1
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Li E, Liao X, Guo F, Huang Y, Chen J. N-Heterocyclic Carbene-Catalyzed Asymmetric S N2 Alkylation via Noncovalent Activation. Org Lett 2024; 26:7479-7483. [PMID: 39092835 DOI: 10.1021/acs.orglett.4c02082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
The field of asymmetric catalysis has been developed by exploring noncovalent interactions, particularly within N-heterocyclic carbene-mediated processes. Despite challenges due to the limited number of compatible electrophiles (predominantly π-acceptors), this study introduces the first asymmetric α-alkylation of 3-aryl oxindoles using Csp3 electrophiles. The innovative protocol integrates diverse oxindoles and alkyl, allyl, and propargyl electrophiles, achieving high yields and enantioselectivities. Preliminary mechanistic explorations support a noncovalent catalytic mechanism, enhancing the tool kit for constructing complex chiral molecules with potential applications.
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Affiliation(s)
- En Li
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, Shenzhen 518118, China
| | - Xiaoyun Liao
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, Shenzhen 518118, China
| | - Fangfang Guo
- State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Yong Huang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
| | - Jiean Chen
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, Shenzhen 518118, China
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2
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Rudolf R, Batman D, Mehner N, Walter RRM, Sarkar B. Redox-Active Triazole-Derived Mesoionic Imines with Ferrocenyl Substituents and their Metal Complexes: Directed Hydrogen-Bonding, Unusual C-H Activation and Ion-Pair Formation. Chemistry 2024; 30:e202400730. [PMID: 38634285 DOI: 10.1002/chem.202400730] [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: 02/22/2024] [Revised: 04/17/2024] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
We present herein the synthesis, characterization and complexation of ferrocenyl-substituted MIIs (mesoionic imines) and their metal complexes. In the free MIIs, strong hydrogen bonding interactions are observed between the imine-N and the C-H bonds of the ferrocenyl substituents both in the solid state and in solution. The influence of this hydrogen bonding is so strong that complexation of the MIIs with [IrCp*Cl2]2 yields unique six-membered iridacycles via C-H-activation of the corresponding C-H-site at the Fc-substituent and not the Ph-substituent. This result is in contrast to previous reports in which always a preferential C-H activation at the phenyl substituent is observed in competitive reactions in the presence of ferrocenyl substituents. The corresponding Ir complexes formed after in-situ halide exchange reaction exist in either [Ir-I] contact or as [Ir]+I- solvent separated ion-pairs depending on the solvent polarity. The iodide coordinated and solvent separated ion-pairs display drastically different physical properties. The TEP (Tolman-electronic-parameter) of these ligands was determined and lines up with previously reported MII-ligands. The redox properties were investigated by a combination of electrochemical and spectroelectrochemical methods. We show here how non-covalent interactions can have a drastic influence on the physical and chemical properties of these new class of compounds.
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Affiliation(s)
- Richard Rudolf
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
| | - Derman Batman
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
| | - Niklas Mehner
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
| | - Robert R M Walter
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
| | - Biprajit Sarkar
- Universität Stuttgart, Institut für Anorganische Chemie, Pfaffenwaldring 55, 70569, Stuttgart
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3
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Haug I, Reitz J, Ziane C, Buchmeiser MR, Hansmann MM, Naumann S. Mesoionic N-Heterocyclic Olefins as Initiators for the Lewis Pair Polymerization of Epoxides. Macromol Rapid Commun 2024; 45:e2300716. [PMID: 38497903 DOI: 10.1002/marc.202300716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/14/2024] [Indexed: 03/19/2024]
Abstract
Mesoionic N-heterocyclic olefins (mNHOs) have recently emerged as a novel class of highly nucleophilic and super-basic σ-donor compounds. Making use of these properties in synthetic polymer chemistry, it is shown that a combination of a specific mNHO and a Mg-based Lewis acid (magnesium bis(hexamethyldisilazide), Mg(HMDS)2) delivers poly(propylene oxide) in quantitative yields from the polymerization of the corresponding epoxide (0.1 mol% mNHO loading). The initiation mechanism involves monomer activation by the Lewis acid and direct ring-opening of the monomer by nucleophilic attack of the mNHO, forming a zwitterionic propagating species. Modulation of the mNHO properties is thereby a direct tool to impact initiation efficiency, revealing a sterically unencumbered triazole-derivative as particularly useful. The joint application of mNHOs together with borane-type Lewis acids is also outlined, resulting in high conversions and fast polymerization kinetics. Importantly, while molar mass distributions remain relatively broad, indicating faster propagation than initiation, the overall molar masses are significantly lower than found in the case of regular NHOs, underlining the increased nucleophilicity and ensuing improved initiation efficiency of mNHOs.
