Cu(I)–N-heterocyclic carbene-catalyzed base free C–N bond formation of arylboronic acids with amines and azoles
A new N-heterocyclic carbene (NHC) precursor of imidazolium chloride and its corresponding Cu(I)–NHC complex 1 was synthesized. The complex 1 was found to be a highly effective catalyst for Chan-Evans-Lam coupling of arylboronic acid with amines and azoles (including imidazole, pyrazole and triazole), without addition of base at room temperature. Various substituents on three substrates can be tolerated, giving the desired coupling products in good to excellent yields (62–94%). The method is practical and offers an alternative to the corresponding copper-catalyzed Chan-Evans-Lam process for the construction of C–N bonds.
Zhang, Maoyuan,Xu, Zengbing,Shi, Dabin
(2020/12/25)
Confinement of a Au-N-heterocyclic carbene in a Pd6L12metal-organic cage
A Au(i)-N-heterocyclic-carbene (NHC)-edged Pd6L12 molecular metal-organic cage is assembled from a Au(i)-NHC-based bipyridyl bent ligand and Pd2+. The octahedral cage structure is unambiguously established by NMR, electrospray ionization-mass spectrometry and single crystal X-ray crystallography. The electrochemical behaviour was analyzed by cyclic voltammetry. The octahedral cage has a central cavity for guest binding, and is capable of encapsulating PF6- and BF4- anions within the cavity. This journal is
Synthesis of Pd Complexes Containing Tailed NHC Ligands and Their Use in a Semicontinuous Membrane-Assisted Suzuki Cross-Coupling Process
Homogeneous catalysis has proved to be a reliable method for preparing numerous molecular entities, but catalysts can be expensive and difficult to remove. Because of this, industry targets catalysts that are easily separated and recovered and feature increased turnover numbers. The ongoing shift from multipurpose batch reactors toward continuous manufacturing in fine chemicals synthesis results in a new set of catalyst requirements. This paper reports the design and use of Pd complexes suitable for a semicontinuous Suzuki cross-coupling reaction based on a membrane-assisted reactor. These Pd complexes contain tailed N-heterocyclic carbene (NHC) ligands, allowing internal catalyst recovery by organic solvent nanofiltration with top-layer-modified ceramic membranes. These membranes give selective nanofiltration of the catalyst based on a combination of size exclusion and affinity separation (solvent-solute-membrane interactions). The semicontinuous system developed led to significantly improved turnover numbers, simplified product isolation, and consequently reduced mass intensity by simply adding more of the reactants and reagents to the reaction vessel.
Ormerod, Dominic,Dorbec, Matthieu,Merkul, Eugen,Kaval, Nadya,Lefèvre, Nicolas,Hostyn, Steven,Eykens, Lies,Lievens, Jo,Sergeyev, Sergey,Maes, Bert U. W.
p. 1509 - 1517
(2018/10/25)
Thieme Chemistry Journals Awardees - Where Are They Now? Synthesis of a Dinuclear Copper NHC Complex Bearing a Rigid π-Conjugated Cyclic Framework
Macrocyclic dinuclear complexes have been gaining popularity in the design of homogeneous catalysts. Herein, we report the design of such a complex featuring catalytically active sites fixed inside the ring and its synthesis using a cross-coupling reaction.
Inamori, Daiki,Miwa, Takuya,Fujihara, Tetsuaki,Tsuji, Yasushi,Terao, Jun
p. 1775 - 1779
(2017/11/27)
Synthesis and catalytic application of: N -heterocyclic carbene copper complex functionalized conjugated microporous polymer
A N-heterocyclic carbene copper(i) complex functionalized conjugated microporous polymer (CMP-NHC-CuCl) was synthesized by palladium-catalyzed Sonogashira cross-coupling chemistry. The resulting CMP-NHC-CuCl proved to be a good heterogeneous catalyst in the hydrosilylation of functionalized terminal alkynes with boryldisiloxane to afford (β,β)-(E)-vinyldisiloxane with high stereoselectivity, and the catalyst could be used four times without obvious loss in catalytic activity. Moreover, CMP-NHC-CuCl was also efficient in catalyzing the hydrosilylation of CO2 with triethoxysilane to form silyl formate under mild conditions.
Zhou, Hui,Zhang, Qing-Yong,Lu, Xiao-Bing
p. 44995 - 45000
(2016/06/06)
Unusual mechanistic course of some NHC-mediated transesterifications
During experiments on the transesterification of vinyl benzoate with ethanol mediated by IPr and IMes, unexpected species were observed and characterized that call into question the accepted mechanism of the NHC-mediated transesterification of vinyl ester
Pignataro, Luca,Papalia, Teresa,Slawin, Alexandra M. Z.,Goldup, Stephen M.
supporting information; experimental part
p. 1643 - 1646
(2009/09/06)
CATALYSTS FOR POLYMERIZING CYCLIC OLEFIN
Provided is a metal catalyst complex for preparing a cyclic olefin-based polymer by addition polymerization of a cyclic olefin-based monomer, which is represented by Formula 1 below: [M(L1)x (L'2)y(L3)z]a[Ani]b wherein M is a Group X metal; [M(L1)x (L'2)y(L3)z] is a cationic precatalyst; L1 is an anionic hydrocarbyl-containing ligand; L'2 is a neutral ligand; L3 is an N-heterocyclic carbene ligand; [Ani] is an anion capable of weakly coordinating with the metal M; x is 1 or 2; y is 0 to 4; z is 1 or 2; 2≤x+y+z≤6; a and b are each 1 to 10. The metal catalyst complex has an N-heterocyclic carbene ligand, and thus, is excellent in thermal stability and reactivity.
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Page/Page column 35
(2010/11/26)
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