نتایج جستجو برای: chiral extraction
تعداد نتایج: 202657 فیلتر نتایج به سال:
The stereoselective toxicokinetics of ethofumesate enantiomers following a single intravenous (i.v.) administration at doses of 30 mg/kg were investigated in rabbits. Plasma concentrations of (+)- and (-)-ethofumesate were analyzed by a validated chiral HPLC method that involved extraction of plasma with organic solvent followed by separation on a cellulose-Tris-(3,5-dimethylphenylcarbamate)-ba...
We present technical details of the evaluation of the elastic ππ scattering amplitude to two loops in chiral perturbation theory. In particular, we elaborate on the renormalization procedure at the two–loop order and on the evaluation of the relevant Feynman diagrams that can all be expressed in terms of elementary functions. For the sake of clarity, we discuss these matters both in the N–compo...
We present a complete calculation of the Kl3 decays K + → πlνl and K → πlνl to O(p4, (md −mu)p, ep) in chiral perturbation theory with virtual photons and leptons. We introduce the concept of generalized form factors and kinematical densities in the presence of electromagnetism, and propose a possible treatment of the real photon emission in K l3 decays. We illustrate our results by applying th...
We present a quenched lattice study of the form factors f + (q 2) and f 0 (q 2) of the matrix elements π|¯ sγ µ u|K. We focus on the second-order SU(3)-breaking quantity [1 − f + (0)], which is necessary to extract |V us | from K ℓ3 decays. For this quantity we show that it is possible to reach the percent precision which is the required one for a significant determination of |V us |. The leadi...
We report on a recent study of the SU(3)-breaking corrections to the hyperon vector coupling f1(0) up to O(p4) in covariant baryon chiral perturbation theory with dynamical octet and decuplet contributions. The decuplet contributions are taken into account for the first time in a covariant ChPT study and are found of similar or even larger size than the octet ones. We predict positive SU(3)-bre...
Chiral hexaazamacrocycles with a trianglamine structure and C(3)-symmetry, containing six ring substituents and twelve stereocenters have been tested as chiral solvating agents (CSAs) for α-substituted carboxylic acids. Excellent results have been obtained with a hexaphenyl-substituted macrocycle. The optimal ratio between the macrocycle and racemic acid, allowing for baseline separation of the...
An efficient one-pot three-component procedure for the synthesis of new chiral spiro-oxindolopyrrolizidines with highly regio-, diastereo-, and enantioselective from 1,3-dipolar cycloaddition of azomethine ylides and optically pure active cinamoyl oxazolidinone are described. The process occurs at room temperature in aqueous ethanol as green solvent and in the absence of any bidentate chelating...
A simple, rapid and sensitive chiral capillary zone electrophoresis coupled with acetonitrile-field-amplified sample stacking method was developed that allows the simultaneous enantioselective separation of the mirtazapine, N-demethylmirtazapine, 8-hydroxymirtazapine and mirtazapine-N-oxide. The separation was achieved on an uncoated 40.2 cm×75 μM fused silica capillary with an applied voltage ...
trifluoromethylated organic compounds, especially chiral quaternary alcohols bearing trifluoromethyl group are of important intermediates in drugs, agrochemicals and etc.an efficient epoxidation of β-cf3-β,β-disubstituted unsaturated ketones (6) has been developed with environmental benign hydrogen peroxide as the oxidant and f5-substituted chiral quaternary ammonium salt (1g or 5) derived from...
(-)-Gephyrotoxin-223 was formally synthesized from chiral synthon 1 which has been chemoenzymatically synthesized in the presence of Candida Antartica lipase.
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