نتایج جستجو برای: anomeric effects
تعداد نتایج: 1544976 فیلتر نتایج به سال:
A method for the investigation of the influence of protecting groups on the anomeric equilibrium in the sialic acid glycosides has been developed on the basis of the equilibration of O-sialyl hydroxylamines by reversible homolytic scission of the glycosidic bond following the dictates of the Fischer-Ingold persistent radical effect. It is found that a trans-fused 4O,5N-oxazolidinone group stabi...
Ab initio HF/6-31G* Methode was employed to calculate the bond length in 2- phosphinanes when electronegative groups was at C-2 tend axial and equatorial positions. The magnitude of the anomeric effect depends on the nature of the substituent, the effect of the substituent can be seen by comparing the bond length in 2-chloro and 2- boromo substituented phosphinanes. The effect of anomeric effec...
Ab initio HF/6-31G* Methode was employed to calculate the bond length in 2- phosphinanes when electronegative groups was at C-2 tend axial and equatorial positions. The magnitude of the anomeric effect depends on the nature of the substituent, the effect of the substituent can be seen by comparing the bond length in 2-chloro and 2-boromo substituented phosphinanes. The effect of anomeric eff...
NBO analysis, hybrid density functional theory (B3LYP/6-311+G**) and ab initio molecular orbital (HF/6-311+G**) based methods were used to study the anomeric effects (AE), electrostatic interactions, dipole-dipole interactions and steric repulsion effects on the conformational properties of 2-methoxy- (1), 2-methylthio- (2), 2-methylseleno- (3), 2-fluoro- (4), 2-chloro- (5) and 2-bromocyclohexa...
Uronic acids are carbohydrates present in relevant biologically active compounds. Most of the latter are glycosides or oligosaccharides linked by their anomeric carbon, so their synthesis requires glycoside-bond formation. The activation of this anomeric center remains difficult due to the presence of the electron-withdrawing C-5 carboxylic group. Herein we present an overview of glucuronidatio...
Retraction of ‘[TEATNM] and [TEATCM] as novel catalysts for the synthesis pyridine-3,5-dicarbonitriles via anomeric-based oxidation’ by Saeed Baghery et al. , New J. Chem. 2017, 41 9276–9290, https://doi.org/10.1039/C7NJ01934C.
Heparin and low molecular weight heparins are polydisperse polysaccharides with a degree of polymerization ranging from 4 to approximately 40. The determination of their average molecular weights has traditionally relied on size exclusion chromatography involving the use of oligosaccharides of known size and molecular weight as standards. 13C NMR spectroscopy is applied for the first time to ob...
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