- Application of Quantitative 1H and 19F NMR to Organometallics
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Purity assessment of organometallics is particularly important for catalytic applications. While quantitative NMR is a well-known method in pharmaceutic chemistry, the present work illustrates its usefulness for the determination of the ligands and organometallics purities using proton and fluorine NMR. This method is fast, straightforward and provides accuracy results.
- Akhdar, Ayman,Andanson, Jean-Michel,Faure, Sophie,Gautier, Arnaud,Tra?kia, Mounir
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- Mechanism studies of oxidation and hydrolysis of Cu(I)–NHC and Ag–NHC in solution under air
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The decomposition of copper(I)–NHC and silver-NHC complexes in solution under air was studied. The Cu(I)–NHCs were oxidized into urea derivatives and hydrolysed into imidazoliums or benzimidazoliums. The decomposition of Ag–NHC with a saturated backbone led to ring-opening product, while the Ag–NHC with an unsaturated backbone led to imidazolium and Ag-bisNHC complex. The effects of steric property, hydrophilicity, and binding energy of NHC to O2 and H2O on the decomposition of Cu(I)–NHC were studied using theoretical calculations. Steric hindrance played an important role on the stability of Cu(I)–NHC. Pathways for the decomposition of Cu(I)–NHC and Ag–NHC were proposed.
- Li, Dazhi,Ollevier, Thierry
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supporting information
(2019/11/29)
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- Synthesis of Imidazolidinone, Imidazolone, and Benzimidazolone Derivatives through Oxidation Using Copper and Air
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A new synthetic method of urea derivatives using copper and air was developed. These mild conditions provided moderate to very good yields for 15 examples (53-93%), while low yields were obtained with sterically hindered substrates (3 examples). The reaction was found to go through an in situ generated copper-N-heterocyclic carbene, which was then oxidized into cyclic urea derivatives possessing alkyl, benzyl, aryl, hydroxy, Boc-protected, and tertiary amine groups.
- Li, Dazhi,Ollevier, Thierry
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supporting information
p. 3572 - 3575
(2019/05/24)
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- Mechanochemistry for facilitated access to N,N-diaryl NHC metal complexes
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A user-friendly and solvent-free mechanosynthetic strategy allowed light-sensitive silver(i) complexes featuring N,N-diaryl N-heterocyclic carbenes (NHC), including challenging and sterically hindered ligands, to be yielded efficiently. The first transmet
- Beillard, Audrey,Bantreil, Xavier,Métro, Thomas-Xavier,Martinez, Jean,Lamaty, Frédéric
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p. 1057 - 1063
(2017/02/10)
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- Oxygen-atom insertion of NHCecopper complex: The source of oxygen from N, N-dimethylformamide
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An unprecedented protocol for oxygen-atom insertion reaction of NHCecopper complexes has been developed by employing N,N-dimethylformamide as the oxygen source, which allows the preparation of imidazolinones from carbene complexes and decodes one of the m
- Zeng, Wei,Wang, Enyu,Qiu, Rui,Sohail, Muhammad,Wu, Shaoxiang,Chen, Fu-Xue
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supporting information
p. 44 - 48
(2013/10/08)
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- A direct and practical approach for the synthesis of N-heterocyclic carbene coinage metal complexes
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A novel direct and practical synthetic route leading to N-heterocyclic carbene coinage metal complexes has been developed by using air stable, commercial available Au(III) salt [MAuCl4·2H2O], CuCln (n=1,2) or AgCl, and imidazolium salts as starting materials. The reaction proceeded without sacrificing carbene transfer agent (Ag 2O) or using highly sensitive free NHC.
- Zhu, Shifa,Liang, Renxiao,Jiang, Huanfeng
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p. 7949 - 7955
(2012/09/22)
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- PKas of the conjugate acids of N-heterocyclic carbenes in water
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pKa values of 19.8-28.2 are reported for the conjugate acids of a large series of NHCs in water. The effects of ring size, N-substituent and C(4)-C(5) saturation on pKa are discussed.
- Higgins, Eleanor M.,Sherwood, Jennifer A.,Lindsay, Anita G.,Armstrong, James,Massey, Richard S.,Alder, Roger W.,O'Donoghue, Annmarie C.
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p. 1559 - 1561
(2011/03/22)
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- PREPARATION OF SATURATED IMIDAZOLINIUM SALTS AND RELATED COMPOUNDS
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Methods for the preparation of saturated imidazolinium salts and related compounds that comprises reaction of formamidines with compounds such as dihaioethane and an optional base are disclosed. Alternatively, the imidazoünium salts and related compounds can be prepared in a one-step process without purification of the formamidine reactant. These methods make it possible to obtain numerous imidazolinium salts and related compounds under solvent-free reaction conditions and in excellent yields.
