Glycosylation-solid phase

Trialkylsilane resin (PS-DES) 50 was incorporated for solid-phase glycosylation by anchoring a glycosyl donor via their corresponding thio-phenyl ether or 3-glucopyranosyl fluorides (Scheme 20) [59]. Disaccharides... 

Urge, L., Otvos Jr., L., Lang, E., Wroblewski, K., Laczko, I., and Hollosi, M. (1992) Fmoc-protected, glycosylated asparagines potentially useful as reagents in the solid-phase synthesis of N-glycopeptides. Carbohydr. Res. 235, 83-93. 

The solid-phase synthesis of glycopeptides was first realized by applying the polymeric benzyl ester principle of Merrifield. According to this methodology, Lavielle and associates (50) used 7V-(tm-butyloxycarbonyl)-<9-glycosyl serine derivative 153 for condensation with resin-linked alanine 154. 

All the described solid-phase glycosylation protocols required long reaction times to proceed in reasonable yields because of the slower reaction kinetics on support than in solution. Furthermore, since no analytical means were available to monitor the progress of the reaction on the bead, development of optimal reaction conditions was difficult. The approach described by Guthrie and coworkers in the early 1970s for... 

High selectivity and substrate specificity of glycosyl transferases make them valuable catalysts for special linkages in polymer-supported synthesis. There is, however, still a rather limited set of enzymes available to date, and the need to synthesize a variety of natural and non-natural oligosaccharides prevails. Particularly with regard to combinatorial approaches, chemical solid-phase oligosaccharide synthesis promises to meet the demands most effectively. 

The H-type 2 determinant (Scheme 2.9) is found largely on the surface of erythrocytes and the epidermis of type O persons, at the termini of membrane associated glycoproteins.18 Persons of blood types A and B also possess this determinant, which is further glycosylated at its galactose nonreducing terminus with a galactosamine (type A) or galactose moiety (type B). The solid phase assembly of... 

The first problem to be addressed in the solid-phase assembly of Leb involved the synthesis of the core tetrasaccharide (Scheme 2.17).25 Polymer-bound galactal 10 was epoxidized with DMDO. The resultant epoxide reacted with a solution of glucal 55 to give polymer-bound disaccharide diol 56. This reaction proceeded in a highly regioselective fashion, wherein glycosylation occurred only at the allylic C3 position... 

The Sulfoxide Glycosylation Method and its Application to Solid-Phase Oligosaccharide Synthesis and the Generation of Combinatorial Libraries... 

The mild conditions employed for the activation of sulfoxides, and the high reactivity of the glycosyl donor, suggested that the method might translate well to the solid phase. Moreover, the nonpolar nature of the sulfoxide, triflic anhydride, and DTBMP (solution-based reagents) should enable them to partition effectively into a non-polar, polystyrene-based resin. 

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