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Marchenko A, Koidan G, Hurieva A, Shvydenko K, Rozhenko AB, Rusanov EB, Kyrylchuk AA, Kostyuk A. Latent Nucleophilic Carbenes. J Org Chem 2021; 87:373-385. [PMID: 34898214 DOI: 10.1021/acs.joc.1c02397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using DFT and ab initio calculations, we demonstrate that noncyclic formamidines can undergo thermal rearrangement into their isomeric aminocarbenes under rather mild conditions. We synthesized the silylformamidine, for which the lowest activation energy in this process was predicted. Experimental studies proved it to serve as a very reactive nucleophilic carbene. The reactions with acetylenes, benzenes, and trifluoromethane proceeded via insertion into sp, sp2, and sp3 CH bonds. The carbene also reacted with the functional groups, such as CHO, COR, and CN at double or triple bonds, displaying high mobility of the trimethylsilyl group. The obtained silylformamidine can be considered as a latent nucleophilic carbene. It can be prepared in bulk quantities, stored, and used when the need arises. Calculation results predict similar behavior for some other silylated formamidines and related compounds.
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Affiliation(s)
- Anatoliy Marchenko
- Department of Organophosphorus Chemistry, Institute of Organic Chemistry, Murmanska 5, Kyiv 02660, Ukraine
| | - Georgyi Koidan
- Department of Organophosphorus Chemistry, Institute of Organic Chemistry, Murmanska 5, Kyiv 02660, Ukraine
| | - Anastasiya Hurieva
- Department of Organophosphorus Chemistry, Institute of Organic Chemistry, Murmanska 5, Kyiv 02660, Ukraine
| | - Kostiantyn Shvydenko
- Department of Organophosphorus Chemistry, Institute of Organic Chemistry, Murmanska 5, Kyiv 02660, Ukraine
| | - Alexander B Rozhenko
- Igor Sikorsky Kyiv Polytechnic Institute, National Technical University of Ukraine, Prosp. Peremohy 37, Kyiv 03056, Ukraine.,Department of Physicochemical Investigations, Institute of Organic Chemistry, Murmanska 5, Kyiv 02660, Ukraine
| | - Eduard B Rusanov
- Department of Physicochemical Investigations, Institute of Organic Chemistry, Murmanska 5, Kyiv 02660, Ukraine
| | - Andrii A Kyrylchuk
- Department of Physicochemical Investigations, Institute of Organic Chemistry, Murmanska 5, Kyiv 02660, Ukraine
| | - Aleksandr Kostyuk
- Department of Organophosphorus Chemistry, Institute of Organic Chemistry, Murmanska 5, Kyiv 02660, Ukraine
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Moerdyk JP, Schilter D, Bielawski CW. N,N'-Diamidocarbenes: Isolable Divalent Carbons with Bona Fide Carbene Reactivity. Acc Chem Res 2016; 49:1458-68. [PMID: 27409520 DOI: 10.1021/acs.accounts.6b00080] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Since the first reported isolation of a carbene just over a quarter century ago, the study of such compounds-including stable derivatives-has flourished. Indeed, N-heterocyclic carbenes (NHCs), of which imidazolylidenes and their derivatives are the most pervasive subclass, feature prominently in organocatalysis, as ligands for transition metal catalysts, and as stabilizers of reactive species. However, imidazolylidenes (and many other NHCs) typically lack the reactivity characteristic of electrophilic carbenes, including insertion into unactivated C-H bonds, participation in [2 + 1] cycloadditions, and reaction with carbon monoxide. This has led to debates over whether NHCs are truly carbenic in nature or perhaps better regarded as ylides. The fundamental and synthetic utility of transformations that involve electrophilic carbenes has motivated our group and others to expand the reactivity of NHCs and other stable carbenes to encompass electrophilic carbene chemistry. These efforts have led to the development of the diamidocarbenes (DACs), a stable and unique subset of