Fucoside

The latter was isolated in the form of fully methylated methyl fuco-side, i. e., methyl 2,3,4-trimethyl-a-L-fucoside (XLVII), a compound previously obtained from methylated gum tragacanth.128 The recognition of this particular derivative indicates that the n-fucose residues in part at least must constitute end groups linked glycosidically to the rest of the molecule. The same compound128 was isolated by methylation and... 

Fig. 72. AB2-based polyazides used in click chemistry with propargylated p-D-galactosides and a-L-fucosides.427...

A useful extension of the in situ anomerization process involves the employment of C-nucleophiles such as vinyl and allyl magnesium bromides. Grignard reactions to per-O-benzylated glycosyl iodides proceed stereoselectively when a strong nucleophile like allyl magnesium bromide is used, giving [1-C-allyl fucosides (95% P-only)... 

This enzyme [EC 3.2.1.51] catalyzes the release of alcohols from o -L-fucosides to yield o -L-fucose. 

This enzyme [EC 3.2.1.22] catalyzes the hydrolysis of melibiose to yield galactose and glucose. It will also act on terminal, nonreducing a-D-galactose residues in a-D-galactosides. In addition, it will hydrolyze a-D-fucosides. 

Deguise I, Lagnoux D, Roy R. Synthesis of glycodendrimers containing both fucoside and galactose residues and their binding properties to Pa-IL and PA-IIL lectins from... 

To a stirred suspension of Sn(OTf)2 (12.5mg, 0.03mmol), TMSOTf (37.2mg. 0.3mmol), and 3-A molecular sieves (5 mg) in toluene/CH2Cl2 (3 1 3mL) was successively added 2,3,4-tri-O-benzyl-L-fuco-pyranosyl methoxyacetate (50.7mg, 0.1 mmol) and the amino acid derivative (1.3 equiv) in CH2C12 (1.5 mL) at rt. The mixture was stirred for 20 h at rt, then quenched by adding sat. NaHC03. After workup and purification with preparative TLC (silica gel), the desired fucoside was isolated yield 98%. The ratio of anomers was determined by HPLC analysis. 

Mareck, U. et al., The 6-C-chinovoside and 6-C-fucoside of luteolin from Passiflora edulis. Phytochemistry, 30, 3486, 1991. 

The efficiency and chemoselectivity of this method was demonstrated in syntheses of glycopeptides that contain the biologically important, but rather sensitive fucoside linkage [19,26-28],... 

Conchie and Percival97 found that the direct methylation of fucoidin with dimethyl sulfate and sodium hydroxide was more satisfactory than the simultaneous deacetylation and methylation of its acetyl derivative. Methylated fucoidin was hydrolyzed and the products were converted to their methyl glycosides. By chromatography on alumina there were isolated methyl L-fucosides (about 20%), methyl 3-methyl-L-fucosides (57%) and methyl 2,3-dimethyl-L-fucosides (20%). 

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