نتایج جستجو برای: copper catalysis

تعداد نتایج: 108411  

Journal: :Journal of the American Chemical Society 2012
Eduardas Skucas David W C MacMillan

The enantioselective α-vinylation of aldehydes using vinyl iodonium triflate salts has been accomplished via the synergistic combination of copper and chiral amine catalysis. These mild catalytic conditions provide a direct route for the enantioselective construction of enolizable α-formyl vinylic stereocenters without racemization or olefin transposition. These high-value coupling adducts are ...

Journal: :Chemical communications 2012
Arnold J Boersma Bas de Bruin Ben L Feringa Gerard Roelfes

DNA-based catalysis can be used to control the enantioselectivity of copper-catalysed Diels-Alder and Friedel-Crafts reactions to produce either enantiomer of the product by changing the denticity of the ligand coordinated to the Cu(II) ion, even though the DNA adopts a right handed helical conformation only.

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: :Journal of the American Chemical Society 2009
Yingdong Lu Tim C Johnstone Bruce A Arndtsen

While asymmetric transition-metal catalysis has become a powerful method for constructing chiral products, a challenge in this field is the identification of the correct ligand for high selectivity. We report here a simple approach to chiral catalyst formation: coupling of an available pool of Brønsted acids, namely, amino acid derivatives, with tunable ligands on copper catalysts. This system ...

Journal: :Journal of the American Chemical Society 2013
Ryan W Evans Jason R Zbieg Shaolin Zhu Wei Li David W C MacMillan

The direct α-amination of ketones, esters, and aldehydes has been accomplished via copper catalysis. In the presence of catalytic copper(II) bromide, a diverse range of carbonyl and amine substrates undergo fragment coupling to produce synthetically useful α-amino-substituted motifs. The transformation is proposed to proceed via a catalytically generated α-bromo carbonyl species; nucleophilic d...

2014
Michael D. Schulz Manza B. J. Atkinson Rachel J. Elsey Martin M. Thuo

Copper(I) halides are employed as ‘phosphine sponges’ to sequester phosphor-ylides when using phosphine-based Grubb’s metathesis catalysis in polar protic solvents and under heat. These cuprous halides are hypothesized to significantly slow the formation of the ruthenium hydride olefin isomerization catalyst. We demonstrate their use in both cross metathesis and ring-closing metathesis.

Journal: :Journal of the American Chemical Society 2012
Shaolin Zhu David W C MacMillan

An enantioselective arylation-cyclization cascade has been accomplished using a combination of diaryliodonium salts and asymmetric copper catalysis. These mild catalytic conditions provide a new strategy for the enantioselective construction of pyrroloindolines, an important alkaloid structural motif that is commonly found among biologically active natural products.

Journal: :Chemical communications 2013
Rebecca M Maksymowicz Philippe M C Roth Amber L Thompson Stephen P Fletcher

Copper catalysis allows alkyl zirconium species, generated in situ from alkenes, to undergo conjugate addition reactions. A hydrometallation-catalytic asymmetric 1,4-addition was used to synthesize either enantiomer of a natural product in one step from commercially available materials. Hydrometallation-addition sequences applied to steroids containing a cross-conjugated dienone or 1,6-acceptor...

Journal: :Journal of the American Chemical Society 2012
Nicklas Selander Brady T Worrell Stepan Chuprakov Subash Velaparthi Valery V Fokin

A highly efficient and stereoselective arylation of in situ-generated azavinyl carbenes affording 2,2-diaryl enamines at ambient temperatures has been developed. These transition-metal carbenes are directly produced from readily available and stable 1-sulfonyl-1,2,3-triazoles in the presence of a rhodium carboxylate catalyst. In several cases, the enamines generated in this reaction can be cycl...

Journal: :Journal of the American Chemical Society 2013
Jason M Stevens David W C MacMillan

The enantioselective α-alkenylation of aldehydes has been accomplished using boronic acids via the synergistic combination of copper and chiral amine catalysis. The merger of two highly utilized and robust catalytic systems has allowed for the development of a mild and operationally trivial protocol for the direct formation of α-formyl olefins employing common building blocks for organic synthe...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید