نتایج جستجو برای: friedel
تعداد نتایج: 1232 فیلتر نتایج به سال:
The first total synthesis of monosporascone is presented. The five-step synthesis developed includes a silver acetylide-acid chloride coupling, domino Diels-Alder-retro-Diels-Alder reaction, and an intramolecular Friedel-Crafts acylation, and provides the natural product in 57% yield overall. Selective reduction of monosporascone also afforded the related metabolite dihydromonosporascone.
We discuss the emergence of symmetry-breaking via the Pomeranchuk instability from interactions that respect the underlying point-group symmetry. We use a variational mean-field theory to consider a 2D continuum and a square lattice. We describe two experimental signatures: a symmetry-breaking pattern of Friedel oscillations around an impurity; and a structural transition.
[reaction: see text] A series of carbazole/fluorene (CBZm-Fn) hybrids were effectively synthesized through Friedel-Crafts-type substitution of the carbazole rings. These compounds were thermally and morphologically stable host materials for OLED applications. Efficient blue phosphorescent OLEDs were obtained when employing CBZ1-F2 as the host and FIrpic as the guest.
An unusual increase of the conductance with temperature is observed in clean quantum point contacts for conductances larger than 2(e2/h). At the same time, a positive magnetoresistance arises at high temperatures. A model accounting for electron-electron interactions mediated by boundaries (scattering on Friedel oscillations) qualitatively describes the observation. It is supported by a numeric...
Solvents and catalysts for organic reactions: Friedel-Crafts reactions, Alkylation, Izomerisation, Acylation, Esterification, Cracking, Diels-Alder addition, Wittig reactions, Polymerisation. Solvents in separation processes: Extraction of metals and organic compounds, Nuclear wastewater treatment, Production of selective liquid membranes and sensors. Others:...
We report here a novel synthesis of optically active bishomotyrosine. The bishomotyrosine skeleton was constructed by using a Friedel-Crafts reaction between phenol and optically active N-Tfa-Glu(Cl)-OMe in triflic acid under the mild condition. Reduction and subsequent deprotection then afforded bishomotyrosine derivatives without any loss of optical purity.
A large part of the scientific legacy Maurice Kleman concerns topological defects in liquid crystals. Here, we focus on very first article crystals coauthored with Jacques Friedel and devoted to linear cholesterics discovered 1921 by François Grandjean who observed them wedges made from partially cleaved mica sheets. interpreted thin (single) thick (double) lines as dislocations Burgers vectors...
A facile synthesis of a series of benzene ring acylated analogues of harmaline has been achieved by Friedel-Crafts acylation under solvent-free conditions at room temperature using acyl halides/acid anhydrides and AlCl3. The reaction afforded 10- and 12-acyl analogues of harmaline in good yield, along with minor quantities of N-acyl-tryptamines and 8-acyl analogues of N-acyltryptamines.
A regioselective efficient synthetic approach to N-imino-γ-carbolinium ylides via AgOTf-catalyzed iminoannulation has been developed. This transformation proceeds via a silver(i) triflate-catalyzed consecutive Friedel-Crafts reaction/N-C bond formation sequence between the readily available indole derivatives and propargylic alcohols.
This note provides a summary of the meaning of the term ‘Superselection Rule’ in Quantum Mechanics and Quantum-Field Theory. It is a contribution to the Compendium of Quantum Physics: Concepts, Experiments, History and Philosophy, edited by Friedel Weinert, Klaus Hentschel, Daniel Greenberger, and Brigitte Falkenburg.
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