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Kennedy CR, Joannou MV, Steves JE, Hoyt JM, Kovel CB, Chirik PJ. Iron-Catalyzed Vinylsilane Dimerization and Cross-Cycloadditions with 1,3-Dienes: Probing the Origins of Chemo- and Regioselectivity. ACS Catal 2021; 11:1368-1379. [PMID: 34336370 PMCID: PMC8317497 DOI: 10.1021/acscatal.0c04608] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The selective, intermolecular, homodimerization and cross-cycloaddition of vinylsilanes with unbiased 1,3-dienes, catalyzed by a pyridine-2,6-diimine (PDI) iron complex is described. In the absence of a diene coupling partner, vinylsilane hydroalkenylation products were obtained chemoselectively with unusual head-to-head regioselectivity (up to >98% purity, 98:2 E/Z). In the presence of a 4- or 2-substituted diene coupling partner, under otherwise identical reaction conditions, formation of value-added [2+2]- and [4+2]-cycloadducts, respectively, was observed. The chemoselectivity profile was distinct from that observed for analogous α-olefin dimerization and cross-reactions with 1,3-dienes. Mechanistic studies conducted with well-defined, single-component precatalysts (MePDI)Fe(L2) (where MePDI = 2,6-(2,6-Me2-C6H3N═CMe)2C5H3N; L2 = butadiene or 2(N2)) provided insights into the kinetic and thermodynamic factors contributing to the substrate-controlled regioselectivity for both the homodimerization and cross cycloadditions. Diamagnetic iron diene and paramagnetic iron olefin complexes were identified as catalyst resting states, were characterized by in situ NMR and Mössbauer spectroscopic studies, and were corroborated with DFT calculations. Stoichiometric reactions and computational models provided evidence for a common mechanistic regime where competing steric and orbital-symmetry requirements dictate the regioselectivity of oxidative cyclization. Although distinct chemoselectivity profiles were observed in cross-cycloadditions with the vinylsilane congeners of α-olefins, these products arose from metallacycles with the same connectivity. The silyl substituents ultimately governed the relative rates of β-H elimination and C-C reductive elimination to dictate final product formation.
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Affiliation(s)
| | | | | | - Jordan M. Hoyt
- Department of Chemistry, Princeton University, Princeton, NJ 08544
| | - Carli B. Kovel
- Department of Chemistry, Princeton University, Princeton, NJ 08544
| | - Paul J. Chirik
- Department of Chemistry, Princeton University, Princeton, NJ 08544
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2
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Reiß F, Reiß M, Bresien J, Spannenberg A, Jiao H, Baumann W, Arndt P, Beweries T. 1-Titanacyclobuta-2,3-diene - an elusive four-membered cyclic allene. Chem Sci 2019; 10:5319-5325. [PMID: 31191888 PMCID: PMC6540905 DOI: 10.1039/c9sc01002e] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 04/20/2019] [Indexed: 11/28/2022] Open
Abstract
The synthesis and characterisation of a 1-titanacyclobuta-2,3-diene complex, an organometallic analog of elusive 1,2-cyclobutadiene, is presented.
The synthesis of an unusual 1-metalla-2,3-cyclobutadiene complex [rac-(ebthi)Ti(Me3SiC3SiMe3)] (rac-ebthi = rac-1,2-ethylene-1,1′-bis(η5-tetrahydroindenyl)), a formal metallacyclic analogue of a non-existent four-membered 1,2-cyclobutadiene, is described. By variation of the cyclopentadienyl ligand of the titanocene precursor it was possible to stabilise this highly exotic compound which selectively reacts with ketones and aldehydes to yield enynes by oxygen transfer to titanium. Analysis of the bonding and electronic structure of the metallacycle shows that the complex is best described as an unusual antiferromagnetically coupled biradicaloid system, possessing a formal Ti(iii) centre coordinated with a monoanionic radical ligand.