the NHCs that feature carbonyl groups inserted into the N-heterocyclic scaffold. To date, crystalline five-, six-, and seven-membered DACs have been prepared and studied. Unlike imidazolylidenes, which are often designated as prototypical NHCs, the DACs exhibit a reactivity profile similar to that of bona fide carbenes, reactive species that are less "tamed" by heteroatom π conjugation. The DACs engage in [2 + 1] cycloadditions with electron-rich or -poor alkenes, aldehydes, alkynes, and nitriles, and doing so in a reversible manner in some cases. They also react with isonitriles, reversibly couple to CO, and mediate the dehydrogenation of hydrocarbons. Such rich chemistry may be rationalized in terms of their ambiphilicity: DACs are nucleophilic, as required for some of the reactions above, yet also have electrophilic character, as evidenced by their insertions into unactivated N-H and C-H bonds, including nonacidic derivatives. As will become clear, such reactivity is unique among isolable carbenes. DAC chemistry is expected to find applications in synthesis, dynamic covalent chemistry, and catalysis. For example, the hydrolysis of DAC-derived diamidocyclopropanes and -propenes affords carboxylic acids and cyclopropenones, respectively. These new hydrocarboxylation and carbonylation methodologies are significant in that they represent alternatives to processes that typically involve precious metals and gaseous carbon monoxide. Future efforts in this area may involve modifications that transform the stoichiometric conversions facilitated by DACs into catalytic variants. In this context, the reversible binding of CO to DACs is an indication that the latter may serve as a blueprint for the development of more electrophilic, stable carbenes with the capacity to activate other challenging small molecules.
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Affiliation(s)
- Jonathan P. Moerdyk
- Department
of Chemistry, Seton Hill University, Greensburg, Pennsylvania 15601, United States
| | - David Schilter
- Center
for Multidimensional Carbon Materials (CMCM), Institute for Basic
Science (IBS), Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Christopher W. Bielawski
- Center
for Multidimensional Carbon Materials (CMCM), Institute for Basic
Science (IBS), Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Department
of Chemistry and Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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Yatham VR, Harnying W, Kootz D, Neudörfl JM, Schlörer NE, Berkessel A. 1,4-Bis-Dipp/Mes-1,2,4-Triazolylidenes: Carbene Catalysts That Efficiently Overcome Steric Hindrance in the Redox Esterification of α- and β-Substituted α,β-Enals. J Am Chem Soc 2016; 138:2670-7. [PMID: 26797403 DOI: 10.1021/jacs.5b11796] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
As reported by Scheidt and Bode in 2005, sterically nonencumbered α,β-enals are readily converted to saturated esters in the presence of alcohols and N-heterocyclic carbene catalysts, e.g., benzimidazolylidenes or triazolylidenes. However, substituents at the α- or β-position of the α,β-enal substrate are typically not tolerated, thus severely limiting the substrate spectrum. On the basis of our earlier mechanistic studies, a set of N-Mes- or N-Dipp-substituted 1,2,4-triazolium salts were synthesized and evaluated as (pre)catalysts in the redox esterification of various α- or β-substituted enals. In particular the 1,4-bis-Mes/Dipp-1,2,4-triazolylidenes overcome the above limitations and efficiently catalyze the redox esterification of a whole series of α/β-substituted enals hitherto not amenable to NHC-catalyzed transformations. The synthetic value of 1,4-bis-Mes/Dipp-1,2,4-triazolylidenes is further demonstrated by the one-step bicyclization of 10-oxocitral to (racemic) nepetalactone in diastereomerically pure form.