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Affiliation(s)
- Iris Haug
- University of Stuttgart, Institute of Polymer Chemistry, 70569, Stuttgart, Germany
| | - Justus Reitz
- TU Dortmund, Faculty for Chemistry and Chemical Biology, 44227, Dortmund, Germany
| | - Célia Ziane
- University of Stuttgart, Institute of Polymer Chemistry, 70569, Stuttgart, Germany
| | - Michael R Buchmeiser
- University of Stuttgart, Institute of Polymer Chemistry, 70569, Stuttgart, Germany
| | - Max M Hansmann
- TU Dortmund, Faculty for Chemistry and Chemical Biology, 44227, Dortmund, Germany
| | - Stefan Naumann
- University of Stuttgart, Institute of Polymer Chemistry, 70569, Stuttgart, Germany
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4
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Ževart T, Pinter B, Lozinšek M, Urankar D, Jansen-van Vuuren RD, Košmrlj J. Towards structurally versatile mesoionic N-heterocyclic olefin ligands and their coordination to palladium, gold, and boron hydride. Dalton Trans 2024; 53:8915-8925. [PMID: 38590282 DOI: 10.1039/d4dt00195h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
We have developed an efficient and versatile approach for the synthesis of a family of 1,2,3-triazole-based mesoionic N-heterocyclic olefin (mNHO) ligands and investigated their coordination to palladium, gold, and boron hydride experimentally and computationally. We reacted mNHOs obtained through deprotonation of the corresponding methylated and ethylated 1,3,4-triaryl-1,2,3-triazolium salts with [Pd(allyl)Cl]2 to give the corresponding [Pd(η3-allyl)Cl(mNHO)] coordination complexes. 13C NMR data revealed the strong σ-donor character of the mNHO ligands, consistent with the calculated bond orders and atom-condensed charges. Furthermore, we also synthesized [AuCl(mNHO)] and a BH3-mNHO adduct by reacting the triazolium salts with AuCl(SMe2) and BH3·THF, respectively. The BH3-mNHO adduct was tested in the reduction of select aldehydes and ketones to alcohols.
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Affiliation(s)
- Tisa Ževart
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI 1000 Ljubljana, Slovenia.
| | - Balazs Pinter
- The University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968, USA
| | - Matic Lozinšek
- Jožef Stefan Institute, Jamova cesta 39, SI 1000 Ljubljana, Slovenia
| | - Damijana Urankar
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI 1000 Ljubljana, Slovenia.
| | - Ross D Jansen-van Vuuren
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI 1000 Ljubljana, Slovenia.
| | - Janez Košmrlj
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI 1000 Ljubljana, Slovenia.
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5
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Sun Q, Eitzinger A, Esken R, Antoni PW, Mayer RJ, Ofial AR, Hansmann MM. Pyridinium-Derived Mesoionic N-Heterocyclic Olefins (py-mNHOs). Angew Chem Int Ed Engl 2024; 63:e202318283. [PMID: 38153170 DOI: 10.1002/anie.202318283] [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: 11/29/2023] [Revised: 12/18/2023] [Accepted: 12/20/2023] [Indexed: 12/29/2023]
Abstract
Mesoionic polarization allows access to electron-rich olefins that have found application as organocatalysts, ligands, or nucleophiles. Herein, we report the synthesis and characterization of a series of 3-methylpyridinium-derived mesoionic olefins (py-mNHOs). We used a DFT-supported design concept, which showed that the introduction of aryl groups in the 1-, 2-, 4-, and 6-positions of the heterocyclic core allowed the kinetic stabilization of the novel mesoionic compounds. Tolman electronic parameters indicate that py-mNHOs are remarkably strong σ-donor ligands toward transition metals and main group Lewis acids. Additionally, they are among the strongest nucleophiles on the Mayr reactivity scale. In reactions of py-mNHOs with electron-poor π-systems, a gradual transition from the formation of zwitterionic adducts via stepwise to concerted 1,3-dipolar cycloadditions was observed experimentally and analyzed by quantum-chemical calculations.
