates in solution. Molecules 2012; 17:11507-37. [PMID: 23018925 PMCID: PMC6268401 DOI: 10.3390/molecules171011507] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 08/29/2012] [Accepted: 09/05/2012] [Indexed: 12/31/2022] Open
Abstract
Within the past decade, electrospray ionization mass spectrometry (ESI-MS) has rapidly occupied a prominent position for liquid-phase mechanistic studies due to its intrinsic advantages allowing for efficient "fishing" (rapid, sensitive, specific and simultaneous detection/identification) of multiple intermediates and products directly from a "real-world" solution. In this review we attempt to offer a comprehensive overview of the ESI-MS-based methodologies and strategies developed up to date to study reactive species in reaction solutions. A full description of general issues involved with probing reacting species from complex (bio)chemical reaction systems is briefly covered, including the potential sources of reactive intermediate (metabolite) generation, analytical aspects and challenges, basic rudiments of ESI-MS and the state-of-the-art technology. The main purpose of the present review is to highlight the utility of ESI-MS and its expanding role in probing reactive intermediates from various reactions in solution, with special focus on current progress in ESI-MS-based approaches for improving throughput, testing reality and real-time detection by using newly developed MS instruments and emerging ionization sources (such as ambient ESI techniques). In addition, the limitations of modern ESI-MS in detecting intermediates in organic reactions is also discussed.
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Affiliation(s)
- Weitao Zhu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Yu Yuan
- School of Pharmaceutical Sciences, Central South University, 172 Tongzipo Road, Changsha 410013, China;
| | - Peng Zhou
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Le Zeng
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Hua Wang
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Ling Tang
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Bin Guo
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Bo Chen
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
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15
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Spiteri C, Mason C, Zhang F, Ritson DJ, Sharma P, Keeling S, Moses JE. An efficient entry to 1,2-benzisoxazoles via 1,3-dipolar cycloaddition of in situ generated nitrile oxides and benzyne. Org Biomol Chem 2010; 8:2537-42. [PMID: 20372741 DOI: 10.1039/b927235f] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An efficient protocol for the synthesis of a range of 1,2-benzisoxazoles using an improved 1,3-dipolar cycloaddition of nitrile oxides and benzyne is described. Key to the procedure is the in situ generation of the reactive nitrile oxide and benzyne reactants simultaneously.
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Affiliation(s)
- Christian Spiteri
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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16
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Abstract
The history of o-benzyne from its early beginnings as an unobservable reactive intermediate until its present status as a very well characterized but still theoretically challenging molecule with important applications in synthesis is reviewed. The m- and p-benzynes, tridehydrobenzenes, and benzdiynes are also known, and p-benzyne is a key intermediate in the action of a potent class of ene-diyne anti-tumour compounds.
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17
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Monsandl T, Macfarlane G, Flammang R, Wentrup C. Mass Spectrometry of Benzyne and Cyclopentadienylideneketene. Aust J Chem 2010. [DOI: 10.1071/ch09640] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The formation of cyclopentadienylideneketene 2 and benzyne 1 in flash vacuum thermolysis reactions is investigated by on-line mass spectrometry. Compounds 13, 14, and 15 all afford ketene 2, which decomposes to benzyne and CO in the high-temperature regime. Cyclopentadienylideneketene 2 is stable on the microsecond time-scale of neutralization-reionization experiments. Collisional activation mass spectrometry of m/z 76 from 14, 15, and 5 indicates that the C6H4•+ ions most likely undergo ring opening in the mass spectrometer.
