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Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory. CHEMISTRY 2021. [DOI: 10.3390/chemistry3010006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The [3+2] cycloaddition (32CA) reactions of strongly nucleophilic norbornadiene (NBD), with simplest diazoalkane (DAA) and three DAAs of increased electrophilicity, have been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G (d,p) computational level. These pmr-type 32CA reactions follow an asynchronous one-step mechanism with activation enthalpies ranging from 17.7 to 27.9 kcal·mol−1 in acetonitrile. The high exergonic character of these reactions makes them irreversible. The presence of electron-withdrawing (EW) substituents in the DAA increases the activation enthalpies, in complete agreement with the experimental slowing-down of the reactions, but contrary to the Conceptual DFT prediction. Despite the nucleophilic and electrophilic character of the reagents, the global electron density transfer at the TSs indicates rather non-polar 32CA reactions. The present MEDT study establishes the depopulation of the N–N–C core in this series of DAAs with the increase of the EW character of the substituents present at the carbon center is responsible for the experimentally found deceleration.
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2
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ALTUNDAS A. Bromination of 1,2-Dimethylenecyclohexane: Temperature Effect on Product Distribution. GAZI UNIVERSITY JOURNAL OF SCIENCE 2019. [DOI: 10.35378/gujs.466697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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3
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Uzundumlu E, Daştan A. Bromination of Endo- and Exo-benzocyclobutenonorbornene Derivatives: Neighbour Group Effect on Bromination. JOURNAL OF CHEMICAL RESEARCH 2019. [DOI: 10.3184/0308234054506901] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The electrophilic addition of bromine to 13-anti-bromo-endo-benzocyclobutenonorbornene 7 at −50 ± 5 °C has led in high yield to the formation of the rearranged dibromides 9, 10 and 11. In addition to this, bromination of exo isomer 8 results in formation of rearranged 9 and non rearranged product 10. However, high-temperature bromination of endo 7 and exo isomer 8 at 77 °C gave only non-rearranged products. The possible role of a substituent in rearrangements is discussed in these systems.
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Affiliation(s)
- Eren Uzundumlu
- Department of Chemistry, Atatürk University, 25240 Erzurum, Turkey
| | - Arif Daştan
- Department of Chemistry, Atatürk University, 25240 Erzurum, Turkey
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Daştan A. Bromination of Isomeric 7,8-dibromobenzobicyclo[2.2.2]octa-2,5-dienes: Neighbouring Group Effect on Bromination. JOURNAL OF CHEMICAL RESEARCH 2019. [DOI: 10.3184/030823405774308835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The bromination reactions of isomeric 7,8-dibromobenzobicyclo[2.2.2]octa-2,5-dienes were studied and the possible role of neighbouring groups in rearrangements was investigated. Bromination of endo-cis dibromide 9 gives only the rearranged product 14 while the reaction of the exo-cis-dibromide 11 under the same conditions gives only non-rearranged products 15, 16 and 19. The possible role of substituents in the rearrangements was discussed.
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Affiliation(s)
- Arif Daştan
- Department of Chemistry, Atatürk University, 25240 Erzurum, Turkey
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Essiz S, Dalkilic E, Sari O, Dastan A, Balci M. Unexpected regioselectivity observed in the bromination and epoxidation reactions of p-benzoquinone-fused norbornadiene: An experimental and computational study. Tetrahedron 2017. [DOI: 10.1016/j.tet.2017.02.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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DFT and MP2 study on the electrophilic addition reaction of bromine to exo-tricyclo[3.2.1.0(2.4)]oct-6-ene. J Mol Model 2009; 16:781-8. [PMID: 19904565 DOI: 10.1007/s00894-009-0608-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 09/28/2009] [Indexed: 10/20/2022]
Abstract
The geometry and electronic structure of exo-tricyclo[3.2.1.0(2,4)]oct-6-ene (exo-TCO) was investigated using DFT methods. The two faces of the endo-pyramidalised double bond of the molecule are not equivalent. The exo face of the double bond has regions with high electron density (q (i,HOMO)) and greater negative potential. Molecular complexes of exo-TCO with bromine were investigated using the B3LYP/6-311++G(d,p) method; the exo-TCO . . . Br(2)(exo) molecular complex was found to be relatively more stable than the exo-TCO . . . Br(2)(endo) complex. The cationic intermediates of the reaction were studied by DFT and MP2 methods. The solvent effect was evaluated using the self-consistent isodensity polarised continuum model (SCI-PCM). The exo-bromonium cation was found to be more stable than the endo-bromonium cation. Exo-facial selectivity due to electronic and steric factors was observed upon addition of bromine to exo-TCO. The multicentre nonclassical delocalised bromocarbonium cation IV and the exo-bridged-bromonium cation I are more stable than the rearrangement cation V. The reaction products are formed via exo-bridged-bromonium I and nonclassical IV cations, which are the most stable intermediates and whose stabilities barely differ. The mechanism of the addition reaction is also discussed.
