نتایج جستجو برای: carbene reaction

تعداد نتایج: 419291  

Journal: :Journal of the American Chemical Society 2009
Stephen P Lathrop Tomislav Rovis

A one-pot, asymmetric multicatalytic formal [3+2] reaction between 1,3-dicarbonyls and alpha,beta-unsaturated aldehydes is described. The multicatalytic process involves a secondary amine catalyzed Michael addition followed by a N-heterocyclic carbene catalyzed intramolecular crossed benzoin reaction to afford densely functionalized cyclopentanones with high enantioselectivities. The reaction p...

2004
Guan-Wu Wang Yu-Jin Li Ru-Fang Peng Zhen-Hua Liang You-Cheng Liu

[60]Fullerene-fused pyrazolines 1 were prepared by the reaction of C60 with alky diazoacetates under the solid-state high-speed vibration milling conditions as well as in toluene solution. Pyrazolines 1 were stable in refluxing toluene and its thermolysis process in 1,2-dichlorobenzene was investigated, the decomposition rates and activation energies of pyrazolines 1 were obtained. The current ...

Journal: :Chemistry 2014
Linda Ta Anton Axelsson Joachim Bijl Matti Haukka Henrik Sundén

Imidazolium-based ionic liquids (ILs) serve both as recyclable reaction media and as precatalysts for the N-heterocyclic carbene-catalyzed conjugate addition of α,β-unsaturated aldehydes to chalcones. The reaction produces a broad scope of 1,6-ketoesters incorporating an anti-diphenyl moiety in high yields and with high stereoselectivity. In recycling experiments, the IL can be reused up to fiv...

2017
Jiwei Wang Xiaoming Cao Shichang Lv Caiyun Zhang Sheng Xu Min Shi Jun Zhang

Metal carbenes are often proposed as reactive intermediates in the late transition metal-catalysed transformations of alkynes. Owing to their high reactivity, however, isolation and structural characterization of metal carbene intermediates in these transformations has remained unknown. Herein, we report the isolation of two acyclic gold and copper carbene intermediates in either Au(I)- or Cu(I...

Journal: :ACS Catalysis 2021

A common challenge in molecular electrocatalysis is the relationship between maximum activity and overpotential required to reach that rate, with faster catalysts incurring higher overpotentials. This work follows a strategy based on independent tuning of ligands primary coordination sphere discover previously unreported iron catalyst for CO2 reduction than similar complexes while maintaining s...

Journal: :Journal of the American Chemical Society 2004
Emmanuelle Despagnet-Ayoub Robert H Grubbs

The synthesis of the first four-membered N-heterocyclic carbene is described. Depending on the substituents on the nitrogen atoms, it is possible to characterize at room temperature the carbene dimer or the free carbene. Crystallographic analyses are provided for these carbene species.

Journal: :Current opinion in biotechnology 2017
Oliver F Brandenberg Rudi Fasan Frances H Arnold

The surge in reports of heme-dependent proteins as catalysts for abiotic, synthetically valuable carbene and nitrene transfer reactions dramatically illustrates the evolvability of the protein world and our nascent ability to exploit that for new enzyme chemistry. We highlight the latest additions to the hemoprotein-catalyzed reaction repertoire (including carbene Si-H and C-H insertions, Doyle...

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