Auf dem Weg zur automatisierten Oligosaccharid‐ Synthese

Hsu, Che‐Chang; Hung, Shang‐Cheng; Wu, Chung‐Yi; Wong, Chi‐Huey

doi:10.1002/ange.201100125

Cited by 51 publications

(15 citation statements)

References 584 publications

(412 reference statements)

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“…Advanced technology for oligosaccharide synthesis involves one-pot glycosylation strategies and automated solid phase synthesis. [3][4][5][6] One-pot glycosylation refers to sequential coupling of glycosyl building blocks to produce an oligosaccharide in the same reaction pot, obviating the need for reptitive intermediate isolation and transformation of the anomeric group.…”

Section: Introductionmentioning

confidence: 99%

Iterative One‐Pot α‐Glycosylation Strategy: Application to Oligosaccharide Synthesis

Liu¹,

Mulani²,

Mong³

2012

Adv Synth Catal

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Based on the combined use of dimethyl-A C H T U N G T R E N N U N G formamide (DMF) modulation and neighboring group participation, three iterative one-pot a-glycosylation methods, i.e., one-pot (a,a)-, one-pot (b,a)-, and one-pot (a,b)-glycosylations, were developed. These methods are applicable to a range of thioglycosyl donors, confer stereocontrol in a-/b-glycosidic bond formation, and thus provide for rapid access to oligosaccharides with various permutations of anomeric configurations. The utility of these one-pot glycosylation methods is demonstrated in the synthesis of eight non-natural and natural oligosaccharide targets, including the core 1 serine conjugate, core 8

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Section: Introductionmentioning

confidence: 99%

Iterative One‐Pot α‐Glycosylation Strategy: Application to Oligosaccharide Synthesis

Liu¹,

Mulani²,

Mong³

2012

Adv Synth Catal

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“…Contemporary advances in synthesis emphasize the efficiency of preparing complex oligosaccharides by using automated synthesis, [4] one-pot procedures, [5] and chemoenzymatic processes. [6] One of the most exciting developments is exemplified in the multi-gram production of iGb3, which was obtained as the free trisaccharide by using E. coli .…”

Section: Introductionmentioning

confidence: 99%

Two‐Step Functionalization of Oligosaccharides Using Glycosyl Iodide and Trimethylene Oxide and Its Applications to Multivalent Glycoconjugates

Hsieh

Davis

Hoch

et al. 2014

Chemistry A European J

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Oligosaccharide conjugates, such as glycoproteins and glycolipids, are potential chemotherapeutics and also serve as useful tools for understanding the biological roles of carbohydrates. With many modern isolation and synthetic technologies providing access to a wide variety of free sugars, there is increasing need for general methodologies for carbohydrate functionalization. Herein, we report a two-step methodology for the conjugation of per-O-acetylated oligosaccharides to functionalized linkers that can be used for various displays. Oligosaccharides obtained from both synthetic and commercial sources were converted to glycosyl iodides and activated with I2 to form reactive donors that were subsequently trapped with trimethylene oxide to form iodopropyl conjugates in a single step. The terminal iodide served as a chemical handle for further modification. Conversion into the corresponding azide followed by copper-catalyzed azide–alkyne cycloaddition afforded multivalent glycoconjugates of Gb3 for further investigation as anti-cancer therapeutics.

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“…Some of the popular halonium-based promoters are challenging to use in the presence of alkenes, [20] because they tend to give various addition by-products, thereby ultimately resulting in the cleavage of the alkenyl moiety. These issues with solubility, undesired by-products, stability, or reagent handling are particularly problematic in the context of the development of robust automated protocols [21,22] for oligosaccharide synthesis. To circumvent some of these issues with current promoter systems, we herein report a straightforward method for the activation of thiopropylglycosides for coupling to various acceptors in good to excellent yields by utilizing a bismuth(V) compound without additional additives/copromoters.…”

mentioning

confidence: 99%

“…A recent report [33] demonstrates the use of Bi V salts and ylides in carbon-carbon and carbon-heteroatom bond-forming reactions. We were curious as to the thiophilicity of Bi V complexes as well as the possibility of the addition of solubilizing ligands on Bi III , but soon we discovered the challenges of trying to synthesize and characterize new bismuth-containing compounds.Given the current limitations in the definitive characterization [22] of new bismuth compounds in solution, we next sought a complex that was amenable to crystallization. We chose a pentavalent bismuth compound containing three phenyl and two triflate groups, namely triphenyl bismuth ditriflate (2).…”

