نتایج جستجو برای: friedel
تعداد نتایج: 1232 فیلتر نتایج به سال:
Polyfunctionalized carbazole derivatives have been synthesized by a one-pot reaction between indoles and keto-functionalized nitroolefins. The first step is based on Friedel-Crafts followed acid-promoted microwave-assisted intramolecular cyclization.
We report the observation of discrete vortex bound states with energy levels deviating from widely believed ratio 1:3:5 in vortices an iron based superconductor KCa2Fe4As4F2 through scanning tunneling microcopy (STM). Meanwhile Friedel oscillations are also observed for first time related vortices. By doing self-consistent calculations Bogoliubov-de Gennes equations, we find that at extreme qua...
We discuss the electron density oscillations in an interacting onedimensional electron system with an impurity [1]. Under appropriate conditions the wave vector is given by different values kF = kL/R on left/right side of the scatterer, leading to a Landauer dipole formation. While in the non-interacting system the Friedel oscillations possess only one periodicity related to the local kL on the...
As olefinas captodativas 3a e 3b derivadas dos ácidos metacrílico e trans-crotônico foram preparadas. A presença de uma segunda ligação dupla na molécula, atuando como marcador interno, permitiu-nos comparar sua reatividade relativa em reações de Diesl-Alder e Friedel-Crafts. A reatividade foi avaliada com ciclopentadieno (6) atuando como dieno em cicloadição Diels-Alder, e com furano (9) e tio...
Roland Friedel et al. report a method allowing efficient generation of targeted gene knockouts by homologous recombination in mouse ES cells. Current gene targeting techniques use vectors with a strong promoter to drive expression of a selectable antibiotic resistance marker, but such methods usually yield low homologous recombination frequencies because nonhomologous insertions (false positive...
Kinetic analysis was used as a tool for rational optimization of catalytic direct substitution alcohols to enable selective formation ethers, thioethers, and Friedel–Crafts alkylation products using moisture-tolerant commercially available Zr complex.
We use the T-matrix approximation to analyze the effect of a localized impurity on the local density of states in monoand bilayer graphene. For monolayer graphene the Friedel oscillations generated by intranodal scattering obey an inverse-square law, while the internodal ones obey an inverse law. In the Fourier transform this translates into a filled circle of high intensity in the center of th...
The first catalytic enantioselective Prins cyclization is disclosed. The reaction is catalyzed by the combination of a chiral BINOL-derived bis-phosphoric acid and CuCl. The process consists of a tandem Prins/Friedel-Crafts cyclization that affords the hexahydro-1H-benzo[f]isochromenes products with three new contiguous stereogenic centers in high yields, and good enantio- and excellent diaster...
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