نتایج جستجو برای: anomeric effects
تعداد نتایج: 1544976 فیلتر نتایج به سال:
Anomeric O-alkylation/arylation is applied to the synthesis of 2-deoxy-beta-glycosides. Treatment of lactols with NaH in dioxane followed by the addition of electrophiles leads to the formation of 2-deoxy-beta-glycosides in high yield and high selectivity. The high beta-selectivity observed here demonstrates a powerful stereoelectronic effect for the stereoselective formation of acetals under k...
Quantum chemical analysis shows aza-graphane isomers, with alternate C-H and N: sites as ideal organocatalysts; their kinetic stability arises from the tertiary orthoamide. DFT calculations give split-off bands originating from nitrogen lone-pairs with substantial mixing of hydrogen, indicating an optimal balance between nitrogen basicity and C-H activation through the anomeric effect.
The O-allylphenyl (AP) anomeric moiety was investigated as a new leaving group that can be activated for chemical glycosylation under a variety of conditions, through both direct and remote pathways. Differentiation between the two activation pathways was achieved in a mechanistic study. The orthogonal-type activation of the AP moiety along with common thioglycosides allows for the execution of...
4,6-O-Ethylidene-N-(2-hydroxybenzylidene)-D-glucopyranosylamine was synthesized and characterized using analytical, spectral and single-crystal X-ray diffraction methods. The anomeric nature of the saccharide moiety was proposed based on H NMR studies and was confirmed by the crystal structure. The lattice structure of this compound was compared with that of its analogues.
A tetrasaccharide repeating unit corresponding to the cell-wall lipopolysaccharide of E. coli O40 was synthesized by using a convergent block glycosylation strategy. A disaccharide donor was coupled to a disaccharide acceptor by a stereoselective glycosylation. A 2-aminoethyl linker was chosen as the anomeric protecting group at the reducing end of the tetrasaccharide. All glycosylation steps a...
The preparation of one isomer of each of the 16 enantiomeric pairs of the aldohexofuranose pentaacetates is described together with (1)H and (13)C NMR data. Eight of the isomers have been obtained crystalline. Equilibrium values for the anomeric pairs have been determined.
Cause and effect: In science, language is often subordinated to empirical data, but words can influence our ability to understand and communicate science. This Essay argues that imprecise language has confounded studies that probe the interactions underlying the anomeric effect and related phenomena.
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