In order to determine the influence of the ligands in the catalytic activity, the catalyst loading was reduced. Table 1: Influence of the ITent ligands in gold-catalysed alkyne hydration.
When the catalyst loading was reduced to 0. Once it was shown that the use of the ITent ligands in the gold-catalysed hydration of phenylacetylene did not improve upon the performance of the parent IPr ligand, we explored the behaviour of the [Au ITent NTf 2 ] complexes in the hydration of nitriles. This result encouraged us to test the influence of the ITent ligands in the hydration of nitriles promoted by monogold species. Low catalyst loadings were employed in order to observe the differences between the four catalysts studied.
Table 2: Influence of the ITent ligands in gold-catalysed nitrile hydration. The reactions were conducted under the reported optimised conditions  and were analysed after 20 min. Table 3: Influence of the ITent ligands in the gold-catalysed synthesis of homoallylic ketones. The impact of varying the length of the alkyl chain of the ligands in gold-promoted transformations has been explored. All gold complexes were shown to be active in water inclusive reactions alkyne and nitrile hydration and in the synthesis of homoallylic ketones from allylic alcohols and alkynes.
However, when the performance of the catalysts was compared to that of the parent [Au IPr NTf 2 ] complex, this appeared to be more active than the remaining complexes, showing that an increase of the alkyl chain length of the ligands has a detrimental effect in the gold-mediated transformations selected in this study. Further studies on the catalytic activity of the ITent ligands with different metals are currently ongoing.
Umicore AG is acknowledged for their generous gift of materials. Steven P.
Giorgio Abbiati and Elisabetta Rossi. Manuel R.
Fructos, Juan Urbano, M. Twitter: BeilsteinInst.
Whether a carbene is in the singlet or triplet state depends primarily on the difference in energy between its frontier orbitals—when the FMOs are close in energy, single occupation of each FMO the triplet state is likely. Whittlesey, Jonathan M. Olsen, Satoshi Sakaguchi, G. Haniti S. Divergent reactions of oxindoles with amino alcohols via the borrowing hydrogen process: oxindole ring opening vs. Org, any member class substances containing at least one metal-to-carbon bond which carbon is part an, they have thus attracted increasing interest, mechanistic Details.
Nolan 2. Alba Collado. Scott R. Danila Gasperini.
It was only in the early s that carbenes with the carbene carbon being incorporated in a nitrogen containing heterocycle (N-heterocyclic carbenes or NHCs). N-Heterocyclic Carbenes in Transition Metal Catalysis and Organocatalysis features all catalytic reactions enabled by N-heterocyclic carbenes (NHCs), either .
Sebastien Meiries. Graphical Abstract. Jump to Figure 1. Results and Discussion. Jump to Scheme 1.
Jump to Scheme 2. Supporting Information. Supporting Information File 1: Experimental information and full characterisation of the complexes including a copy of the NMR spectra. Format: PDF Size: 1. Organogold Chemistry.
KGaA: Weinheim, Nature , , Organometallics , 32, Organometallics , 26, Organometallics , 30, References 61, Reference References It seems that you're in Germany. We have a dedicated site for Germany. It was only in the early s that carbenes with the carbene carbon being incorporated in a nitrogen containing heterocycle N-heterocyclic carbenes or NHCs were found to be stable enough to be isolated.
Since the first report on the application of NHCs as ligands in transition metal catalysis in , NHC have found numerous applications and have been established as a versatile and indispensable class of ligands. For many reactions like metathesis or cross-coupling reactions NHCs have often become the ligands of choice, allowing otherwise difficult transformations. In this book leading experts have surveyed major areas of application of NHC metal complexes in catalysis.
go to site The authors have placed a special focus on nickel- and palladium-catalyzed reactions, on applications in metathesis reactions, on oxidation reactions and on the use of chiral NHC-based catalysts. This compilation is rounded out by an introductory chapter and a chapter dealing with synthetic routes to NHC metal complexes. The use of NHC as ligands in catalysis has reached a certain level of maturity and this book allows the reader to get a balanced view of this increasingly important ligand class.
It is divided into seven chapters, each of which is written by an expert on that particular topic, which is reflected in the thoroughness of coverage.
This book should serve as an excellent starting point for those wishing to enter the field, as well as a superb reference book for those already there. Crudden and Jeremy M.