Search results for "coupling [Higgs particle]"

45° sign switching of effective exchange bias due to competing anisotropies in fully epitaxial Co3FeN/MnN bilayers

2017

We report an unusual angular-dependent exchange bias effect in ferromagnet/antiferromagnet bilayers, where both ferromagnet and antiferromagnet are epitaxially grown. Numerical model calculations predict an approximately 45° period for the sign switching of the exchange-bias field, depending on the ratio between magnetocrystalline anisotropy and exchange-coupling constant. The switching of the sign is indicative of a competition between a fourfold magnetocrystalline anisotropy of the ferromagnet and a unidirectional anisotropy field of the exchange coupling. This predicted unusual angular-dependent exchange bias and its magnetization switching process are confirmed by measurements on fully …

A solvent-directed stereoselective and electrocatalytic synthesis of diisoeugenol.

2018

A stereoselective and electrocatalytic coupling reaction of isoeugenol has been reported for the first time in a 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)/boron-doped diamond (BDD) electrode system. This particular C-C bond formation and diastereoselectivity is driven by a solvate interaction between the radical species and another isoeugenol molecule. Due to an electrocatalytic cycle, only understoichiometric amounts of charge are necessary. Since electric current is directly employed as the oxidant, the reaction is metal and reagent-free. In addition, the electrolysis can be conducted in a very simple undivided beaker-type cell under constant current conditions. Therefore, the protocol is …

First copper(I) ferrocenyltetraphosphine complexes: possible involvement in Sonogashira cross-coupling reaction ?

2008

Preparation and characterization of the first examples of copper(I) ferrocenylpolyphosphine complexes are reported. The molecular structure of complex {P,P′,P′′-[1,1′,2,2′-tetrakis(diphenylphosphino)-4,4′-di-tert-butylferrocene]iodocopper(I)} (1) was solved by X-ray diffraction studies, and its fluxional behavior in solution was investigated by VT-31P NMR; both revealed a net triligated coordination preference of the ferrocenyl tetraphosphine Fc(P)4tBu with copper. The tetradentate ligand is an active auxiliary in Sonogashira alkynylation; therefore the general question of copper as a competitive coordination partner in the Pd/Cu-catalyzed Sonogashira reaction was raised and discussed. Elec…

Cover Picture: Selective Synthesis of Partially Protected Nonsymmetric Biphenols by Reagent‐ and Metal‐Free Anodic Cross‐Coupling Reaction (Angew. Ch…

2016

Selective Formation of 4,4'-Biphenols by Anodic Dehydrogenative Cross- and Homo-Coupling Reaction.

2019

A simple and selective electrochemical synthesis by dehydrogenative coupling of unprotected 2,6- or 2,5-substituted phenols to the desired 4,4'-biphenols is reported. Using electricity as the oxidizing reagent avoids pre-functionalization of the starting materials, since a selective activation of the substrates takes place. Without the necessity for metal-catalysts or the use of stoichiometric reagents it is an economic and environmentally friendly transformation. The elaborated electrochemical protocol leads to a broad variety of the desired 4,4'-biphenols in a very simplified manner compared to classical approaches. This is particular the case for the cross-coupled products.

Mild, Fast, and Easy To Conduct MoCl5-Mediated Dehydrogenative Coupling Reactions in Flow

2018

A convenient and straightforward approach to performing oxidative coupling reactions in flow is presented. A collection of electron-rich benzene derivatives was subjected to this protocol, and the distinct utility of molybdenum pentachloride (MoCl5) is established. Using this unexplored protocol, biphenyls could be obtained in 21–91% isolated yield. This simple protocol opens a new chapter in reagent-mediated dehydrogenative coupling reactions, and yields are compared to classical approaches.

Towards the synthesis of substituted porphyrins by a pyridyl group bearing a reactive functionality

2010

Pyridyl-substituted porphyrins bearing a reactive functionality were prepared via Suzuki cross-coupling reactions and resulted in very good yields. These compounds are precursors of new porphyrin architectures able to coordinate two metals: one in the porphyrin core and the second around the pyridyl moiety. During the coupling reactions, a higher reactivity of a chloro picolyl group was evidenced compared to a bromo function on the same reacting molecule.

2-Methyltetrahydrofuran: A Green Solvent for Iron-Catalyzed Cross-Coupling Reactions

2018

Iron‐catalyzed cross‐coupling reactions allow sustainable formation of C−C bonds using cost‐effective, earth‐abundant base‐metal catalysis for complex syntheses of pharmaceuticals, natural products, and fine chemicals. The major challenge to maintain full sustainability of the process is the identification of green and renewable solvents that can be harnessed to replace the conventional solvents for this highly attractive reaction. Herein, iron‐catalyzed cross‐coupling of aryl chlorides and tosylates with challenging organometallic reagents possessing β‐hydrogens is found to proceed in good to excellent yields with the green, sustainable, and eco‐friendly 2‐methyltetrahydrofuran (2‐MeTHF) a…

Light Induced C-C Coupling of 2-Chlorobenzazoles with Carbamates, Alcohols, and Ethers.

2016

A light induced, transition-metal-free C-C coupling reaction of 2-chlorobenzazoles with aliphatic carbamates, alcohols, and ethers is presented. Inexpensive reagents, namely sodium acetate, benzophenone, water, and acetonitrile, are employed in a simple reaction protocol using a cheap and widely available 25 W energy saving UV-A lamp at ambient temperature.

Histone macroH2A1.2 promotes metabolic health and leanness by inhibiting adipogenesis

2016

Background Obesity has tremendous impact on the health systems. Its epigenetic bases are unclear. MacroH2A1 is a variant of histone H2A, present in two alternatively exon-spliced isoforms macroH2A1.1 and macroH2A1.2, regulating cell plasticity and proliferation, during pluripotency and tumorigenesis. Their role in adipose tissue plasticity is unknown. Results Here, we show evidence that macroH2A1.1 protein levels in the visceral adipose tissue of obese humans positively correlate with BMI, while macroH2A1.2 is nearly absent. We thus introduced a constitutive GFP-tagged transgene for macroH2A1.2 in mice, and we characterized their metabolic health upon being fed a standard chow diet or a hig…