نتایج جستجو برای: anomeric effect
تعداد نتایج: 1642348 فیلتر نتایج به سال:
meysam yarie was born in 1987 in malayer/ hamedan, iran. he received his b.sc. in applied chemistry (2010) from malek-ashtar university of technology and m.sc. in organic chemistry (2012) from kurdistan university under the supervision of dr. kamal amani. he is currently working towards his ph.d. under the supervision of professor mohammad ali zolfigol. his research interest is the synthesis, c...
In this theory study the dominance of non-classical 1,3-diaxial CHax⋯OC hydrogen bonds (NCHBs) dictating anomeric effects in fluorinated methoxycyclohexanes and 2-methoxytetrahydropyrans is demonstrated, a phenomenon which most often described as consequence hyperconjugation.
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...
The HF/6-31G level of theory was used to calculate relaxed potential energy surfaces for 12 analogs of disaccharides. The analogs were made by replacing glucose with tetrahydropyran and fructose with 2-methyltetrahydrofuran. Molecules had zero, one or two anomeric carbon atoms, and di-axial, axial-equatorial, and di-equatorial linkages. Despite the absence of hydroxyl groups, the surfaces accou...
The bioactive amino monosaccharide D-glucosamine has been generated in the gas phase via laser ablation of D-glucosamine hydrochloride. Three cyclic α-(4)C1 pyranose forms have been identified using Fourier transform microwave techniques. Stereoelectronic hyperconjugative forces - essentially linked with the anomeric or gauche effect - and cooperative OH···O, OH···N and NH···O chains, extended ...
Ether-protecting functions at C-2 hydroxy groups have been found to play participating roles in glycosylations when the reactions are conducted in nitrile solvent mixtures. The participation mechanism is based on intramolecular interaction between the lone electron pair of the oxygen atom of the C-2 ether function and the nitrile molecule when they are positioned in a cis configuration. A 1,2-c...
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