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18
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Friedrichs G, Goos E, Gripp J, Nicken H, Schönborn JB, Vogel H, Temps F. The Products of the Reactions of o-Benzyne with Ethene, Propene, and Acetylene: A Combined Mass Spectrometric and Quantum Chemical Study. Z PHYS CHEM 2009. [DOI: 10.1524/zpch.2009.6042] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The primary products of the bimolecular reactions of ortho-benzyne, o-C6H4 (1,2-dehydrobenzene), with ethene, propene, and acetylene have been detected by molecular beam mass spectrometry at a combustion relevant temperature of T = 1475 K. o-Benzyne was produced by flash pyrolysis of phthalic anhydride in the absence and presence of the respective reactant. Potential reaction pathways of the addition reactions were investigated by quantum chemical calculations. Channels with biradical intermediates were found to be energetically more favorable than alternative quasi-concerted [2+1] cycloaddition and concerted H-transfer pathways. Bicyclic benzocyclobutene and benzocyclobutadiene were identified as the main products of the reactions with C2H4 and C2H2, respectively. At combustion temperatures, however, these cyclic products are likely to undergo sequential ring opening. In the case of propene, the presence of an allylic H atom initiates a favorable ene-type reaction sequence yielding the open-chain product allylbenzene. Overall, hydrocarbon reactivity was found to increase in the order C2H2, C2H4 to 3H8. The range of the estimated bimolecular rate constants is comparable to the rate constants of the corresponding phenyl radical reactions and hence point out a potentially important role of o-C6H4 reactions in flame and soot formation chemistry.
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Affiliation(s)
| | | | | | | | | | | | - Friedrich Temps
- Christian-Albrechts-Universität, Institut für Physikalische Chemie, Kiel, Deutschland
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19
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Yuan LW, Zhu JY, Wang YQ, Wang L, Bai JL, He GZ. Real-time investigation of the photodissociation dynamics of p-chlorotoluene and p-dichlorobenzene. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.05.103] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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20
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Winkler M, Cakir B, Sander W. 3,5-PyridyneA Heterocyclic meta-Benzyne Derivative. J Am Chem Soc 2004; 126:6135-49. [PMID: 15137779 DOI: 10.1021/ja039142u] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
3,5-Pyridyne (3) has been generated by flash vacuum pyrolysis of 3,5-diiodopyridine (20) and 3,5-dinitropyridine (21) and characterized by IR spectroscopy in cryogenic argon matrices. The aryne can clearly be distinguished from other side products by its photolability at 254 nm, inducing a rapid ring-opening presumably to (Z)-1-aza-hex-3-ene-1,5-diyne. As byproducts of the pyrolysis, HCN and butadiyne were identified, together with traces of acetylene, cyanoacetylene, (E)-1-aza-hex-3-ene-1,5-diyne, and the 3-iodo-5-pyridyl radical (from 20). Several pathways for rearrangements and fragmentations of 3 and of the parent meta-benzyne (1) have been explored computationally by density functional theory and ab initio quantum chemical methods. The lowest energy decomposition pathway of biradicals 1 and 3 is a ring-opening process accompanied by hydrogen migration, leading to (Z)-hex-3-ene-1,5-diyne [(Z)-10] and (Z)-3-aza-hex-3-ene-1,5-diyne [(Z)-24], respectively. Both reactions require activation energies of 45-50 kcal mol(-1). Mechanisms leading from (Z)-24 or directly from 3 to the experimentally observed byproducts are discussed. Upon replacement of the C(5)H moiety by N in meta-benzyne, high-level calculations predict a modest shortening of the interradical distance by 5-7 pm and a reduction of the singlet-triplet energy splitting by 3 kcal mol(-1), in good agreement with isodesmic equations, according to which the singlet ground state of 3 is destabilized relative to 1 by 3-4 kcal mol(-1). In contrast to 3,5-borabenzyne (2), which is found to be doubly aromatic, nucleus-independent chemical shifts of 3 are almost identical to that of pyridine, indicating the absence of paramagnetic ring current effects that may be associated with "in-plane antiaromaticity". As compared with 1, the overall perturbation caused by the nitrogen atom in 3 is weak, and four electron, three center interaction is of minor importance in this molecule.