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Affiliation(s)
- Veera Reddy Yatham
- Department of Chemistry (Organic Chemistry), University of Cologne , Greinstrasse 4, 50939 Cologne, Germany
| | - Wacharee Harnying
- Department of Chemistry (Organic Chemistry), University of Cologne , Greinstrasse 4, 50939 Cologne, Germany
| | - Darius Kootz
- Department of Chemistry (Organic Chemistry), University of Cologne , Greinstrasse 4, 50939 Cologne, Germany
| | - Jörg-M Neudörfl
- Department of Chemistry (Organic Chemistry), University of Cologne , Greinstrasse 4, 50939 Cologne, Germany
| | - Nils E Schlörer
- Department of Chemistry (Organic Chemistry), University of Cologne , Greinstrasse 4, 50939 Cologne, Germany
| | - Albrecht Berkessel
- Department of Chemistry (Organic Chemistry), University of Cologne , Greinstrasse 4, 50939 Cologne, Germany
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Di Marco L, Hans M, Delaude L, Monbaliu JCM. Continuous-Flow N-Heterocyclic Carbene Generation and Organocatalysis. Chemistry 2016; 22:4508-14. [DOI: 10.1002/chem.201505135] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Lorenzo Di Marco
- Center for Integrated Technology and Organic Synthesis; Department of Chemistry; University of Liège; 4000 Liège Belgium
| | - Morgan Hans
- Center for Integrated Technology and Organic Synthesis; Department of Chemistry; University of Liège; 4000 Liège Belgium
| | - Lionel Delaude
- Laboratory of Organometallic Chemistry and Homogeneous Catalysis; Department of Chemistry; University of Liège; 4000 Liège Belgium
| | - Jean-Christophe M. Monbaliu
- Center for Integrated Technology and Organic Synthesis; Department of Chemistry; University of Liège; 4000 Liège Belgium
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Schmidt A, Wiechmann S, Otto CF. N-Heterocyclic Carbenes. ADVANCES IN HETEROCYCLIC CHEMISTRY 2016. [DOI: 10.1016/bs.aihch.2016.02.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Lee YG, Kang S, Moerdyk JP, Bielawski CW. Poly(2-imino-4-oxazolidinone)s via the Condensation of Diamidocarbenes with Bis(isocyanate)s. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b01930] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Young-Gi Lee
- Department of Electronic Materials, Samsung SDI Company Ltd., Suwon 443-803, Republic of Korea
- Department of Chemistry, University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712, United States
- Seton Hill University, One Seton Hill Drive, Greensburg, Pennsylvania 15601, United States
- Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan 689-798, Republic of Korea
- Department of Chemistry and Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
| | - Songsu Kang
- Department of Electronic Materials, Samsung SDI Company Ltd., Suwon 443-803, Republic of Korea
- Department of Chemistry, University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712, United States
- Seton Hill University, One Seton Hill Drive, Greensburg, Pennsylvania 15601, United States
- Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan 689-798, Republic of Korea
- Department of Chemistry and Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
| | - Jonathan P. Moerdyk
- Department of Electronic Materials, Samsung SDI Company Ltd., Suwon 443-803, Republic of Korea
- Department of Chemistry, University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712, United States
- Seton Hill University, One Seton Hill Drive, Greensburg, Pennsylvania 15601, United States
- Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan 689-798, Republic of Korea
- Department of Chemistry and Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
| | - Christopher W. Bielawski
- Department of Electronic Materials, Samsung SDI Company Ltd., Suwon 443-803, Republic of Korea
- Department of Chemistry, University of Texas at Austin, 1 University Station, A5300, Austin, Texas 78712, United States
- Seton Hill University, One Seton Hill Drive, Greensburg, Pennsylvania 15601, United States
- Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan 689-798, Republic of Korea
- Department of Chemistry and Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
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Yatham VR, Neudörfl JM, Schlörer NE, Berkessel A. Carbene catalyzed umpolung of α,β-enals: a reactivity study of diamino dienols vs. azolium enolates, and the characterization of advanced reaction intermediates. Chem Sci 2015; 6:3706-3711. [PMID: 28706717 PMCID: PMC5496186 DOI: 10.1039/c5sc01027f] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 04/30/2015] [Indexed: 11/21/2022] Open
Abstract
Since their discovery by Bode and Glorius in 2004, N-heterocyclic carbene catalyzed conjugate umpolung reactions of α,β-enals have been postulated to involve the formation of diamino dienols ("homoenolates") and/or azolium enolates ("enolates"), typically followed by addition to electrophiles, e.g. Michael-acceptors. In this article, we provide evidence, for the first time, for the postulated individual and specific reactivity patterns of diamino dienols (γ-C-C-bond formation) vs. azolium enolates (β-C-C-bond formation). Our study is based on the pre-formation of well defined diamino dienols and azolium enolates, and the in situ NMR monitoring of their reactivities towards enone electrophiles. Additionally, reaction intermediates were isolated and characterized, inter alia by X-ray crystallography.
