نتایج جستجو برای: hydrogen atom transfer
تعداد نتایج: 464074 فیلتر نتایج به سال:
Light?Driven Enantioselective Synthesis of Pyrroline Derivatives by a Radical/Polar Cascade Reaction
Herein, a light-driven, atom-economical process that provides access to enantiomerically enriched substituted chiral 1-pyrroline derivatives is introduced. The strategy involves the distal functionalization of acyl heterocycles through hydrogen-atom transfer (HAT) and use tailor-made ketimines as reliable electrophilic partners. This transformation translated into an controlled radical/polar ca...
In the present study we have analyzed hydrogen bonding in dimer and trimer of oxalic acid, based on a recently proposed charge and energy decomposition scheme (ETS-NOCV). In the case of a dimer, two conformations, α and β, were considered. The deformation density contributions originating from NOCV's revealed that the formation of hydrogen bonding is associated with the electronic charge deform...
exfoliated poly (chloromethyl styrene-co-styrene)-g-polyacrylonitryle/organo- modified montmorillonite [p(cmst-co-st)-g-pan/o-mmt] nanocomposite was synthesized through solution intercalation method by using atom transfer and nitroxide mediated radical polymerization. at first, poly (chloromethyl styrene-costyrene) copolymer was synthesized by nitroxide - mediated “living” free radical polyme...
Absolute rate constants for the reaction of NADH with thiyl free radicals derived from various sulphur-containing compounds of biological significance were measured by using the technique of pulse radiolysis. These and related reactions with phenoxyl free radicals are believed to occur through one-electron-transfer processes. Further evidence comes from studies with deuterated NADH. The results...
Recent studies on cholesterol biosynthesis have demonstrated that the biosynthesis of squalene from its immediate precursor, farnesyl pyrophosphate, is accompanied by the exchange of 1 hydrogen atom at C-l, in 1 of the 2 precursor molecules, for a hydride ion derived from reduced triphosphopyridine nucleotide (l-3). Thus, Popjak et al. obsrrved that the farnesol of farnesyl pyrophosphate biosyn...
Abstract A concise total synthesis of (+)-aphanorphine is described. The key features the strategy include a Pd-catalyzed intermolecular trimethylenemethane [3+2]-cycloaddition to form ring C and Co-catalyzed radical cyclization through hydrogen-atom transfer close B. was completed in six steps.
The role of spin polarization on adsorption of atomic and molecular hydrogen on Si(111)(1× 1) surface is examined by comparing the results of the local spin density approximation (LSD) and those of the local density approximation (LDA). A large improvement of the adsorption energies (around 0.8 eV/H) was found for the H atom adsorbed on Si(111)(1× 1) surface. The inclusion of spin polarization ...
The spatial volume occupied by an atom depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent algorithms and packages to calculate it numerically for other materials. Three-dimensional visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. In this ...
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