The effect of N-aglycones at C1’ on the drive of two-state north (N (C3’-endo-C2’-exo)) * south ( S (C2’endo-C3’-exo)) pseudorotational equilibrium in 8-D-ribofuranosyl-N-nucleosides consists of two counteracting contributions from (i) the anomeric effect (stereoelectronic interactions between furanose 04’ and the nucleobase nitrogen at Cl’), which places the aglycone in the pseudoaxial orienta...

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...

[2+2] Cycloadditions of methylene exo-glycal derivatives with chlorosulfonyl isocyanate and dichloroketene were studied in detail, investigating the effect carbohydrate moiety, protecting groups as well reaction temperature on yields transformations. These reactions gave new anomeric spiro-β-lactam spiro-cyclobutanone derivatives, whose structure was established by 1D 2D NMR MS experiments. The...

Condensation products of 5-substituted phenyl-2-furoyl hydrazide with different monosaccharides D-glucose, D-galactose, D-mannose, D-fucose and D-arabinose were prepared. The anomerization and cyclic-acyclic isomers were investigated by 1H NMR spectroscopy. The results showed that, except for the d-glucose derivatives, which were in the presence of β-anomeric forms, all derivatives were in an a...

The unusual stability of bis- and tris-peroxides contradicts the conventional wisdom - some of them can melt without decomposition at temperatures exceeding 100 °C. In this work, we disclose a stabilizing stereoelectronic effect that two peroxide groups can exert on each other. This stabilization originates from strong anomeric nO → σ*CO interactions that are absent in mono-peroxides but reintr...

Lewis acid mediated substitution reactions using [D]triethylsilane as a nucleophile at the anomeric center of the four pentofuranoses, ribose, arabinose, xylose, and lyxose, all proceed with good to excellent stereoselectivity to provide the 1,2-cis adducts. To unravel the stereoelectronic effects underlying the striking stereoselectivity in these reactions we have mapped the energy landscapes ...

Spatial orientation of carbohydrates is a meaningful parameter in carbohydrate recognition processes. To vary orientation of sugars with temporal and spatial resolution, photosensitive glycoconjugates with favorable photochromic properties appear to be opportune. Here, a series of azobenzene glycosides were synthesized, employing glycoside synthesis and Mills reaction, to allow "switching" of c...

The subject paper presented the ®rst confor-mational analysis of the anomeric e€ect within the context of molecular orbital theory, discussed the utility of Fourier decomposition of a torsional coordinate as a method for analyzing disparate electronic in¯uences on that coordinate, and helped settle debate on the nature of anomeric stabilization. Sugars are the stepchildren of the biomonomer fam...