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Are There Carbenes in N‐Heterocyclic Carbene Organocatalysis?
Angewandte Chemie International Edition, 2017AbstractAzolium cations are widely employed in organocatalysis to catalyse highly valuable synthetic processes in the presence of a base. These reactions are called “N‐heterocyclic carbene catalysis”, based on the assumption that they are initiated by the formation of a free carbene through deprotonation, which can then react with the substrates and ...
Sascha Gehrke, Oldamur Hollóczki
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Abnormal N-heterocyclic carbenes
Coordination Chemistry Reviews, 2007Abstract Metal NHC complexes have been known for over 50 years, but only during the last 15 have they been studied as potential catalysts. N-heterocyclic carbene (NHC) complexes are often more straightforward to make than the phosphine analogues with which they are often compared, are generally more stable, less odorous and on many occasions have ...
Polly L. Arnold, Stephen Pearson
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F-block N-heterocyclic carbene complexes
Chemical Communications, 2006N-Heterocyclic carbenes (NHCs) can bind as two-electron sigma-donor ligands to lanthanide and actinide metal cations. In this review we summarise how the incorporation of an anionic group (alkoxide or amido), to form heterobidentate NHC ligands, allows the synthesis of a range of f-block NHC adducts.
Arnold, Plly L, Liddle, Stephen T
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A tropylium annulated N-heterocyclic carbene
Chemical Communications, 2020Derivatives of the cationic tropylium annulated imidazolylidene ITrop+ are obtained by hydride abstraction from related cycloheptatriene compounds.
Sebastian Appel +2 more
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N‐Heterocyclic Carbene Stabilized Boryl Radicals
Angewandte Chemie International Edition, 2016AbstractThe reaction of the 2‐(trimethylsilyl)imidazolium triflate 9 with diarylboron halides (4‐R‐C6H4)2BX (R=H, X=Br; R=CH3, X=Cl; R=CF3, X=Cl) afforded the NHC‐stabilized borenium cations 10 a–c. Cyclic voltammetry revealed a linear correlation between the Hammett parameter σp of the para substituent and the half‐wave potential.
Miguel F. Silva Valverde +6 more
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Anionic tethered N-heterocyclic carbene chemistry
Chemical Society Reviews, 2007Since the discovery of a stable "bottleable" N-heterocyclic carbene (NHC), there has been a spectacular explosion of interest in this ligand class. This interest stems from a desire to understand the fundamentals of the structure and bonding of these systems, but also because of their numerous and emerging applications in small molecule activation ...
Liddle, S T, Edworthy, I S, Arnold, P L
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N‐Heterocyclic Carbene Catalyzed Domino Reactions
Angewandte Chemie International Edition, 2011AbstractWhile organocatalyzed domino reactions or “organocascade catalysis” developed into an important tool in synthetic chemistry during the past decade, the utility of N‐heterocyclic carbenes (NHCs) as catalysts in domino reactions has only received growing attention in the past three years.
André, Grossmann, Dieter, Enders
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2010
Over the last fifteen years, N-heterocyclic carbenes (NHCs) have mostly been used as ancillary ligands for the preparation of transition metal-based catalysts. Compared to phosphorus-containing ligands, NHCs tend to bind more strongly to metal centres, avoiding the necessity for the use of excess ligand in catalytic reactions.
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Over the last fifteen years, N-heterocyclic carbenes (NHCs) have mostly been used as ancillary ligands for the preparation of transition metal-based catalysts. Compared to phosphorus-containing ligands, NHCs tend to bind more strongly to metal centres, avoiding the necessity for the use of excess ligand in catalytic reactions.
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Homoleptic Crown N‐Heterocyclic Carbene Complexes
Angewandte Chemie International Edition, 2007The first metal N-heterocyclic carbene complexes derived from a cyclic tetraimidazolium salt show a remarkable versatility of ligand conformation and coordination geometry. With PdII, a mononuclear square-planar complex is obtained, but with CuI and AgI, an unprecedented dinuclear motif with a short metal–metal interaction is observed (see structure; N
McKie, Ross +4 more
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An overview of N-heterocyclic carbenes
Nature, 2014The successful isolation and characterization of an N-heterocyclic carbene in 1991 opened up a new class of organic compounds for investigation. From these beginnings as academic curiosities, N-heterocyclic carbenes today rank among the most powerful tools in organic chemistry, with numerous applications in commercially important processes.
Matthew N, Hopkinson +3 more
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