نتایج جستجو برای: chiral compounds
تعداد نتایج: 262114 فیلتر نتایج به سال:
A series of chiral diphosphine ligands denoted as PQ-Phos was prepared by atropdiastereoselective Ullmann coupling and ring-closure reactions. The Ullmann coupling reaction of the biaryl diphosphine dioxides is featured by highly efficient central-to-axial chirality transfer with diastereomeric excess >99%. This substrate-directed diastereomeric biaryl coupling reaction is unprecedented for the...
Two pairs of enantiomerically pure three-dimensional (3D) chiral polyoxometalate (POM) framework materials l,d-[K(H2O)]6·[H2GeW12O40]3·35H2O (1a and 1b) and l,d-[K(H2O)]6·[H2SiW12O40]3·29H2O (2a and 2b) based on inorganic achiral building blocks, have been synthesized and characterized by X-ray crystallography, elemental analysis, powder X-ray diffraction (PXRD), UV-Vis spectroscopy, circular d...
One of the most attractive hypothesis for the origin of homochirality in terrestrial bioorganic compounds is that a kind of "chiral impulse" as an asymmetric excitation source induced asymmetric reactions on the surfaces of such materials such as meteorites or interstellar dusts prior to the existence of terrestrial life (Cosmic Scenario). To experimentally introduce chiral structure into racem...
We study the D → σπ, D → ρπ, B− → σπ−, B− → ρ0π− and B̄ → ρ±π∓ decays in a valence quark triangle model, incorporating chiral symmetries. We find a good agreement with recent experimental data for D → σπ and for D → ρπ. We point out that a long-distance contribution due to the axial vector a1 meson pole, calculated by using chiral symmetry, can be relevant to explain D → ρπ and for lowering the ...
H ighlighting this issue of PNAS and the forthcoming one* is a Special Feature comprising 8 Perspectives and 44 research articles that cover aspects of asymmetric catalysis, the phenomenon whereby a chiral catalyst promotes the conversion of an achiral substrate to a chiral product with a preference for the formation of one of the mirror image isomers (enantiomers). The demand for chiral compou...
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