187746-20-9Relevant academic research and scientific papers
Synthesis of α- and β-linked tyvelose epitopes of the Trichinella spiralis glycan: 2-Acetamido-2-deoxy-3-O-(3,6-dideoxy-D- arabinohexopyranosyl)-β-D-galactopyranosides
Probert, Mark A.,Zhang, Jian,Bundle, David R.
, p. 149 - 170 (2007/10/03)
The anomeric configuration of tyvelose, 3,6-dideoxy-D-arabino-hexopyranose, in the recently discovered glycan epitopes of the parasite Trichinella spiralis has not been established. Two 2-(trimethylsilyl)ethyl disaccharide glycosides, α- and β-Tyv-(1 → 3)-β-D-GalNAc (4 and 5) have been synthesized to provide model compounds that, together with the methyl 3,6-dideoxy-α-and β-D-arabino-hexopyranosides (2 and 3), aid the determination of the anomeric configuration of tyvelose residues in the parasite glycan, either indirectly by immunochemical inhibition data or directly by the technique of 1H NMR spectroscopy. Methyl 3,6-dideoxy-β-D-arabinohexopyranoside (3) was synthesized from methyl 2,3-anhydro-4,6-O-benzylidene-β-D- mannopyranoside (9) by a method previously used for the α anomer 2. Benzylation of 2 provided a route to the glycosyl donor, 2,4-di-O-benzyl-3,6-dideoxy-α- D-arabino -hexopyranosyl chloride (30), that reacted with the selectively protected 2-acetamido-2-deoxy-D-galactopyranoside alcohol 18 in the presence of an insoluble silver zeolite catalyst to give the α- and β-linked disaccharides 31 and 32. Glycosylation of the related 2-acetamido-2-deoxy-D-galactopyranoside alcohol 27 by 30 under similar conditions provided disaccharides 33 and 34 containing a tether. Deprotection of the saccharide and derivatization of the tether with 1,2-diaminoethane provided amide derivatives 35 and 36 suitable for the preparation of neoglycoconjugate antigens. Complete 1H and 13C NMR chemical shifts of the deprotected disaccharides and monosaccharides are reported.
Synthesis and conformational studies of the tyvelose capped, Lewis-x like tetrasaccharide epitope of Trichinella spiralis
Zhang, Jian,Otter, Albin,Bundle, David R.
, p. 1989 - 2001 (2007/10/03)
Chemical synthesis and high resolution NMR studies are reported for the tetrasaccharide epitope and constituent structures that occur as terminal elements of Trichinella spiralis cell surface glycans. The 2-(trimethylsilyl)ethyl and methyl glycosides of Lewis-x type trisaccharides, in which βGalNAc replaces βGal were synthesized from monosaccharide synthons utilizing thioglycoside and halide-ion glycosylation methods. The unique 3,6-dideoxy-β-D-arabinohexopyranosyl residue that caps the structure was introduced to selectively protected 2-(trimethylsilyl)ethyl and methyl trisaccharide glycosides by utilizing an insoluble silver zeolite catalyst and a glycosyl halide. In separate reactions not only were the principal targets obtained but also the corresponding α-linked tetrasaccharides. A comparison of the NMR spectra of the methyl tetrasaccharide glycosides showed that at the site of the α-linked tyvelose structure, specific GalNAc resonances (C-1, C-2, C-3) possess uncharacteristically wide 13C (8-21 Hz) and 1H lines. The β-linked tetrasaccharide glycoside, that represents the native parasite epitope, exhibited only narrow line widths (3 Hz, 13C). Since NOE derived distance constraints for the α-linked tyvelose structure were not consistent with the existence of unusual glycosidic conformers, the origin of the limited number of wide lines was attributed to local rigidity in the GalNAc residue, at the site of tyvelose glycosylation.