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Affiliation(s)
- Veera Reddy Yatham
- Department of Chemistry , Cologne University , Greinstrasse 4 , 50939 Cologne , Germany . ; ; Tel: +49-221-470-3283
| | - Jörg-M Neudörfl
- Department of Chemistry , Cologne University , Greinstrasse 4 , 50939 Cologne , Germany . ; ; Tel: +49-221-470-3283
| | - Nils E Schlörer
- Department of Chemistry , Cologne University , Greinstrasse 4 , 50939 Cologne , Germany . ; ; Tel: +49-221-470-3283
| | - Albrecht Berkessel
- Department of Chemistry , Cologne University , Greinstrasse 4 , 50939 Cologne , Germany . ; ; Tel: +49-221-470-3283
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Collins LR, Lowe JP, Mahon MF, Poulten RC, Whittlesey MK. Copper diamidocarbene complexes: characterization of monomeric to tetrameric species. Inorg Chem 2014; 53:2699-707. [PMID: 24512071 PMCID: PMC3989936 DOI: 10.1021/ic4031014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Indexed: 11/28/2022]
Abstract
Treatment of CuCl with 1 equiv of the in situ prepared N-mesityl-substituted diamidocarbene 6-MesDAC produced a mixture of the dimeric and trimeric copper complexes [(6-MesDAC)CuCl]2 (1) and [(6-MesDAC)2(CuCl)3] (2). Combining CuCl with isolated, free 6-MesDAC in 1:1 and 3:2 ratios gave just 1 and 2, respectively, while increasing the ratio to >5:1 allowed the isolation of small amounts of the tetrameric copper complex [(6-MesDAC)2(CuCl)4] (3). Efforts to bring about metathesis reactions of 1 with MO(t)Bu (M = Li, Na, K) proved successful only for M = Li to afford the spectroscopically characterized ate product [(6-MesDAC)CuCl·LiO(t)Bu·2THF] (5). Attempts to crystallize this species instead gave a 1:1 mixture of 1 and the monomer [(6-MesDAC)CuCl] (6). The X-ray structures of 1-3 and 1 + 6, along with the cation [Cu(6-MesDAC)2](+) (4), have been determined.