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Affiliation(s)
- Qiu Sun
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Andreas Eitzinger
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Robin Esken
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Patrick W Antoni
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Robert J Mayer
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS), CNRS UMR 7006, Université de Strasbourg, 8 Allée Gaspard Monge, 67000, Strasbourg, France
| | - Armin R Ofial
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Max M Hansmann
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
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6
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Rajendran NM, Lu Q, Bouffard J. A Facile Preparation of N-Heterocyclic Olefins: Ring-Opening Polymerization of β-Butyrolactone and Frustrated Lewis Pair Reactivity. Chemistry 2024; 30:e202303358. [PMID: 38109087 DOI: 10.1002/chem.202303358] [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: 10/12/2023] [Indexed: 12/19/2023]
Abstract
A direct synthesis of N-heterocyclic olefins (NHOs) and their mesoionic congeners (mNHOs) from N-heterocyclic carbenes and N-aziridinylimines is reported. The reaction provided diverse functionalized (m)NHOs and π-extended analogues. The prepared NHOs initiated the ring-opening polymerization of β-butyrolactone, and insertion of aldehyde and nitrile into an NHO-B(C6 F5 )3 adduct was demonstrated.
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Affiliation(s)
| | - Qi Lu
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul, 03760, Korea
| | - Jean Bouffard
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul, 03760, Korea
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7
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Wang S, Yang J, Zeng H, Zhou Y, Wang F, Feng X, Dong S. Asymmetric Formal Coupling of β-Ketoesters with Quinones Promoted by a Chiral Bifunctional N-Heterocyclic Olefin. Org Lett 2023; 25:7247-7251. [PMID: 37750718 DOI: 10.1021/acs.orglett.3c02885] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
A highly enantioselective formal coupling of β-ketoesters with quinones was accomplished by a chiral bifunctional N-heterocyclic olefin organocatalyst. With as low as 1 mol % catalyst loading, a number of enantioenriched quinone derivatives were afforded in good yields with high enantioselectivities and regioselectivities (up to 96% yield, 98% ee, and 19:1 rr). Gram-scale synthesis and the high inhibitory effect of several products on the viability of cancer cells demonstrate the potential utility of the current method.
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Affiliation(s)
- Sijing Wang
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Jia Yang
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Hongkun Zeng
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Yuqiao Zhou
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Fei Wang
- Center for Natural Products Research, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610064, China
| | - Xiaoming Feng
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Shunxi Dong
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
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8
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Eitzinger A, Reitz J, Antoni PW, Mayr H, Ofial AR, Hansmann MM. Pushing the Upper Limit of Nucleophilicity Scales by Mesoionic N-Heterocyclic Olefins. Angew Chem Int Ed Engl 2023; 62:e202309790. [PMID: 37540606 DOI: 10.1002/anie.202309790] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/03/2023] [Accepted: 08/04/2023] [Indexed: 08/06/2023]
Abstract
A series of mesoionic, 1,2,3-triazole-derived N-heterocyclic olefins (mNHOs), which have an extraordinarily electron-rich exocyclic CC-double bond, was synthesized and spectroscopically characterized, in selected cases by X-ray crystallography. The kinetics of their reactions with arylidene malonates, ArCH=C(CO2 Et)2 , which gave zwitterionic adducts, were investigated photometrically in THF at 20 °C. The resulting second-order rate constants k2 (20 °C) correlate linearly with the reported electrophilicity parameters E of the arylidene malonates (reference electrophiles), thus providing the nucleophile-specific N and sN parameters of the mNHOs according to the correlation lg k2 (20 °C)=sN (N+E). With 21
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Affiliation(s)
- Andreas Eitzinger
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Justus Reitz
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Patrick W Antoni
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
| | - Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Armin R Ofial
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13 (Haus F), 81377, München, Germany
| | - Max M Hansmann
- Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227, Dortmund, Germany
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9
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Hansmann MM. Diazoalkenes: From an Elusive Intermediate to a Stable Substance Class in Organic Chemistry. Angew Chem Int Ed Engl 2023; 62:e202304574. [PMID: 37095063 DOI: 10.1002/anie.202304574] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/22/2023] [Accepted: 04/24/2023] [Indexed: 04/26/2023]
Abstract
Over decades diazoalkenes (R2 C=C=N2 ) were postulated as reactive intermediates in organic chemistry even though their direct spectroscopic detection proved very challenging. In the 1970/80ies several groups probed their existence mainly indirectly by trapping experiments or directly by matrix-isolation studies. In 2021, our group and the Severin group reported independently the synthesis and characterization of the first room-temperature stable diazoalkenes, which initiated a rapidly expanding research field. Up to now four different classes of N-heterocyclic substituted room-temperature stable diazoalkenes have been reported. Their properties and unique reactivity, such as N2 /CO exchange or utilization as vinylidene precursors in organic and transition metal chemistry are presented. This review summarizes the early discoveries of diazoalkenes from their initial postulation as transient, elusive species up to the recent findings of the room-temperature stable derivatives.
