نتایج جستجو برای: nhc

تعداد نتایج: 1697  

Journal: :Chemical communications 2014
Christian Richter Kira Schaepe Frank Glorius Bart Jan Ravoo

N-heterocyclic carbenes (NHCs) represent a leading class of ligands in organometallic chemistry, but have been rarely exploited as stabilizers for metal nanoparticles (NPs). We report the first example of NHC stabilized Pd-NPs that demonstrate long term stability. These NHC Pd-NPs were synthesized by a facile ligand exchange protocol using rationally designed long chained NHCs (LC-NHCs). Furthe...

Journal: :Chemical communications 2012
Amit Pratap Singh Rajendra S Ghadwal Herbert W Roesky Julian J Holstein Birger Dittrich Jean-Philippe Demers Veniamin Chevelkov Adam Lange

An abnormal N-heterocyclic carbene (aNHC) has been used as a Lewis base to initiate dismutation of trichlorosilane. This report presents the reactivity differences of a normal N-heterocyclic carbene (NHC) versus aNHC with heavier group 14 elements. Three novel compounds (NHC)(2)·SiCl(2)H(2) (2), aNHC·SiCl(2)H(2) (3), and aNHC·GeCl(2) (4) have been synthesized and characterized by single crystal...

2012
Stefan Warsink Andreas Roodt

In the title compound, [PdCl(2)(C(21)H(23)N(3)O)(2)], the Pd(II) atom is located on an inversion centre and is coordinated in a slightly distorted square-planar environment by the chloride and N-heterocyclic carbene (NHC) ligands in mutual trans positions. There are several hydrogen-bonding inter-actions, the most significant of which is a hydrogen bond between the amide moiety of the NHC and t...

Journal: :Journal of the American Chemical Society 2014
Ming Wang Zhijian Huang Jianfeng Xu Yonggui Robin Chi

The first N-heterocyclic carbene (NHC)-catalyzed [3+4] cycloaddition of azomethine imines and enals is disclosed. Oxidative catalytic remote activation of enals affords 1,4-dipolarophile intermediates that react with 1,3-dipolar azomethine imines to generate dinitrogen-fused seven-membered heterocyclic products with high optical purities. Our approach also provides effective kinetic resolution ...

Journal: :Journal of the American Chemical Society 2015
Tingshun Zhu Chengli Mou Baosheng Li Marie Smetankova Bao-An Song Yonggui Robin Chi

An N-heterocyclic carbene (NHC) catalyzed domino reaction triggered by a δ-LUMO activation of α,β-γ,δ-diunsaturated enal has been developed for the formal [4 + 2] construction of multisubstituted arenes and 3-ylidenephthalide. These two products, formed in a highly chemo- and regioselective manner, were obtained via different catalytic pathways due to a simple change of the substrate. The activ...

Journal: :Chemical communications 2014
Arturo Juzgado M Mercedes Lorenzo-García Myriam Barrejón Ana M Rodríguez Julián Rodríguez-López Sonia Merino Juan Tejeda

A C(4)-bound palladium-N-heterocyclic carbene (4) was selectively obtained from the C(2)-unsubstituted imidazolium salt 3. The higher stability of the C(4) versus the C(2)-bound carbene complex due to pyridine chelation assistance allowed this mesoionic compound to be obtained.

2014
Elliot J Lawrence Thomas J Herrington Andrew E Ashley Gregory G Wildgoose

In order to use H2 as a clean source of electricity, prohibitively rare and expensive precious metal electrocatalysts, such as Pt, are often used to overcome the large oxidative voltage required to convert H2 into 2 H(+) and 2 e(-). Herein, we report a metal-free approach to catalyze the oxidation of H2 by combining the ability of frustrated Lewis pairs (FLPs) to heterolytically cleave H2 with ...

2015
Agnès LABANDE Eric DEYDIER Eric MANOURY Jean-Claude DARAN Catherine AUDIN Rinaldo POLI

In this account the authors’ latest results in C–C coupling catalysis are reviewed. First, an efficient catalytic system for the Kumada–Tamao–Corriu coupling reaction based on NHC-phosphine (NHC = N-heterocyclic carbene) nickel complexes is presented. Then the use of palladium complexes of chiral ferrocenyl NHC-phosphines in the asymmetric Suzuki–Miyaura coupling reaction is reported. High cata...

Journal: :Organic & biomolecular chemistry 2010
Luis R Domingo Ramón J Zaragozá Manuel Arnó

The N-heterocyclic carbene (NHC) catalyzed addition of enals to enones to yield trans-cyclopentenes has been investigated using DFT methods at B3LYP/6-31G** computational level. This NHC catalyzed reaction comprises several steps. The first one is the formation of a Breslow intermediate, which nucleophilically attacks to the conjugated position of the enone to yield an enol-enolate. This second...

2013
Johann Hlina Judith Baumgartner Christoph Marschner Patrick Zark Thomas Müller

Reaction of the PEt3 adduct of a disilylated five-membered cyclic germylene with group 4 metallocene dichlorides in the presence of magnesium led to the formation of the respective germylene metallocene phosphine complexes of titanium, zirconium, and hafnium. Attempts to react the related NHC adduct of a disilylated four-membered cyclic germylene under the same conditions with Cp2TiCl2 did not ...

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