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confidence: 99%

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Bismuth(V)‐Mediated Thioglycoside Activation

2013

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Chemical glycosylation [1,2] is a crucial step in any oligosaccharide [3] synthesis. [4,5] Among the different classes of commonly used glycosyl donors, [2] thioglycosides [6, 7] offer distinct advantages. Thioglycoside donors are relatively simple to prepare, are stable under various reactions for protectinggroup manipulations, and offer orthogonality in their activation in the presence of other glycosyl donors. [8] As a result, a wide variety of promoters have been developed for activation of these donors in the past 20 years: [2] from heavy metal-cation-based promoters (Hg II sulfate), [9] to the current halonium-based reagents [e.g., N-iodosuccinimide/trifluoromethane sulfonic acid (NIS/TfOH), [10] N-bromosuccinimide (NBS), [11] ICl or IBr/AgOTf, [12] etc.], alkylating reagents [methyl triflate (MeOTf)], [13] and organosulfur-based promoters [e.g., dimethyl(thiomethyl)sulfonium triflate (DMTST), [14] methylsulfenyl triflate (MeSOTf), [15] dimethyl disulfide/triflic anhydride (Me 2 S/Tf 2 O), [16] benzenesulfinylpiperidine/triflic anhydride (BSP/TTBP), [17] N-(phenylthio)-ecaprolactam-Tf 2 O, [18] etc.]. A recent method applies singleelectron transfer using ruthenium or iridium-containing catalysts that are active under visible light [19] to activate thioglycosides. Although these methods have been effective in carrying out a range of glycosylations, most of these still have a limited scope. Generally, these activations need excess amounts of promoters, [2,[9][10][11][12][13][14][15][16][17][18] or require a co-promoter to form the reactive intermediates. Moreover, present methods often require extremely low temperatures (< À20 8C) as a result of generating reactive intermediates. Some of the popular halonium-based promoters are challenging to use in the presence of alkenes, [20] because they tend to give various addition by-products, thereby ultimately resulting in the cleavage of the alkenyl moiety. These issues with solubility, undesired by-products, stability, or reagent handling are particularly problematic in the context of the development of robust automated protocols [21,22] for oligosaccharide synthesis. To circumvent some of these issues with current promoter systems, we herein report a straightforward method for the activation of thiopropylglycosides for coupling to various acceptors in good to excellent yields by utilizing a bismuth(V) compound without additional additives/copromoters.In lieu of the available promoters based on heavy-metal cations, bismuth presents interesting possibilities. Bismuth is a post-transition metal and like its neighboring metals such as mercury and lead, it is considered thiophilic as well as soft Lewis acidic. However, unlike Hg and Pb compounds, bismuth [23] is not only inexpensive, but also nontoxic. Unfortunately, despite its popularity as a treatment for digestive problems, [24] the synthetic utility of bismuth compounds remains relatively unexplored. However, the chemistry of this element [25] has gained considerable interest [26,27] over the past decade. [28] V...

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Auf dem Weg zur automatisierten Oligosaccharid‐ Synthese

Cited by 51 publications

References 584 publications

Iterative One‐Pot α‐Glycosylation Strategy: Application to Oligosaccharide Synthesis

Iterative One‐Pot α‐Glycosylation Strategy: Application to Oligosaccharide Synthesis

Two‐Step Functionalization of Oligosaccharides Using Glycosyl Iodide and Trimethylene Oxide and Its Applications to Multivalent Glycoconjugates

Bismuth(V)‐Mediated Thioglycoside Activation

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