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Affiliation(s)
- Max M Hansmann
- Technische Universität Dortmund, Fakultät für Chemie und Chemische Biologie, Otto-Hahn-Str. 6, Dortmund, Germany
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10
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G M, Sharma D, Dandela R, Dhayalan V. Synthetic Strategies of N-Heterocyclic Olefin (NHOs) and Their Recent Application of Organocatalytic Reactions and Beyond. Chemistry 2023:e202302106. [PMID: 37605950 DOI: 10.1002/chem.202302106] [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: 07/03/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 08/23/2023]
Abstract
N-heterocyclic olefin (NHO) derivatives have an electron-rich as well as highly polarized carabon-carbon (C=C) double bond because of the electron-donating nature of nitrogen and sulphur atoms. While NHOs have been developing as novel organocatalysts and ligands for transition-metal complexes in various organic compound syntheses, different research groups are currently interested in preparing imidazole and triazolium-based chiral NHO catalysts. Some of them have been used for enantioselective organic transformations, but were still elusive. N-heterocyclic olefins, the alkylidene derivatives of N-heterocyclic carbenes (NHC), have shown promising results as effective promoters for numerous organic syntheses such as asymmetric catalysis, hydroborylation, hydrosilylation, reduction, CO2 sequestration, alkylation, cycloaddition, polymerization and the ring-opening reaction of aziridine and epoxides, esterification, C-F bond functionalization, amine coupling, trifluoromethyl thiolation, amination etc. NHOs catalysts with suitable structures can serve as a novel class of Lewis/Bronsted bases with strong basicity and high nucleophilicity properties.These facts strongly suggest their enormous chemical potential as sustainable catalysts for a wide variety of reactions in synthetic chemistry. The synthesis of NHOs and their properties are briefly reviewed in this article, along with a summary of the imidazole and triazole core of NHOs' most recent catalytic uses.
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Affiliation(s)
- Mahantesh G
- Department of Chemistry, National Institute of Technology Puducherry, Karaikal, 609609, Union Territory Puducherry, India
| | - Deepika Sharma
- Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, Indian oil Odisha Campus, IIT, Kharagpur extension Centre Mouza Samantpuri, Bhubaneswar, 751013, Odisha, India
| | - Rambabu Dandela
- Department of Industrial and Engineering Chemistry, Institute of Chemical Technology, Indian oil Odisha Campus, IIT, Kharagpur extension Centre Mouza Samantpuri, Bhubaneswar, 751013, Odisha, India
| | - Vasudevan Dhayalan
- Department of Chemistry, National Institute of Technology Puducherry, Karaikal, 609609, Union Territory Puducherry, India
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11
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Kooij B, Varava P, Fadaei-Tirani F, Scopelliti R, Pantazis DA, Van Trieste GP, Powers DC, Severin K. Copper Complexes with Diazoolefin Ligands and their Photochemical Conversion into Alkenylidene Complexes. Angew Chem Int Ed Engl 2023; 62:e202214899. [PMID: 36445783 DOI: 10.1002/anie.202214899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 11/30/2022]
Abstract
Homometallic copper complexes with alkenylidene ligands are discussed as intermediates in catalysis but the isolation of such complexes has remained elusive. Herein, we report the structural characterization of copper complexes with bridging and terminal alkenylidene ligands. The compounds were obtained by irradiation of CuI complexes with N-heterocyclic diazoolefin ligands. The complex with a terminal alkenylidene ligand required isolation in a crystalline matrix, and its structural characterization was enabled by in crystallo photolysis at low temperature.
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Affiliation(s)
- Bastiaan Kooij
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Paul Varava
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Farzaneh Fadaei-Tirani
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Rosario Scopelliti
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | | | | | - David C Powers
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Kay Severin
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
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12
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Wang S, Zhang C, Li D, Zhou Y, Su Z, Feng X, Dong S. New chiral N-heterocyclic olefin bifunctional organocatalysis in α-functionalization of β-ketoesters. Sci China Chem 2022. [DOI: 10.1007/s11426-022-1458-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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