نتایج جستجو برای: Carbene reaction

تعداد نتایج: 419291  

Journal: :journal of physical & theoretical chemistry 2008
saeid abedini khoramie shahram moradi somayeh miryousefi samira eftekharjoo

the reaction mechanism between (h2c) and (7, 0), zigzag single-walled carbon nanotubes(zswcnts) on two different orientation of c-c have been studied by semi empirical am!method. the activation barriers of (h2c) adding to (7, 0) zswcnt are computed and compared.the effects of diameters of zigzag swcnt on their binding energies were studied

2017
Xingkuan Chen Hongling Wang Kazuki Doitomi Chong Yih Ooi Pengcheng Zheng Wangsheng Liu Hao Guo Song Yang Bao-An Song Hajime Hirao Yonggui Robin Chi

The research in the field of asymmetric carbene organic catalysis has primarily focused on the activation of carbon atoms in non-aromatic scaffolds. Here we report a reaction mode of carbene catalysis that allows for aromatic aldehyde activation and remote oxygen atom functionalization. The addition of a carbene catalyst to the aldehyde moiety of 2-hydroxyl aryl aldehyde eventually enables dear...

2002
Gefei Wu B. F. Bartlett W. T. Tysoe

Carbene species are grafted onto Mo(100) by the thermal decomposition of methylene iodide, where the decomposition is followed using ultraviolet photoelectron spectroscopy. Carbenes hydrogenate to methane by reaction with surface hydrogen via a secondorder reaction with an activation energy of 21 ___ 2 kJ mol1. Experiments with deuterium show that there appears to be no hydrogendeuterium exchan...

Journal: :Journal of the American Chemical Society 2005
Brandon R Galan Milan Gembicky Paulina M Dominiak Jerome B Keister Steven T Diver

In the presence of carbon monoxide, ruthenium carbenes give a net insertion/ring expansion (Buchner reaction) into one of the aromatic rings of the N-heterocyclic carbene ligand. In alkene metathesis applications, the N-heterocyclic carbene ligand is both robust and typically inert to reactions with the metal-bound carbene. This unique reaction is completely regioselective. The complexes obtain...

Journal: :Nature Chemistry 2015

Journal: :Organic & biomolecular chemistry 2015
Lei Wang Zhen Chen Manyuan Ma Wenzeng Duan Chun Song Yudao Ma

An enantioselective conjugate addition of boron to α,β-unsaturated ketones catalysed by either a N-heterocyclic carbene or a copper-carbene complex generated in situ from a new chiral bicyclic triazolium based on [2.2]paracyclophane is presented. The dual chiral carbene-copper catalyst has significant advantages over its carbene counterpart as an organocatalyst in asymmetric β-boration of acycl...

Journal: :Chemical communications 2012
Ana Petronilho Helge Müller-Bunz Martin Albrecht

Reaction of CsOH with triazolium salts affords mesoionic compounds containing an exocyclic oxygen; the same product is obtained by reaction of the corresponding Cu(I) triazolylidenes with CsOH and represents an unusual reactivity pattern of N-heterocyclic carbene precursors that has implications for carbene copper-catalyzed reactions.

Journal: :Dalton transactions 2008
Matthew R Crittall Charles E Ellul Mary F Mahon Olly Saker Michael K Whittlesey

The first examples of abnormal coordination of Ardeungo's carbene, 1,3-bis-adamantylimidazol-2-ylidene, have been isolated and structurally characterised following reaction of the free carbene with the trinuclear clusters M(3)(CO)(12) (M = Ru, Os).

Journal: :Chemical communications 2009
Swee Kuan Yen David J Young Han Vinh Huynh Lip Lin Koh T S Andy Hor

The reaction of [Pt(II)(2-phenylpyridine)(acac)] and benzothiazolium bromide yields the N,S-heterocyclic carbene ligand trans to pyridyl while, surprisingly, a very similar N,N-heterocyclic carbene coordinates predominantly trans to the cyclometallated carbon.

Journal: :Journal of the American Chemical Society 2016
Xingkuan Chen Jacqueline Zi Mei Fong Jianfeng Xu Chengli Mou Yunpeng Lu Song Yang Bao-An Song Yonggui Robin Chi

Carbene-catalyzed reaction of carboxylic esters has the potential to offer effective synthetic solutions that cannot be readily achieved by using the more conventional aldehyde-type substrates. Here we report the first carbene-catalyzed dynamic kinetic resolution of α,α-disubstituted carboxylic esters with up to 99:1 er and 99% yield. The present study clearly illustrates the unique power of ca...

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