An electron-withdrawing group was introduced to the α-position of chalcones, and the resulting alkylidene diketones showed new reactivities with enals under the catalysis of N-heterocyclic carbenes (NHCs). Selective activation of enals affords enolate equivalents that undergo highly enantioselective intermolecular Diels-Alder reactions with the alkylidene diketones. No products that might have ...

Novel rhodium(I) complexes with N-heterocyclic carbenes bearing a 2,3,4,5-tetraphenylphenyl and its higher dendritic frameworks were synthesized and the complexes were used as catalysts in rhodium-catalyzed hydrosilylation of alpha,beta-unsaturated ketones to show high 1,4-adduct selectivity.

A novel electrochemical procedure for the preparation of metal complexes of N-heterocyclic carbenes using imidazolium salts or corresponding silver-NHC complexes as carbene sources and electrolytes, and metal plates as the sacrificial anodes is described. The procedure is simple and good yielding without the use of expensive or air-sensitive reagents.

Complexes of N-heterocyclic carbenes (NHCs) with copper(II) halogenides are unstable. Upon formation, these complexes decompose to give haloamidinium salts. Contrastingly, O-substituted copper(II) NHC complexes are fairly stable. A series of new five-, six- and seven-membered ring NHC complexes of Cu(OAc)(2) have been synthesised and characterised in the solid state.

Ethynyldimesitylborane (1) is synthesised via salt elimination and its reactivity towards NHCs is studied. Depending on their size, NHCs attack either at the boron atom or at the β-alkynyl carbon atom. Steric control over the reaction was probed by reactions with N-heterocyclic carbenes yielding a carbene-borane adduct (2), a 1-boraindane (3), and the first structurally characterised borataalle...

A new strategy was developed for the modification of silver(I) and gold(I) N-heterocyclic carbenes. Azido groups were grafted and used either by copper-catalysed azide-alkyne cycloaddition before metallation or by thermal and "strain-promoted" 1,3-dipolar cycloaddition after metallation to functionalise the metal-NHCs.

A new method for the synthesis of industrially important azoimidazolium dyes is presented. The procedure is based on a reagent which is rarely used in the context of synthetic organic chemistry: nitrous oxide ("laughing gas"). N2O is first coupled to N-heterocyclic carbenes. Subsequent reaction with aromatic compounds through an AlCl3-induced C-H activation process provides azoimidazolium dyes ...

The interaction of N,N0-bismesitylimidazolin-2-yl (IMes) with alcohols is discussed. NMR spectroscopy and X-ray crystallography were used to examine the influence of solvent and alcohol on this interaction. The stabilizing effect of these interactions may be used for the storage of nitrogen–heterocyclic carbenes (NHCs) since removal of the volatiles liberates the NHC. 2008 Elsevier Ltd. All rig...

Alkoxide-functionalized N-heterocyclic carbenes (NHCs) stabilise the potassium-imidazole-2-ylidene fragment against 1,2 alkyl rearrangement reactions; this allows the first structural characterisation of a potassium NHC complex, which reveals distorted and unusual bonding interactions between the imidazole ring and the potassium cation.

Herein we report robust methods for the preparation and full characterisation of a range of Ir(I) and Rh(I) fluoride and bifluoride complexes using N-heterocyclic carbenes (NHCs) as ancillary ligands. The processes that link the fluoride and the bifluoride species are investigated and reports of the first Ir-bifluoride and Ir(I)-NHC and Rh(I)-NHC trifluoromethyl complexes are revealed.