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Affiliation(s)
- Lee R. Collins
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - John P. Lowe
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Mary F. Mahon
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Rebecca C. Poulten
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
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Mahatthananchai J, Bode JW. On the mechanism of N-heterocyclic carbene-catalyzed reactions involving acyl azoliums. Acc Chem Res 2014; 47:696-707. [PMID: 24410291 DOI: 10.1021/ar400239v] [Citation(s) in RCA: 563] [Impact Index Per Article: 56.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Catalytic reactions promoted by N-heterocyclic carbenes (NHCs) have exploded in popularity since 2004 when several reports described new fundamental reactions that extended beyond the long-studied generation of acyl anion equivalents. These new NHC-catalyzed reactions allow chemists to generate unique reactive species from otherwise inert starting materials, all under simple, mild reaction conditions and with exceptional selectivities. In analogy to transition metal catalysis, the use of NHCs has introduced a new set of elementary steps that operate via discrete reactive species, including acyl anion, homoenolate, and enolate equivalents, usually generated by oxidation state reorganization ("redox neutral" reactions). Nearly all NHC-catalyzed reactions offer operationally simple reactions, proceed at room temperature without the need for stringent exclusion of air, and do not generate reaction byproducts. Variation of the catalyst or reaction conditions can profoundly influence reaction outcomes, and researchers can tune the desired selectivities through careful choice of NHC precursor and base. The catalytically generated homoenolate and enolate equivalents are nucleophilic species. In contrast, the catalytically generated acyl azolium and α,β-unsaturated acyl azoliums are electrophilic cationic species with unique and unprecedented chemistry. For example, when generated catalytically, these species transformed an α-functionalized aldehyde to an ester under redox neutral conditions without coupling reagents or waste. In addition to providing new approaches to catalytic esterifications, acyl azoliums offer unique reactivities that chemists can exploit for selective reactions. This Account focuses on the discovery and mechanistic investigation of the catalytic generation of acyl azoliums and α,β-unsaturated acyl azoliums. These chemical species are fascinating, and their catalytic generation is an important development. Studies of their unusual chemistry, however, date back to the intense investigation of thiamine-dependent enzymatic processes in the 1960s. Acyl azoliums are remarkably reactive in acylation chemistry and are unusually chemoselective. These two properties have led to a new wave of reactions such as redox esterification reaction (1) and the catalytic kinetic resolution of challenging substrates (i.e., 3). Our group and others have also developed methods to generate and exploit α,β-unsaturated acyl azoliums, which have facilitated new C-C bond-forming annulations, including a catalytic, enantioselective variant of the Claisen rearrangement (2). From essentially one class of catalysts, the N-mesityl derived triazolium salts, researchers can easily prepare highly enantioenriched dihydropyranones and dihydropyridinones. Although this field is now one of the most explored areas of enantioselective C-C bond forming reactions, many mechanistic details remained unsolved and in dispute. In this Account, we address the mechanistic inquiries about the characterization of the unsaturated acyl triazolium species and its kinetic profile under catalytically relevant conditions. We also provide explanations for the requirement and effect of the N-mesityl group in NHC catalysis based on detailed experimental data within given specific reactions or conditions. We hope that our studies provide a roadmap for catalyst design/selection and new reaction discovery based on a fundamental understanding of the mechanistic course of NHC reactions.
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Affiliation(s)
- Jessada Mahatthananchai
- Laboratorium für Organische Chemie, ETH−Zürich, Wolfgang Pauli Strasse 10, 8093 Zürich, Switzerland
| | - Jeffrey W. Bode
- Laboratorium für Organische Chemie, ETH−Zürich, Wolfgang Pauli Strasse 10, 8093 Zürich, Switzerland
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Allen AD, Tidwell TT. Structure and Mechanism in Ketene Chemistry. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2014. [DOI: 10.1016/b978-0-12-800256-8.00004-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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A theoretical study on the hydrogen adducts of diamidocarbenes and diaminocarbenes. J Mol Model 2013; 19:5523-32. [PMID: 24248914 DOI: 10.1007/s00894-013-2052-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 10/28/2013] [Indexed: 01/18/2023]
Abstract
The hybrid-meta GGA DFT functional M06-2X was used to examine the potential of N,N'-diamidocarbenes for use as hydrogen storage materials. We previously discovered that borylene, which is isoelectronic with an Arduengo-type carbene, was a suitable candidate for a hydrogen storage material. We compared the capabilities of N,N'-diamidocarbenes and N-heterocyclic carbenes as hydrogen storage materials. The results indicate that diamidocarbenes are not suitable hydrogen storage materials because the removal of H₂ is more endothermic for diamidocarbenes than for diaminocarbenes.
