Armed and disarmed n-pentenyl glycosides in saccharide couplings leading to oligosaccharides

Mootoo, David R.; Konradsson, Peter; Udodong, Uko E.; Fraser‐Reid, Bert

doi:10.1021/ja00224a060

Cited by 597 publications

(315 citation statements)

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“…Although this direct method enables us to access an isolable sulfonium ion 24 from a stable thioglycoside 23, the "superdisarmed" glycosyl donor, which has 2-O-benzyl, 3,4,6-tri-O-benzoyl protecting groups, is crucial. The concept of "armed-disarmed" glycosyl donors was proposed by Fraser-Reid and co-workers (22). The "superdisarmed" donor is less reactive than the typical "disarmed" donor, which has 2,3,4,6-tetra-O-benzoyl protecting groups, because the 3,4,6-O-tribenzoyl work as electron-withdrawing groups and the 2-O-benzyl group does not work as a neighboring group (23).…”

Section: B Preparation Of Glycosyl Sulfonium Ionsmentioning

confidence: 99%

Sulfonium Ions as Reactive Glycosylation Intermediates

Nokami

2012

TIGG

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Glycosyl sulfonium ions are positively charged organosulfur compounds having the positive charge on a sulfur atom that is covalently attached to the anomeric carbon. These species have received attention because of their potential as glycosylation intermediates. Recently, novel methods for the preparation of glycosyl sulfonium ions have been reported. The reactivity of glycosyl sulfonium ions can be controlled by changing the substituents on the sulfur atom and the protecting groups of the hydroxyl groups. Recent studies have also shown that glycosyl sulfonium ions are unique glycosylation intermediates that have modifiable reactivity.

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Section: B Preparation Of Glycosyl Sulfonium Ionsmentioning

confidence: 99%

Sulfonium Ions as Reactive Glycosylation Intermediates

Nokami

2012

TIGG

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“…Since the former was "disarmed" and the latter was "armed," 40,41) the combination seemed to be one of the most undesired ones; however, the reaction occurred to provide the desired disaccharide 3a in 87% yield (Chart 3). Similarly, in the case of donor 1d and acceptor 2, the reaction smoothly proceeded and gave the disaccharides 3n in good yield.…”

mentioning

confidence: 99%

Glycosylation Reaction of <i>Thioglycosides</i> by Using Hypervalent Iodine(III) Reagent as an Excellent Promoter

Kajimoto

Ogawa

Dohi

et al. 2016

CHEMICAL & PHARMACEUTICAL BULLETIN

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Thioglycosides are available donors in glycosylation due to the stability of the anomeric C-S bond under general reaction conditions of protection and deprotection, and offer orthogonality in their activation. We report now that the hypervalent iodine effectively induced glycosylation reaction of thioglycosides with various alcohols. This method features a high efficiency, completion in a short time, and proceeding under very mild conditions.

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“…However, the synthesis of complex carbohydrate ligands and analogs often requires many time-consuming, low-yielding steps. Chemical synthesis of oligosaccharides requires sophisticated strategies for protecting/deprotecting and assembling sugar monomers and for controlling product regiochemistry and stereochemistry (8)(9)(10). Enzymatic synthesis using glycosyltransferases has emerged as a useful alternative to chemical synthesis (11,12).…”

mentioning

confidence: 99%

Peptide ligands for a sugar-binding protein isolated from a random peptide library.

Oldenburg

Loganathan

Goldstein

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

249

119

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Peptide Carbohydrate-protein interactions form the basis of a host of biological processes (1, 2). For example, the periplasmic monosaccharide-binding proteins of Gram-negative bacteria serve as receptors for transport and chemotaxis (3), while cell-surface lectins mediate such processes as cell-cell adhesion (4, 5) and lymphocyte migration through lymphoid tissues (6). Carbohydrate recognition is central to the enzymatic synthesis and degradation of polysaccharides, glycoproteins, and glycolipids that play essential roles in metabolism and in the maintenance of cellular structures. Carbohydrate-protein associations are also critical in certain cycles of viral infection. For example, binding of the hemagglutinin protein of human influenza virus to sialic acid residues on erythrocyte cell-surface glycoproteins represents the initial step in influenza infection (7).Consequently, the development of potent inhibitors of carbohydrate-specific proteins may be of considerable importance in the generation of new therapeutic agents. However, the synthesis of complex carbohydrate ligands and analogs often requires many time-consuming, low-yielding steps. Chemical synthesis of oligosaccharides requires sophisticated strategies for protecting/deprotecting and assembling sugar monomers and for controlling product regiochemistry and stereochemistry (8-10). Enzymatic synthesis using glycosyltransferases has emerged as a useful alternative to chemical synthesis (11,12). However, this approach is limited by the availability of enzymes with the appropriate specificities.An alternative approach to the synthesis of polysaccharide ligands for carbohydrate-specific receptors is to ask whether peptides can be found that bind these proteins with high affinities. We describe a strategy for identifying novel peptide ligands for carbohydrate-binding proteins based on the screening of a large, highly diverse peptide library expressed on the surface of filamentous phage fd (13-16). The library consists of phage bearing random octapeptides fused to the amino terminus of the minor coat protein, pIII, and was screened by affinity purification on immobilized receptor. We chose as a model system the lectin Con A fromjack bean, whose physicochemical properties have been extensively studied (17). Con A is a tetramer composed of four identical polypeptide chains consisting of 237 residues each. Con A, which interacts preferentially with oligosaccharides bearing terminal a-linked mannose or glucose residues, is frequently employed in the purification and structural characterization of carbohydrates and glycoproteins and is also a lymphocyte mitogen. We report the isolation of peptide ligands for Con A that prevent binding of known monosaccharide ligands of the lectin and that inhibit Con A-dependent precipitation of polysaccharides. The prospect that specific ligands for carbohydrate-binding proteins can be assembled by coupling amino acid building blocks (rather than sugars) should greatly reduce the synthetic difficulties associated with i...

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Armed and disarmed n-pentenyl glycosides in saccharide couplings leading to oligosaccharides

Cited by 597 publications

References 0 publications

Sulfonium Ions as Reactive Glycosylation Intermediates

Sulfonium Ions as Reactive Glycosylation Intermediates

Glycosylation Reaction of <i>Thioglycosides</i> by Using Hypervalent Iodine(III) Reagent as an Excellent Promoter

Peptide ligands for a sugar-binding protein isolated from a random peptide library.

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