250285-32-6Relevant articles and documents
Biscarbene palladium(II) complexes. reactivity of saturated versus unsaturated N-heterocyclic carbenes
Fu, Ching-Feng,Lee, Chun-Chin,Liu, Yi-Hung,Peng, Shie-Ming,Warsink, Stefan,Elsevier, Cornelis J.,Chen, Jwu-Ting,Liu, Shiuh-Tzung
, p. 3011 - 3018 (2010)
A series of designed palladium biscarbene complexes including saturated and unsaturated N-heterocyclic carbene (NHC) moieties have been prepared by the carbene transfer methods. All of these complexes have been characterized by 1H and 13C NMR spectroscopy as well as X-ray diffraction analysis. The reactivity of Pd-C(saturated NHC) is distinct from that of Pd-C(unsaturated NHC). The Pd-C(saturated NHC) bonds are fairly stable toward reagents such as CF3COOH, AgBF4 and I2, whereas Pd-C(unsaturated NHC) bonds are readily cleaved under the similar conditions. Notably, the catalytically activity of these palladium complexes on Suzuki-Miyaura coupling follows the order: (sat-NHC)2PdCl2 > (sat-NHC)(unsat-NHC)PdCl2 > (unsat-NHC)2PdCl2.
Reaction of N-heterocyclic carbene (NHC) with different HF sources and ratios – A free fluoride reagent based on imidazolium fluoride
Ali?, Bla?,Tav?ar, Ga?per
, p. 141 - 146 (2016)
Treatment of N-heterocyclic carbene (1,3-Bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene; (LDipp)) with different sources of hydrofluoric acid (Et3N?3HF, anhydrous hydrofluoric acid and KHF2) in 1:1, 1:2, 1:3 ratios affords [(LDipp)H]+[F]?(1), [(LDipp)H]+[(HF)F]?(2) and [(LDipp)H]+[(HF)2F]?(3) salts respectively. Different fluoride sources all yield the same products, but ease of manipulation and isolation can influence the choice in the future use. Compound (1), which shows characteristics of a free fluoride reagent, can be obtained with good yield and without the contaminants usually present in such compounds. All products were characterized by X-Ray crystallography, NMR spectroscopy and free fluoride (Ff ?) chemical analysis.
Modular Ni(0)/Silane Catalytic System for the Isomerization of Alkenes
Chang, Alison Sy-Min,Cook, Amanda K.,Kawamura, Kiana E.,Martin, Daryl J.,Morris, Parker T.,Smith, Haley M.
supporting information, p. 486 - 496 (2022/03/02)
Alkenes are used ubiquitously as starting materials and synthetic targets in all areas of chemistry. Controlling their geometry and position along a chain is vital to their reactivity and properties yet remains challenging. Alkene isomerization is an atom-economical process to synthesize targeted alkenes, and selectivity can be controlled using transition metal catalysts. The development of mild, selective isomerization reactivity has enabled efficient tandem catalytic systems for the remote functionalization of alkenes, a process in which a starting alkene is isomerized to a new position prior to the functionalization step. The key challenges in developing isomerization catalysts for remote functionalization applications are (i) a lack of modularity in the catalyst structure and (ii) the requirement of nonmodular and/or harsh additives during catalyst activation. We address both challenges with a modular (NHC)Ni(0)/silane catalytic system (NHC, N-heterocyclic carbene), demonstrating the use of triaryl silanes and readily accessible (NHC)Ni(0) complexes to form the proposed active (NHC)(silyl)Ni-H species in situ. We show that modification of the steric and electronic nature of the catalyst via modification of the ancillary ligand and silane partner, respectively, is easily achieved, creating a uniquely versatile catalytic system that is effective for the formation of internal alkenes with high yield and selectivity for the E-alkene. The use of silanes as mild activators enables isomerization of substrates with a variety of functional groups, including acid-labile groups. The broad substrate scope, enabled by catalyst design, makes this catalytic system a strong candidate for use in tandem catalytic applications. Preliminary mechanistic studies support a Ni-H insertion/elimination pathway.
Preparation method of NHC-PdCl2-3-chloropyridine complex
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Paragraph 0029; 0033-0035; 0041-0042; 0043-0044; 0045-0046, (2021/05/08)
The invention relates to a preparation method of an NHC-PdCl2-3-chloropyridine complex. The preparation method comprises the following steps: subjecting 2,6-diisopropylaniline, glyoxal and acetic acid to reacting in an ethanol solvent for 2-4 days to obtain glyoxal-bis-(2,6-diisopropylphenyl)imine; stirring a mixed solution of glyoxal-bis-(2,6-diisopropylphenyl)imine, chloromethylethyl ether, tetrahydrofuran and water at 30-50 DEG C for a reaction for 10-20 hours to obtain 1,3-bis-(2,6-diisopropylphenyl)imidazolium chloride, wherein a molar ratio of glyoxal-bis-(2,6-diisopropylphenyl)imine to water is 1: (2-10); and subjecting 1,3-bis-(2,6-diisopropylphenyl)imidazolium chloride, palladium chloride, cesium carbonate and 3-chloropyridine to reacting for 10-20 hours at a temperature of 60-100 DEG C to obtain [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium (II) dichloride. The method has the advantages that raw materials are easy to obtain, operation is simple, reaction conditions are mild and easy to control and industrial mass production is easy.
Application of Quantitative 1H and 19F NMR to Organometallics
Akhdar, Ayman,Andanson, Jean-Michel,Faure, Sophie,Gautier, Arnaud,Tra?kia, Mounir
, (2021/08/03)
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.