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Affiliation(s)
- Michael Winkler
- Lehrstuhl für Organische Chemie II der Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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21
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Liu H, Zhang X, Wang C, Guo W, Wu Y, Yang S. Effects of Aromatic Substitutions on the Photoreactions in Mg•+(C6HnF2X4-n) (X = F, CH3) Complexes: Formation and Decomposition of Benzyne Radical Cations. J Phys Chem A 2004. [DOI: 10.1021/jp037535+] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Liu HC, Yang S, Zhang XH, Wu YD. Unusual Chemistry of the Complex Mg•+(2-Fluoropyridine) Activated by the Photoexcitation of Mg•+. J Am Chem Soc 2003; 125:12351-7. [PMID: 14519021 DOI: 10.1021/ja036476a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The photochemistry of a gas-phase complex, Mg*(+)(2-fluoropyridine), has been studied in the spectral range of approximately 230-440 nm with a molecular beam coupled with a time-of-flight mass spectrometer. Surprisingly rich chemistry has been observed. Aside from the evaporative photofragment, Mg*(+), an abundant photoproduct, C(4)H(4)*(+), is observed after the electronic excitation of Mg(+). The formation of this photoproduct is associated with the loss of a stable species, CN[bond]Mg[bond]F. Also identified in this work are reactive pathways that occur with the elimination of HCN, HF, or MgF from the complex. The observed photoreactions have been examined in detail using quantum mechanics methods. A distinct structural feature of the complex is the direct attachment of Mg*(+) to the N atom of fluoropyridine due to the strong electrostatic interaction. The key to the rich photochemistry is the formation of the FMg(+)(C(5)H(4)N) intermediate, through facile fluorine migration. Plausible photoreaction mechanisms have been proposed. These mechanisms account for the evolution of the energized complex with the pre-defined structure en route to the target photoproducts that we have detected.
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Affiliation(s)
- Hai-Chuan Liu
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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23
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Blake ME, Bartlett KL, Jones M. A m-benzyne to o-benzyne conversion through a 1,2-shift of a phenyl group. J Am Chem Soc 2003; 125:6485-90. [PMID: 12785789 DOI: 10.1021/ja0213672] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pyrolysis of two differently labeled versions of 3-phenylphthalic anhydride shows that a m-benzyne can form the related o-benzyne through shift of a phenyl group. The highest energy point in the process is the transition structure for a reverse carbon-hydrogen insertion in an intermediate benzopentalene. With the minor addition of an intermediate alkyne formed through a Roger Brown rearrangement, the original mechanism for formation of acenaphthalene accommodates the labeling results.
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Affiliation(s)
- Michael E Blake
- Contribution from the Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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24
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Mohler DL, Gray Coonce J, Predecki D. Photoinduced DNA cleavage by benzenediradical equivalents. 1,3- and 1,4-bis(dicarbonylcyclopentadienyliron)benzene. Bioorg Med Chem Lett 2003; 13:1377-9. [PMID: 12657286 DOI: 10.1016/s0960-894x(03)00097-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Upon photolysis, diiron complexes 1,4- and 1,3-Fp(2)C(6)H(4) (1 and 2) linearize plasmid DNA at ratios as low as 1.5 and 3.0 molecules/bp DNA, respectively. Additionally, single-strand cleavage was observed at ratios higher than 0.05 and 0.19 molecules/bp DNA for 1 and 2, respectively. Radical scavenging studies and metal radical control experiments implicate carbon-centered radicals as participants in the cleavage pathway.
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Affiliation(s)
- Debra L Mohler
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA.
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25
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Sander W, Exner M, Winkler M, Balster A, Hjerpe A, Kraka E, Cremer D. Vibrational spectrum of m-benzyne: a matrix isolation and computational study. J Am Chem Soc 2002; 124:13072-9. [PMID: 12405834 DOI: 10.1021/ja012686g] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
m-Benzyne (2) was generated in low-temperature matrices and IR spectroscopically characterized from four different precursors. To assign the IR absorptions, the perdeuterated derivative 2-d(4) was also investigated. By comparison with CCSD(T) calculations all vibrations between 200 and 2500 cm(-)(1) with a predicted relative intensity >2% could be assigned. All experimental and theoretical results are in accordance with a biradicaloid structure for 2, while there is no evidence for a bicyclic closed-shell structure. While benzyne 2 is stable under the conditions of matrix isolation at low temperature, flash vacuum pyrolysis at high temperatures or UV irradiation results in the rearrangement to cis-enediyne. A mechanism involving ring opening accompanied by hydrogen migration is proposed.
