Lewis hexasaccharide

Lewis hexasaccharide and Le -Le nonasaccharide are tumor markers that are ciu rently being evaluated as cancer vaccines [49]. Their complex struc-tmes constitute a challenge for synthesis both in solution and on soUd phase [50,51]. The successful automation [19] of this synthesis came after a solution phase [52] study and some modification to the previous automated syntheses (Scheme 14). 

Jain, R. K. Matta, K. L., Chemical synthesis of a hexasaccharide comprising the Lewis(x) determinant linked beta-(l->6) to a linear trimannosyl core and the precursor pentasaccharide lacking fucose. Carbohydr. Res. 1996,282, 101-111. 

Synthesis of a Hexasaccharide by Formation of the GlcNf -3)Gat Glycoside Bond Intermediate in the Synthesis of Lewis X-Antigens (Le ) [30bI... 

Further sialylation give a sialyl Lewis x-containing hexasaccharide [77]. 

Nilsson, M, Norberg, T, Synthesis of carbohydrate derivatives corresponding to a tumor-associated glycolipid a trimeric Lewis nonasaccharide and a trimeric A-acetyl lactosamine hexasaccharide, J. Carbohydr. Chem., 8, 613-627, 1989. 

Oligosaccharide synthesis with tri-chloroacetimidates] general aspects, 290 glycopeptide, 306 glycosyl phosphates, 294, 307, 308 hexasaccharide, 299 inverse procedure, 294 kinetic, thermodynamic effects, 293 Lewis acid catalysis, 289 neighboring group participation,... 

SCHEME 55. Solid-phase synthesis of dimeric Lewis X hexasaccharide 274.247... 

Scheme 11.2-1 Retrosynthesis of the building blocks 4-8. Bn - benzyl, protected Lewis X pentasaccharide 1, Lewis Bu - butyl, Fmoc - 9-fluorenylmethoxy-hexasaccharide 2, and Le -Le 1 carbonyl, Lev - levulinoyl, Piv - pivaloyl,...

Cleavage of the ester linker from the resin using a solution of sodium methanolate over a period of 6 h provided the crude oligosaccharides. HPLC purification produced the fully protected Lewis X pentasaccharide 1, Lewis Y hexasaccharide 2, and Ley-Lex nonasaccharide 3 in 12.6, 9.9, and 6.5% yields, respectively [13]. 

Figure 3 A) Repeating hexasaccharide subunit of the capsular polysaccharide of V. cholerae 0139. Colitose is 3,6 di-deoxy-L-galactose. QuiNAc, N-Acetyl quinovosamine is 6-deoxy N-Acetyl glucosamine. B) The Lewis tetrasaccharide epitope. C) The repeating heptasaccharide subunit of the cell wall polysaccharide of S. mitis J22...

Coupling reaction of an a-(2 3)sialyl-galactose donor and a tetrasaccharide acceptor to afford the sialyl Lewis X hexasaccharide [38a]. 

Among the numerous complex polysaccharides that have been synthesized in the laboratory is the Lewis Y hexasaccharide, a tumor marker that is currently being explored as a potential cancer vaccine. 

Chitohexaose and hexa-M-acetylchitohexaose have been reported to have in vivo antitumour activity. " Two reports have appeared on the synthesis of the dimeric Lewis X hexasaccharide corresponding to part of a tumour-associated glycolipid (8). ... 

Branched Hexasaccharides.—Hasegawa s group have synthesized the tumour-associated ganglioside sialyl Lewis X (16) [cf. 15], - ... 

The structures of three new disialylfucosyl hexasaccharides, two new nona-saccharides, and a pentasaccharide isolated from human milk have been elucidated. The structures indicate that, in contrast to those of the ABO and Lewis blood-groups, the H determinant is located only on the type-I carbohydrate chain of the branched moiety. Extraction of bovine milk-fat globule membranes with phenol afforded three glycoproteins, which released the T antigen on treatment with alkaline borohydride and desialylation. ... 

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