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Nişanci B, Dalkiliç E, Güney M, Daştan A. Synthesis and Diels-Alder cycloaddition reaction of norbornadiene and benzonorbornadiene dimers. Beilstein J Org Chem 2009; 5:39. [PMID: 19777139 PMCID: PMC2748719 DOI: 10.3762/bjoc.5.39] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Accepted: 08/07/2009] [Indexed: 11/23/2022] Open
Abstract
Dimeric forms of norbornadiene and benzonorbornadiene were synthesized starting with known monobromide derivatives. The Diels–Alder cycloaddition reaction of dimers with TCNE and PTAD was investigated and new norbornenoid polycyclics were obtained. All compounds were characterized properly using NMR spectroscopy.
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Affiliation(s)
- Bilal Nişanci
- Atatürk University, Faculty of Science, Department of Chemistry, 25240 Erzurum-TURKEY
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Gültekin DD, Taşkesenligil Y, Daştan A, Balci M. Bromination of norbornene derivatives: synthesis of brominated norbornanes and norbornenes. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.02.067] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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9
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Balci M, Güney M, Daştan A, Azizoğlu A. The Effect of the Double Bond Pyramidalization on the Mode of the Bromination Reaction: Bromination of Benzobicyclononadiene. J Org Chem 2007; 72:4756-62. [PMID: 17521198 DOI: 10.1021/jo070253b] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The bromination of 6,7,8,9-tetrahydro-5H-5,9-ethenobenzo[a][7]annulene yielded regio- and stereospecifically formed dibromides arising from the alkyl shift where the bromine exclusively attacks the double bond from the endo face of the double bond. DFT calculations on model compounds showed that the pyramidalization of the double bond and steric repulsion caused by the methylene protons are responsible for the stereo- and regioselective addition of bromine.
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Affiliation(s)
- Metin Balci
- Department of Chemistry, Middle East Technical University, 06531 Ankara, Turkey.
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Kishali NH, Sahin E, Kara Y. An Intramolecular Substitution of Hydroperoxy-endoperoxide to a Bis-endoperoxide. Org Lett 2006; 8:1791-3. [PMID: 16623552 DOI: 10.1021/ol060272s] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] A new and stereospecific synthesis for bis-endoperoxide has been developed starting from tetrahydronaphthalene. Photooxygenation of tetrahydronaphthalene resulted in the formation of hydroperoxy-endoperoxide. The bromination reaction of hydroperoxy-endoperoxide gave bis-endoperoxide, whose exact configuration has been determined by X-ray analysis. The lowest-energy conformer of bis-endoperoxide is the boat-chair form.
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Affiliation(s)
- Nurhan Horasan Kishali
- Department of Chemistry, Faculty of Arts and Sciences, Atatürk University, 25240 Erzurum, Turkey.
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Abbasoglu R, Yilmaz SS. Ab initio and DFT study on the electrophilic addition of bromine to endo-tricyclo[3.2.1.0(2,4)]oct-6-ene. J Mol Model 2005; 12:290-6. [PMID: 16249937 DOI: 10.1007/s00894-005-0031-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2004] [Accepted: 07/05/2005] [Indexed: 11/24/2022]
Abstract
Full geometric optimization of endo-tricyclo[3.2.1.0(2,4)]oct-6-ene (endo-TCO) by ab initio and DFT methods allowed us to investigate the structure of the molecule. The double bond is endo-pyramidalized and its two faces are no longer found to be equivalent. The exo face of the double bond has regions with far more electron density (q(i,HOMO)) and more negative electrostatic potential. The endo-TCO-Br2 system was investigated at the B3LYP/6-311+G** level and the endo-TCO...Br2(exo) molecular complex was found to be relatively more stable than the endo-TCO...Br2(endo) complex. The cationic intermediates of the reaction were studied by ab initio and DFT methods. The bridged exo-bromonium cation(I) is relatively more stable than the endo-bromonium cation(II). An absolute exo-facial selectivity should be observed in the addition reaction of Br2 to endo-TCO, which is caused by steric and electronic factors. The nonclassical rearranged cation IV was found to be the most stable ion among the cationic intermediates and the ionic addition occurs via the formation of this cation. The mechanism of the addition reaction is also discussed.