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Affiliation(s)
- Wolfram Sander
- Lehrstuhl für Organische Chemie II der Ruhr-Universität, D-44780 Bochum, Germany
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26
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Radziszewski JG, Waluk J, Kaszynski P, Spanget-Larsen J. High-Resolution Spectroscopic Study of Matrix-Isolated Reactive Intermediates: Vibrational Assignments for 3-Fluoro-o-Benzyne and Perfluoro-o-Benzyne∇. J Phys Chem A 2002. [DOI: 10.1021/jp0209998] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. George Radziszewski
- National Renewable Energy Laboratory (NREL), 1617 Cole Blvd. Golden, Colorado 80401, Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401, ADA Technologies, Inc., Littleton, Colorado 80127, Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland, Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, and Department of Chemistry, Roskilde University (RUC), DK-4000 Roskilde, Denmark
| | - Jacek Waluk
- National Renewable Energy Laboratory (NREL), 1617 Cole Blvd. Golden, Colorado 80401, Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401, ADA Technologies, Inc., Littleton, Colorado 80127, Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland, Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, and Department of Chemistry, Roskilde University (RUC), DK-4000 Roskilde, Denmark
| | - Piotr Kaszynski
- National Renewable Energy Laboratory (NREL), 1617 Cole Blvd. Golden, Colorado 80401, Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401, ADA Technologies, Inc., Littleton, Colorado 80127, Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland, Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, and Department of Chemistry, Roskilde University (RUC), DK-4000 Roskilde, Denmark
| | - Jens Spanget-Larsen
- National Renewable Energy Laboratory (NREL), 1617 Cole Blvd. Golden, Colorado 80401, Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado 80401, ADA Technologies, Inc., Littleton, Colorado 80127, Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland, Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, and Department of Chemistry, Roskilde University (RUC), DK-4000 Roskilde, Denmark
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27
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Liu HC, Wang CS, Guo W, Wu YD, Yang S. Formation and decomposition of distonic o-, m-, and p-benzyne radical cations from photolysis of Mg(+)(o-, m-, p-C(6)H(4)F(2)). J Am Chem Soc 2002; 124:3794-8. [PMID: 11929271 DOI: 10.1021/ja0122546] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Distonic o-, m-, and p-benzyne radical cations (1-3) have been generated by a novel photolysis reaction of mass-selected Mg(+)-difluorobenzene complexes. The energy required for the formation of these radical cations is within 2.2 eV. The formation of o-benzyne cation is most facile. The benzyne radical cations dissociate further to yield ethyne and 1,3-butadiyne radical cation as major products given a sufficient amount of energy. The whole process involves only a single photon, and is very efficient. The calculated threshold for the formation of 1,3-butadiyne radical cation from Mg(+)(o-C(6)H(4)F(2)) is about 4.6 eV, quite comparable with the experimental estimate.
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Affiliation(s)
- Hai-Chuan Liu
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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28
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Diau EWG, Kötting C, Zewail AH. Femtochemistry of Norrish Type-I Reactions: II. The Anomalous Predissociation Dynamics of Cyclobutanone on the S1 Surface. Chemphyschem 2001. [DOI: 10.1002/1439-7641(20010518)2:5%3c294::aid-cphc294%3e3.0.co;2-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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29
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Diau EWG, Kötting C, Zewail AH. Femtochemistry of Norrish Type-I Reactions: II. The Anomalous Predissociation Dynamics of Cyclobutanone on the S1 Surface. Chemphyschem 2001; 2:294-309. [DOI: 10.1002/1439-7641(20010518)2:5<294::aid-cphc294>3.0.co;2-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2000] [Indexed: 11/07/2022]
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30
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Cramer CJ, Thompson J. Quantum Chemical Characterization of Singlet and Triplet Didehydroindenes. J Phys Chem A 2001. [DOI: 10.1021/jp004379n] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher J. Cramer
- Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431
| | - Jason Thompson
- Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431
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31
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Arulmozhiraja S, Sato T, Yabe A. Benzdiynes revisited:ab initio and density functional theory. J Comput Chem 2001. [DOI: 10.1002/jcc.1055] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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32
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Affiliation(s)
- Elfi Kraka
- Contribution from the Department of Theoretical Chemistry, Göteborg University, Reutersgatan 2, S-401320 Göteborg, Sweden
| | - Dieter Cremer
- Contribution from the Department of Theoretical Chemistry, Göteborg University, Reutersgatan 2, S-401320 Göteborg, Sweden
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33
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Zewail A. Femtochemie: Studium der Dynamik der chemischen Bindung auf atomarer Skala mit Hilfe ultrakurzer Laserpulse (Nobel-Aufsatz). Angew Chem Int Ed Engl 2000. [DOI: 10.1002/1521-3757(20000804)112:15<2688::aid-ange2688>3.0.co;2-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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