SYNTHESIS, NMR, AND CONFORMATIONAL STUDIES OF FUCOIDAN FRAGMENTS. III. EFFECT OF BENZOYL GROUP AT O-3 ON STEREOSELECTIVITY OF GLYCOSYLATION BY 3-O- AND 3,4-DI-O-BENZOYLATED 2-O-BENZYLFUCOSYL BROMIDES

Abstract

The effect of a benzoyl group at O-3 on stereoselectivity of glycosylation by 3-O-and 3,4-di-O-benzoylated 2-O-benzyl-L-fucopyranosyl bromides was studied by direct chemical experiments and computational chemistry. The influence of a benzoyl group at O-3 of the fucosyl donors was shown to have a larger effect on the efficiency of ␣-fucosylation than a benzoyl group at O-4. It is hypothesized that this is a result of the ability of a benzoyl group at O-3 to participate in glycosyl cation stabilization.

Ultrastructure of acidic polysaccharides from the cell walls of brown algae

“…(B) Agarose gel electrophoresis of the crude polysaccharide (1) and the purified sulfated fucan (2) ($15 lg of each) were applied to a 0.5% agarose gel and the electrophoresis was run and stained as described (Pereira et al, 1999) physiological role of these molecules depends exclusively of the overall negative charged groups. Only very recent studies using synthetic oligosaccharides have suggested that sulfated fucans may assume specific conformation (Gerbst et al, 2001(Gerbst et al, , 2002.…”

Synthesis and Biological Evaluation of Fucoidan-Mimetic Glycopolymers through Cyanoxyl-Mediated Free-Radical Polymerization

“…17 The Nifantiev group has presented extensive work synthesizing di-, tri-, tetra-, hexa-, octa-, dodeca-and hexadecafucosides with various differences in branching-, sulfation-and fucosidic linkage patterns. [18][19][20][21][22][23][24][25] These fucoidan fragments were subjected to extensive conformational studies through NMR, [18][19][20][21][22][23]25 yet no biological activity studies have been published. We also noted that all the synthetic fucoidan fragments referred to were produced through saccharide formation, which is often time-consuming and results in poor yields with growing saccharide chain length.…”

Acid-promoted synthesis of per-O-sulfated fucooligosaccharides related to fucoidan fragments

“…[3][4][5][6] To determine the structure of pharmacophore fragments within the fucoidan chains, we carried out the systematic synthesis 1,7-12 (see Ref. 13 for review), conformational analysis, 8,[10][11][12][14][15][16] and studies of biological activities of various oligofucosides related to natural fucoidans.…”