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Affiliation(s)
- Fabian Reiß
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock , Albert-Einstein-Str. 29a , 18059 Rostock , Germany . ;
| | - Melanie Reiß
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock , Albert-Einstein-Str. 29a , 18059 Rostock , Germany . ;
| | - Jonas Bresien
- Abteilung für Anorganische Chemie , Institut für Chemie , Universität Rostock , Albert-Einstein-Straße 3a , D-18059 Rostock , Germany
| | - Anke Spannenberg
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock , Albert-Einstein-Str. 29a , 18059 Rostock , Germany . ;
| | - Haijun Jiao
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock , Albert-Einstein-Str. 29a , 18059 Rostock , Germany . ;
| | - Wolfgang Baumann
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock , Albert-Einstein-Str. 29a , 18059 Rostock , Germany . ;
| | - Perdita Arndt
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock , Albert-Einstein-Str. 29a , 18059 Rostock , Germany . ;
| | - Torsten Beweries
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock , Albert-Einstein-Str. 29a , 18059 Rostock , Germany . ;
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Rosenthal U. Recent Synthetic and Catalytic Applications of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201801484] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Uwe Rosenthal
- Leibniz Institute for Catalysis at the University of Rostock Albert‐Einstein‐Str. 29A 18059 Rostock Germany
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Bando M, Nakajima K, Song Z, Takahashi T. Metal-dependent regioselective homocoupling of stannyl- and alkyl-substituted alkynes on group 4 elements. Formation of unsymmetrical titanacyclopentadienes and symmetrical zircona-cyclopentadienes. Dalton Trans 2019; 48:13912-13915. [DOI: 10.1039/c9dt02759a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Homocoupling of stannyl- and alkyl-substituted alkynes with Cp2TiBu2 gave unsymmetrical titanacyclopentadienes with >95% regioselectivities, whereas the coupling with Cp2ZrBu2 provided symmetrical zirconacyclopentadienes with >93% selectivities.
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Affiliation(s)
- Masayoshi Bando
- Institute for Catalysis and Graduate School of Life Science
- Hokkaido University
- Sapporo
- Japan
| | - Kiyohiko Nakajima
- Department of Chemistry
- Aichi University of Education
- Igaya, Kariya
- Japan
| | - Zhiyi Song
- Institute for Catalysis and Graduate School of Life Science
- Hokkaido University
- Sapporo
- Japan
| | - Tamotsu Takahashi
- Institute for Catalysis and Graduate School of Life Science
- Hokkaido University
- Sapporo
- Japan
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Guo J, Deng X, Song C, Lu Y, Qu S, Dang Y, Wang ZX. Differences between the elimination of early and late transition metals: DFT mechanistic insights into the titanium-catalyzed synthesis of pyrroles from alkynes and diazenes. Chem Sci 2016; 8:2413-2425. [PMID: 28451348 PMCID: PMC5369339 DOI: 10.1039/c6sc04456e] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 12/22/2016] [Indexed: 01/05/2023] Open
Abstract
Early transition metals (TMs), such as titanium, generally resist undergoing reductive elimination to form C-X bonds due to their weak electronegativity. By analyzing the mechanism of the titanium-catalyzed synthesis of pyrroles from alkynes and diazenes, the present study revealed that titanium is able to promote C-N bond formation via an unconventional elimination pathway, passing through a comparatively stable masked TiII complex (i.e., IM4) rather than pyrrole directly. The formation of IM4 originates from the bilateral donation and back-donation between Ti and the pyrrole ligand. Formally, it could be considered that the two electrons resulting from the unconventional reductive elimination are temporarily buffered by back-donation to a symmetry-allowed unoccupied π-orbital of the pyrrole ring in IM4 rather than becoming a lone pair on a Ti center as adopted in the catalysis of late TMs. Because of its stability, IM4 requires additional oxidation by diazene to liberate pyrrole. The triplet counterpart (IM4T ) of IM4 is more stable than IM4, but the elimination is unlikely to reach IM4T , because the process is spin-forbidden and the spin-orbit coupling is weak. Alternatively, one may consider the forming pyrrole in IM4 as a redox-active ligand, reserving the two electrons resulting from the formal reductive elimination and then releasing the electrons when IM4 is oxidized by diazene. These insights allow us to propose the conditions for early TMs to undergo a similar elimination, whereby the forming product will have symmetry-allowed frontier molecular orbitals to form donation and back-donation bonding with a TM center and a substrate possessing a comparatively strong oxidizing ability to oxidize an IM4-like intermediate for product release. These insights may provide another way of constructing C-X bonds through a similar reductive elimination pathway, using early TM catalysts.
