Structure of the tetrasaccharide analog related to the repeating unit of the <i>O</i>-specific lipopolysaccharide of <i>Escherichia coli</i> O75.

<p>Structure of the tetrasaccharide analog related to the repeating unit of the <i>O</i>-specific lipopolysaccharide of <i>Escherichia coli</i> O75.</p

Tetrasaccharide repeating unit corresponding to the <i>O</i>-specific lipopolysaccharide of <i>Escherichia coli</i> O75.

<p>Tetrasaccharide repeating unit corresponding to the <i>O</i>-specific lipopolysaccharide of <i>Escherichia coli</i> O75.</p

Palladium-Catalyzed α‑Stereoselective <i>O</i>‑Glycosylation of O(3)‑Acylated Glycals

Pd­(MeCN)₂Cl₂ enables the α-stereoselective catalytic synthesis of 2,3-unsaturated <i>O</i>-glycosides from O(3)-acylated glycals without the requirement for additives to preactivate either donor or nucleophile. Mechanistic studies suggest that, unlike traditional (η3-allyl)­palladium-mediated processes, the reaction proceeds via an alkoxy-palladium intermediate that increases the proton acidity and oxygen nucleophilicity of the alcohol. The method is exemplified with the synthesis of a range of glycosides and glycoconjugates of synthetic utility

Structure of the tetrasaccharide repeating unit corresponding to the <i>O</i>-specific lipopolysaccharide of <i>Escherichia coli</i> O75.

<p>Structure of the tetrasaccharide repeating unit corresponding to the <i>O</i>-specific lipopolysaccharide of <i>Escherichia coli</i> O75.</p

Gold(I)-Catalyzed Direct Stereoselective Synthesis of Deoxyglycosides from Glycals

Au­(I) in combination with AgOTf enables the unprecedented direct and α-stereoselective catalytic synthesis of deoxyglycosides from glycals. Mechanistic investigations suggest that the reaction proceeds via Au­(I)-catalyzed hydrofunctionalization of the enol ether glycoside. The room temperature reaction is high yielding and amenable to a wide range of glycal donors and OH nucleophiles

Thermal, Spectroscopic, and Crystallographic Analysis of Mannose-Derived Linear Polyols

The major diastereomer formed in the Barbier-type metal-mediated allylation of d-mannose has previously been shown to adopt a perfectly linear conformation, both in solid state and in solution, resulting in the formation of hydrogen-bonded networks and subsequent aggregation from aqueous solution upon stirring. Here, a comprehensive study of the solid state structure of both the allylated d-mannose and its racemic form has been conducted. The binary melting point diagram of the system was determined by differential scanning calorimetry analysis, and the obtained results, along with structure determination by single crystal X-ray diffraction, confirmed that allylated mannose forms a true racemate. Further examination by powder X-ray diffraction and CP MAS ¹³C NMR spectroscopy revealed polymorphism both in the pure enantiomer and in the racemate. In addition, the propargylated and hydrogenated analogues of allylated d-mannose were prepared and subjected to thermal and spectroscopic analyses. The crystal structure of the propargylated compound was successfully determined, showing a linear molecular conformation similar to that found for allylated d-mannose. Both new compounds likewise display aggregation behavior in water, further verifying that the low-energy linear conformation plays a significant role in this unusual behavior of these rodlike mannose derivatives