نتایج جستجو برای: heterocyclic carbenes

تعداد نتایج: 9891  

Journal: :Dalton transactions 2014
F Hackenberg M Tacke

Benzyl-substituted metallocarbene compounds synthesised by our group and others during the past 5 years give a new perspective on their activity as antibiotic and antitumoral drugs. N-heterocyclic carbenes containing an imidazole core were functionalised and their transition metal complexes (M = Ag, Au, Cu, Ru) have shown promising antibacterial as well as anticancer activity in vitro and in vi...

Journal: :Journal of the American Chemical Society 2011
Daniel A DiRocco Tomislav Rovis

An asymmetric intermolecular Stetter reaction of enals with nitroalkenes catalyzed by chiral N-heterocyclic carbenes has been developed. The reaction rate and efficiency are profoundly impacted by the presence of catechol. The reaction proceeds with high selectivities and affords good yields of the Stetter product. Internal redox products were not observed despite of the protic conditions. The ...

Journal: :Journal of the American Chemical Society 2009
William D Jones

N-Heterocyclic carbenes, or NHCs as they are commonly abbreviated, have attracted significant interest over the past decade due to their widespread utility in chemical transformations. As ligands on transition metals, NHCs have been found to have properties similar to those of the widely employed phosphine ligand, due to their ability to act as both a Lewis base and a Lewis acid at the same tim...

Journal: :Chemistry 2018
Stefan Vanicek Maren Podewitz Christopher Hassenrück Michael Pittracher Holger Kopacka Klaus Wurst Thomas Müller Klaus R Liedl Rainer F Winter Benno Bildstein

Oxidative addition of cobaltoceniumdiazonium bis(hexafluoridophosphate) with (pseudo)halide aurates gave gold(III) complexes containing zwitterionic cobaltoceniumide as a ligand. Its selenium derivative, cobaltoceniumselenolate, was obtained by an electrophilic aromatic substitution reaction of iodocobaltocenium iodide with Na2 Se. Spectroscopic and structural data in combination with DFT calcu...

2014
Johann Hlina Judith Baumgartner Christoph Marschner Lena Albers Thomas Müller Viatcheslav V Jouikov

In the presence of PMe3 or N-heterocyclic carbenes, the reaction of oligosilanylene dianions with GeCl2⋅dioxane gives germylene-base adducts. After base abstraction, the free germylenes can dimerize by formation of a digermene. An electrochemical and theoretical study of a bicyclic tetrasilylated digermene revealed formation of a comparably stable radical anion and a more reactive radical catio...

2015
James J Douglas Gwydion Churchill Alexandra M Z Slawin David J Fox Andrew D Smith

Stereo- and chemodivergent enantioselective reaction pathways are observed upon treatment of alkylarylketenes and trichloroacetaldehyde (chloral) with N-heterocyclic carbenes, giving selectively either β-lactones (up to 88:12 dr, up to 94 % ee) or α-chloroesters (up to 94 % ee). Either 2-arylsubstitution or an α-branched iPr alkyl substituent within the ketene favours the chlorination pathway, ...

Journal: :Molecules 2009
Elliot Ennis Scott T Handy

A convenient route for the preparation of C2-substituted imidazolium ionic liquids is reported. This method involves the alkylation of N-heterocyclic carbenes, which are readily generated from the C2-unsubstituted imidazolium ionic liquids. It works well for non-functionalized alkyl chlorides, and less well for alkyl bromides and iodides, likely due to competing elimination reactions. The resul...

2016
Marta Malinowska Mariana Kozlowska Agnieszka Hryniewicka Stanisław Witkowski Jacek W. Morzycki

ABSTRACT New indenylidene-type second generation catalysts bearing modified unsymmetrically substituted N-heterocyclic carbene ligands were synthesized. The complexes contain an N-mesityl and N'-nitrobenzyl substituted NHC ligand. The precursors of free carbenes-imidazolinium salts-were obtained in an easy and environment-friendly way (under aqueous or neat conditions). The new catalysts were p...

Journal: :Dalton transactions 2015
Priyam Bharadwaz Bitupon Borthakur Ashwini K Phukan

Theoretical calculations were carried out to understand the effect of annulation on the electronic and ligand properties of boron substituted N-heterocyclic carbenes (B-NHCs). Annulation results in a decrease in stability as indicated by the calculated values of singlet-triplet separations and stabilization energies as well as HOMO-LUMO gaps. Annulated B-NHCs are found to be weaker σ-donors but...

Journal: :Angewandte Chemie 2023

Combining N-heterocyclic carbenes with gold nanoparticles provides an ultrabright and fragment-free ionization platform for laser-desorption mass spectrometry. In their Research Article (e202219182), David M. Jenkins, Jon P. Camden, co-workers show that NHC-functionalized can “give wings” in the spectrometer, enabling next-generation applications of barcoding, data storage, bioconjugation react...

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