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César V, Labat S, Miqueu K, Sotiropoulos JM, Brousses R, Lugan N, Lavigne G. The ambivalent chemistry of a free anionic N-heterocyclic carbene decorated with a malonate backbone: the plus of a negative charge. Chemistry 2013; 19:17113-24. [PMID: 24307368 DOI: 10.1002/chem.201303184] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Indexed: 11/08/2022]
Abstract
The anionic heterocycle "[maloNHC](-)", ([1](-)), is the archetype of a growing family of N-heterocyclic carbenes incorporating an anionic backbone; here, a malonate group. A comprehensive experimental exploration of its chemistry as a free entity (in the form of its lithium salt [1]·Li) is presented, and rationalized using DFT calculations at the B3LYP/6-31+G** level of theory. For the sake of comparison, similar computations were performed on other representative carbene types. Reactions of [1]·Li with a broad series of electrophilic reagents were used to ascertain its intrinsic nature as a nucleophilic carbene. Unexpectedly, [1]·Li was also seen to react with the nucleophilic tert-butylisocyanide, to give an anionic ketenimine, which could be subsequently derivatized, either into an imine by protonation of the ketenimine moiety, or into a neutral ketenimine by alkylation of the intracyclic malonate moiety. Further experiments on the electrophilic behavior of [1]·Li revealed its unexpected reactivity toward p-chlorobenzaldehyde, resulting in a formal C-H activation and the first structurally characterized keto-tautomer of the Breslow intermediate. Finally, [1]·Li remarkably activates polar E-H bonds, including N-H bonds from ammonia and amines, Si-H bonds, and B-H bonds. Importantly, DFT calculations indicate the importance of counterion effects. In particular, the key to the observed reactivity appears to be a modulation of energy levels associated with a dynamic variability of the Li-O distance between the remote malonate group and the counterion.
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Affiliation(s)
- Vincent César
- CNRS, LCC (laboratoire de chimie de coordination), 205 route de Narbonne, BP44099, 31077 Toulouse Cedex 4 (France); Université de Toulouse, UPS, INPT, 31077 Toulouse (France).
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Chen M, Moerdyk JP, Blake GA, Bielawski CW, Lee JK. Assessing the Proton Affinities of N,N′-Diamidocarbenes. J Org Chem 2013; 78:10452-8. [DOI: 10.1021/jo401902c] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Mu Chen
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
| | - Jonathan P. Moerdyk
- Department
of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712,
United States
| | - Garrett A. Blake
- Department
of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712,
United States
| | - Christopher W. Bielawski
- Department
of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712,
United States
| | - Jeehiun K. Lee
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, United States
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Berkessel A, Yatham VR, Elfert S, Neudörfl JM. Charakterisierung der Schlüsselintermediate von carbenkatalysierten Umpolungen durch Kristallstrukturanalyse/NMR-Spektroskopie: Breslow-Intermediate, Homoenolate und Azoliumenolate. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201303107] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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16
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Berkessel A, Yatham VR, Elfert S, Neudörfl JM. Characterization of the Key Intermediates of Carbene-Catalyzed Umpolung by NMR Spectroscopy and X-Ray Diffraction: Breslow Intermediates, Homoenolates, and Azolium Enolates. Angew Chem Int Ed Engl 2013; 52:11158-62. [DOI: 10.1002/anie.201303107] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Indexed: 12/24/2022]
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Lai CH. A comparison of diamino- and diamidocarbenes toward dimerization. J Mol Model 2013; 19:4387-94. [PMID: 23918224 DOI: 10.1007/s00894-013-1957-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 07/22/2013] [Indexed: 11/24/2022]
Abstract
In this study, we compare the dimerization of N,N'-diamidocarbene with that of N-heterocyclic carbene (NHC). Less interaction occurred between the filled lone pair of nitrogen and the unfilled lone pair of the carbenic center for a N,N'-diamdiocarbene than did in a saturated NHC because of the resonance between the lone pair of nitrogen and a carbonyl group. Therefore, a N,N'-diamidocarbene exhibits less singlet-triplet splitting. The less singlet-triplet splitting in a heterocyclic carbene containing nitrogen, the more exothermic the dimerization, which is consistent with the conclusion of Thiel et al. (Chem Phys Lett 217:11-16, 1994).