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Page/Page column 11; 19-20
(2009/06/27)
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- A facile preparation of imidazolinium chlorides
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A process for the preparation of symmetric and unsymmetric imidazolinium chlorides that involves reaction of a formamidine with dichloroethane and a base (a) is described. This method makes it possible to obtain numerous imidazolinium chlorides under solvent-free reaction conditions and in excellent yields with purification by simple filtration. Alternatively, symmetric imidazolinium chlorides can be prepared directly in moderate yields from substituted anilines by utilizing half of the formamidine Intermediate as sacrificial base (b).
- Kuhn, Kevin M.,Grubbs, Robert H.
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supporting information; experimental part
p. 2075 - 2077
(2009/04/10)
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- Probing the efficiency of N-heterocyclic carbene promoted O- to C-carboxyl transfer of oxazolyl carbonates
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(Chemical Equation Presented) Screening of a range of azolium salts, bases and solvents for reactivity indicates that triazolinylidenes, generated in situ with KHMDS in THF, promote the Steglich rearrangement of oxazolyl carbonates with high catalytic efficiency (typical reaction time 5 min at 1.5 mol % NHC). This protocol shows wide substrate applicability, even allowing the efficient generation of vicinal quaternary centers. An improved experimental procedure is also described that allows a simplified one-pot reaction protocol to be employed with similarly high catalytic efficiency.
- Thomson, Jennifer E.,Campbell, Craig D.,Concellon, Carmen,Duguet, Nicolas,Rix, Kathryn,Slawin, Alexandra M. Z.,Smith, Andrew D.
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p. 2784 - 2791
(2008/09/20)
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- Microwave-assisted synthesis of N-heterocyclic carbene precursors
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A very simple and efficient procedure is reported for the synthesis of 1,3-diarylimidazolinium chlorides by cyclization of N,N′- diarylethylenediamines dihydrochlorides with triethyl orthoformate under microwave irradiation. Georg Thieme Verlag Stuttgart.
- Aidouni, Adila,Demonceau, Albert,Delaude, Lionel
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p. 493 - 495
(2007/10/03)
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- Catalyst system comprising transition metal and imidazoline-2-ylidene or imidazolidine-2-ylidene
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This invention provides a catalyst system useful in many coupling reactions, such as Suzuki, Kumada, Heck, and amination reactions. The catalyst system of the present invention makes use of N-heterocyclic carbenes or their protonated salts. The compositio
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- Amination reactions of aryl halides with nitrogen-containing reagents mediated by palladium/imidazolium salt systems
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Nucleophilic N-heterocyclic carbenes have been conveniently used as catalyst modifiers in amination reactions involving aryl chlorides, aryl bromides, and aryl iodides with various nitrogen-containing substrates. The scope of a coupling process using a Pd(0) or Pd(II) source and an imidazolium salt in the presence of a base, KOtBu or NaOH, was tested using various substrates. The Pd2(dba)3/IPr·HCl (1, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) system presents the highest activity with respect to electron-neutral and electron-rich aryl chlorides. The ligand is also effective for the synthesis of benzophenone imines, which can be easily converted to the corresponding primary amines by acid hydrolysis. Less reactive indoles were converted to N-aryl-substituted indoles using as supporting ligand the more donating SIPr·HCl (5, SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene). The Pd(OAc)2/SIPr·HCl/NaOH system is efficient for the N-arylation of diverse indoles with aryl bromides. The general protocol developed has been applied successfully to the synthesis of a key intermediate in the synthesis of an important new antibiotic. Mechanistically, palladium-to-ligand ratio studies strongly support an active species bearing one nucleophilic carbene ligand.
- Grasa,Viciu,Huang,Nolan
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p. 7729 - 7737
(2007/10/03)
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- Imidazolylidenes, imidazolinylidenes and imidazolidines
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Starting from glyoxal, 1,3-diarylimidazolinium chlorides 3 were obtained in a three-step sequence via the diimines (1) and ethylene diamine dihydrochlorides (2). Reduction of 1,3-diarylimidazolinium chlorides (3) with lithium alumnium hydride furnished the 1,3- diarylimidazolidines (4) while their deprotonation with potassium hydride in thf gave access to stable carbenes (1,3-diarylimidazolin-2-ylidenes, 5). Similarly substituted imidazol-2-ylidenes are described for comparison.
- Arduengo III, Anthony J.,Krafczyk, Roland,Schmutzler, Reinhard,Craig, Hugh A.,Goerlich, Jens R.,Marshall, William J.,Unverzagt, Markus
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p. 14523 - 14534
(2007/10/03)
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