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Dioxygen activation with both cyclic (amino)(alkyl)carbenes and di(amino)carbenes at ambient temperature is described. Theoretical studies suggest that electron rearrangement from the doubly filled σ orbital of carbene carbon to its vacant p orbital through the π* antibonding orbital of 3O2 can be considered for Ccarbene–O bond formation. [ABSTRACT FROM AUTHOR]

Described here is a chromium-catalyzed alkylative cross-coupling of benzamide derivatives with aliphatic electrophiles under mild conditions. This reaction was promoted by a low-cost and air-stable chromium(iii) chloride salt combined with an N-heterocyclic carbene ligand and phenylmagnesium bromide as a reductant, and probably occurred with low-valent chromium involved in the catalytic cleavage of the ortho-C–H bonds of the benzamide, followed by coupling with the alkyl bromide through a radical-involving mechanism. [ABSTRACT FROM AUTHOR]

Cyclic (amino)(aryl)carbenes (CAArCs) result from the replacement of the alkyl substituent of cyclic (alkyl)- (amino) carbenes (CAACs) by an aryl group. This structural modification leads to enhanced electrophilicity of the carbene center with retention of the high nucleophilicity of CAACs, and therefore CAArCs feature a small singlet-triplet gap. The isoindolium precursors are readily prepared in good yields, and deprotonation at low temperature, in the presence of [RhCl(cod)]2 and [(Me2S)AuCl] lead to air-stable rhodium and gold CAArC-supported complexes, respectively. The rhodium complexes promote the [3+2] cycloaddition of diphenylcyclopropenone with ethyl phenylpropiolate, and induce the addition of 2-vinylpyridine to alkenes by CH activation. The gold complexes allow for the catalytic threecomponent preparation of 1,2-dihydroquinolines from aniline and phenyl acetylene. These preliminary results illustrate the potential of CAArC ligands in transition-metal catalysis. [ABSTRACT FROM AUTHOR]

Abstract: 1-Substituted benzo[b][1,4]diazepines which are difficult to synthesize by traditional methods have been prepared by an Au(I)–N-heterocyclic carbene complex-catalyzed tandem hydroamination/cyclization process. This protocol features the one-pot formation of a seven-membered N-heterocycle via atom-economic hydroamination/cyclization reactions of readily available N-substituted o-phenylenediamines and terminal alkynes. Based on this strategy, fused tricyclic benzo[b][1,4]diazepines have been accessed for the first time. [Copyright &y& Elsevier]

A simple procedure is developed to synthesize benzo[b][1,4]diazepines from o-phenylenediamine derivatives and terminal alkynes using a Au(I)-NHC-complex-catalyzed hydroamination/cyclization process. [ABSTRACT FROM AUTHOR]