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Affiliation(s)
- Jiandong Guo
- School of Chemistry and Chemical Engineering , University of the Chinese Academy of Sciences , Beijing 100049 , China .
| | - Xi Deng
- School of Chemistry and Chemical Engineering , University of the Chinese Academy of Sciences , Beijing 100049 , China .
| | - Chunyu Song
- School of Chemistry and Chemical Engineering , University of the Chinese Academy of Sciences , Beijing 100049 , China .
| | - Yu Lu
- School of Chemistry and Chemical Engineering , University of the Chinese Academy of Sciences , Beijing 100049 , China .
| | - Shuanglin Qu
- School of Chemistry and Chemical Engineering , University of the Chinese Academy of Sciences , Beijing 100049 , China .
| | - Yanfeng Dang
- School of Chemistry and Chemical Engineering , University of the Chinese Academy of Sciences , Beijing 100049 , China . .,Collaborative Innovation Center of Chemical Science and Engineering , Tianjin 300072 , China
| | - Zhi-Xiang Wang
- School of Chemistry and Chemical Engineering , University of the Chinese Academy of Sciences , Beijing 100049 , China . .,Collaborative Innovation Center of Chemical Science and Engineering , Tianjin 300072 , China
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Tomaschun G, Altenburger K, Reiß F, Becker L, Spannenberg A, Arndt P, Jiao H, Rosenthal U. Group 4 Metallocene Complexes and Cyanopyridines: Coordination or Coupling to Metallacycles. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201501235] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Gabriele Tomaschun
- Leibniz‐Institut für Katalyse e.V. an der Universität Rostock, Albert‐Einstein‐Str. 29a, 18059 Rostock, Germany www.catalysis.de
- Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl‐von‐Ossietzky‐Str. 9–11, 26129 Oldenburg, Germany
| | - Kai Altenburger
- Leibniz‐Institut für Katalyse e.V. an der Universität Rostock, Albert‐Einstein‐Str. 29a, 18059 Rostock, Germany www.catalysis.de
| | - Fabian Reiß
- Leibniz‐Institut für Katalyse e.V. an der Universität Rostock, Albert‐Einstein‐Str. 29a, 18059 Rostock, Germany www.catalysis.de
| | - Lisanne Becker
- Leibniz‐Institut für Katalyse e.V. an der Universität Rostock, Albert‐Einstein‐Str. 29a, 18059 Rostock, Germany www.catalysis.de
| | - Anke Spannenberg
- Leibniz‐Institut für Katalyse e.V. an der Universität Rostock, Albert‐Einstein‐Str. 29a, 18059 Rostock, Germany www.catalysis.de
| | - Perdita Arndt
- Leibniz‐Institut für Katalyse e.V. an der Universität Rostock, Albert‐Einstein‐Str. 29a, 18059 Rostock, Germany www.catalysis.de
| | - Haijun Jiao
- Leibniz‐Institut für Katalyse e.V. an der Universität Rostock, Albert‐Einstein‐Str. 29a, 18059 Rostock, Germany www.catalysis.de
| | - Uwe Rosenthal
- Leibniz‐Institut für Katalyse e.V. an der Universität Rostock, Albert‐Einstein‐Str. 29a, 18059 Rostock, Germany www.catalysis.de
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Altenburger K, Arndt P, Spannenberg A, Rosenthal U. Reactions of Titanocene and Zirconocene Complexes with Bis(tert-butoxy)acetylene - Coordination and C-O Bond Cleavage. Z Anorg Allg Chem 2015. [DOI: 10.1002/zaac.201500529] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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