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Affiliation(s)
- Rza Abbasoglu
- Department of Chemistry, Karadeniz Technical University, 61080, Trabzon, Turkey.
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Kuznetsov ML, Nazarov AA, Pombeiro AJL. Protic Conversion of Nitrile into Azavinylidene Complexes of Rhenium, a Mechanistic Theoretical Study. J Phys Chem A 2005; 109:8187-98. [PMID: 16834205 DOI: 10.1021/jp0527913] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mechanism of the protonation of the rhenium nitrile chloro-complexes [ReCl(NCCH3)(PH3)4] (2), taken as models of the real systems [ReCl(NCR)(dppe)(2)] (dppe = Ph2PCH2CH2PPh2), leading to the azavinylidene products [ReCl(NC(H)CH3)(PH3)4]+ (3) was investigated by theoretical methods at the B3LYP level of theory. Electrostatic and molecular orbital arguments and thermodynamic, kinetic, and steric factors are analyzed and indicate that the chlorine atom is the most probable site of the initial proton attack, although the direct protonation of the nitrile carbon atom is also possible as a concurrent process. For the cis-isomer of 2, the initially formed chloro-protonated species cis-[Re(ClH)(NCCH3)(PH3)4]+ further converts to the azavinylidene cis-3 via either an acid-independent 1,4-proton shift or an acid-base catalyzed pathway involving a second protonation of the nitrile carbon atom to give cis-[Re(ClH)(NC(H)CH3)(PH3)4]2+ followed by elimination of the proton from the chlorine atom.
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Affiliation(s)
- Maxim L Kuznetsov
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
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High temperature bromination. Part 18: Bromination of benzonorbornadiene derivatives: Polybrominated benzonorbornenes and benzonorbornadienes. Tetrahedron 2005. [DOI: 10.1016/j.tet.2005.03.132] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Kazaz C, Daştan A, Balci M. Synthesis and structure elucidation of bromination products from dibromohomobenzonorbornadienes: high temperature bromination--part 17. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:75-81. [PMID: 15390027 DOI: 10.1002/mrc.1490] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The electrophilic addition of bromine to dibromohomobenzonorbornadiene derivatives at -45 +/- 5 degrees C led to the formation of the rearranged and non-rearranged tetrabromides in a ratio of 6:4. However, high-temperature bromination of the same system in CCl4 at 77 degrees C produced only non-rearranged products. The formation mechanism of the isomers and the role of the substituent on the rearrangement is discussed. The structure elucidation of the isomeric tetrabromides was achieved from NMR spectral data. The agreement between the calculated dihedral angles and the measured coupling constants is especially excellent. The gamma-gauche effect is discussed.
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Affiliation(s)
- Cavit Kazaz
- Atatürk University, Department of Chemistry, 25240 Erzurum, Turkey
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Xi Z, Liu X, Lu J, Bao F, Fan H, Li Z, Takahashi T. Synthesis of 1,1,4,4-Tetrabromo-2-butenes and Related Compounds via Desilylation−Bromination of Silylated 1,3-Butadiene Derivatives. J Org Chem 2004; 69:8547-9. [PMID: 15549842 DOI: 10.1021/jo048940f] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The combination of zirconocene-mediated coupling of silylated alkynes with a protonation-desilylation or bromination-desilylation process afforded otherwise unavailable butadiene derivatives. When (E,E)-2,3-dialkyl-1,4-bis(trimethylsilyl)-1,3-butadienes were treated with 3 equiv of Br(2) in CH(2)Cl(2), (E)-2,3-dialkyl-1,1,4,4-tetrabromo-2-butenes were obtained in excellent yields with perfect stereoselectivity.
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Affiliation(s)
- Zhenfeng Xi
- Peking University-Hokkaido University Joint Lab, College of Chemistry, Peking University, Beijing 100871, China
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