Rationalizing the Stereoelectronic Influence of Interglycosidic Bond Conformations on the Reactivity of 1,4-O-Linked Disaccharide Donors

Abstract

Disaccharide donors are key precursors in convergent glycan synthesis strategies. Unexpectedly, we observed that disaccharide thioglycosyl donors containing 1,4-O-linked α-glycosidic bonds are much more reactive than their β-analogues with the same protecting group pattern. Herein, we rationalized that such a difference in their reactivity is attributed to the conformation of the 1,4-O-interglycosidic bond which is controlled by anomeric and exo-anomeric effects. Moreover, the conformational preferences of these donors are dictated by the dihedral angles ϕ and ψ of their interglycosidic linkages and the torsional angle ω of their side chain along the C5–C6 bond. This fundamental research clarifies how the long-range stereoelectronic effects from the nonreducing end sugar can influence the reactivity of the leaving group at the reducing end and the behavior of disaccharide donors thereof.

Detection and Semi‐Quantification of Lipids on High‐Performance Thin‐Layer Chromatography Plate Using Ceric Ammonium Molybdate Staining

“…The most common ones include cupric sulfate, boric acid, [3,11] cupric acetate, [13] phosphomolybdic acid, [15] and 50% sulfuric acid. [11,14] CAM or Hanessian's staining has been extensively used for visualization of carbohydrates (polyhydroxylated compounds) [21,22] and carbonyl compounds. [23] The application of CAM staining for detection of lipids chemically synthesized or extracted from biological samples has been documented in the literature.…”