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Affiliation(s)
- Chin-Hung Lai
- School of Applied Chemistry and Department of Medical Education, Chung Shan Medical University, 402, Taichung, Taiwan,
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Martin CD, Soleilhavoup M, Bertrand G. Carbene-Stabilized Main Group Radicals and Radical Ions. Chem Sci 2013; 4:3020-3030. [PMID: 23878717 PMCID: PMC3714118 DOI: 10.1039/c3sc51174j] [Citation(s) in RCA: 407] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Shortly after their discovery at the end of the 80s, stable singlet carbenes have been recognized as excellent ligands for transition metal based catalysts, and as organo-catalysts in their own right. At the end of the 2000s, it has been shown that they can coordinate main group elements in their zero oxidation state, and even activate small molecules. This review covers examples in the literature dealing with the most recent application of stable singlet carbenes, namely their use to stabilize radicals and radical ions that are otherwise unstable.
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Affiliation(s)
- Caleb D. Martin
- Joint CNRS-UCSD Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358
| | - Michele Soleilhavoup
- Joint CNRS-UCSD Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358
| | - Guy Bertrand
- Joint CNRS-UCSD Research Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358
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Maji B, Mayr H. Structures and Ambident Reactivities of Azolium Enolates. Angew Chem Int Ed Engl 2013; 52:11163-7. [DOI: 10.1002/anie.201303524] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 05/15/2013] [Indexed: 12/27/2022]
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Synthesis, structure, and thermochemistry of adduct formation between N-heterocyclic carbenes and isocyanates or mesitylnitrile oxide. Struct Chem 2013. [DOI: 10.1007/s11224-013-0305-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Affiliation(s)
- Annette D. Allen
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Thomas T. Tidwell
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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Lai CH. Computational comparison of the kinetic stabilities of diamino- and diamidocarbenes in the 1,2-H shift reaction. J Mol Model 2013; 19:2935-44. [PMID: 23559095 DOI: 10.1007/s00894-013-1818-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 03/05/2013] [Indexed: 10/27/2022]
Abstract
In this study, we performed several DFT, MP2, and BD(T) calculations on the 1,2-H shift reactions of two diaminocarbenes (1, 2) and a diamidocarbene (3) using the Gaussian 09 program. In Gaussian 09, the BD(T) method keyword requests a Brueckner doubles calculation including a perturbative triples contribution. Although N-heterocyclic carbenes (NHC) are typically known for their exceptional σ-donor abilities, recent studies have indicated that π-interactions also play a role in the bonding between NHCs and transition metals or BX3 (X = H, OH, NH2, CH3, CN, NC, F, Cl, and Br) (Nemcsok et al. Organomet 23:3640-3646, 2004, Esrafili. J Mol Model 18:2003-2011, 2012). In order to study the importance of π-interactions between carbenes and transition metals, Hobbs and co-workers (Hobbs et al. New J Chem 34:1295-1308, 2010) focused on the synthesis of NHCs with reduced-energy lowest unoccupied molecular orbitals. By introducing an oxalamide moiety into the heterocyclic backbone, they found the resulting carbene possessed higher electrophilicity than usual NHCs. According to our results, the N,N'-diamidocarbene should be more stable than the diaminocarbenes with respect to the 1,2-H shift reaction.
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Affiliation(s)
- Chin-Hung Lai
- School of Applied Chemistry and Department of Medical Education, Chung Shan Medical University, 402, Taichung, Taiwan.
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Martin CD, Weinstein CM, Moore CE, Rheingold AL, Bertrand G. Exploring the reactivity of white phosphorus with electrophilic carbenes: synthesis of a P4 cage and P8 clusters. Chem Commun (Camb) 2013; 49:4486-8. [DOI: 10.1039/c3cc42041h] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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