Stereocontrol of 1,2‐‐Glycosylation by Remote
            <i>O</i>
            ‐Acyl Protecting Groups

Komarova, Bozhena S.; Ustyuzhanina, Nadezhda E.; Tsvetkov, Yury E.; Nifantiev, Nikolay E.

doi:10.1002/9783527658947.ch5

Cited by 20 publications

(20 citation statements)

References 83 publications

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“…Whereas the glycosylating properties of fucosazide donors have received relatively little attention, there is a large body of data available on the stereoselective introduction of fucosyl linkages. 23 − 34 …”

Section: Results and Discussionmentioning

confidence: 99%

“…The observed β-selectivity in the condensation reactions of the benzoylated fucosazide donors with ethanol and cyclohexanol strongly argue against a remote participation scenario for these donors. 23 The selectivity in these reactions is better explained with the α-anomeric triflates or oxosulfonium triflates 16 as glycosylating species ( Scheme 2 ). The presence of benzoyl groups on the fucosazide donors stabilizes these intermediates, as judged from the higher decomposition temperature found in the variable temperature NMR measurements.…”

Section: Results and Discussionmentioning

confidence: 99%

“…To map the reactivity and selectivity of fucosazide donors, we investigated a set of donors having different protecting groups. Whereas the glycosylating properties of fucosazide donors have received relatively little attention, there is a large body of data available on the stereoselective introduction of fucosyl linkages. − …”

Section: Results and Discussionmentioning

confidence: 99%

“…It appears that the α-fucosyl linkage can be installed with relative ease. For the stereoselective construction of this linkage, fucosyl building blocks, bearing acyl protecting groups at C3 and/or C4, are commonly used, and it is often assumed that these groups are capable of “remote participation” . Of note, tri- O -benzyl-protected fucosyl donors have also been employed, and these have also been reported to provide the desired 1,2- cis fucosyl linkages with good selectivity. , No mechanistic rationale has been forwarded to account for this striking selectivity.…”

Section: Results and Discussionmentioning

confidence: 99%

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Mapping the Reactivity and Selectivity of 2-Azidofucosyl Donors for the Assembly ofN-Acetylfucosamine-Containing Bacterial Oligosaccharides

et al. 2017

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The synthesis of complex oligosaccharides is often hindered by a lack of knowledge on the reactivity and selectivity of their constituent building blocks. We investigated the reactivity and selectivity of 2-azidofucosyl (FucN3) donors, valuable synthons in the synthesis of 2-acetamido-2-deoxyfucose (FucNAc) containing oligosaccharides. Six FucN3 donors, bearing benzyl, benzoyl, or tert-butyldimethylsilyl protecting groups at the C3-O and C4-O positions, were synthesized, and their reactivity was assessed in a series of glycosylations using acceptors of varying nucleophilicity and size. It was found that more reactive nucleophiles and electron-withdrawing benzoyl groups on the donor favor the formation of β-glycosides, while poorly reactive nucleophiles and electron-donating protecting groups on the donor favor α-glycosidic bond formation. Low-temperature NMR activation studies of Bn- and Bz-protected donors revealed the formation of covalent FucN3 triflates and oxosulfonium triflates. From these results, a mechanistic explanation is offered in which more reactive acceptors preferentially react via an SN2-like pathway, while less reactive acceptors react via an SN1-like pathway. The knowledge obtained in this reactivity study was then applied in the construction of α-FucN3 linkages relevant to bacterial saccharides. Finally, a modular synthesis of the Staphylococcus aureus type 5 capsular polysaccharide repeating unit, a trisaccharide consisting of two FucNAc units, is described.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

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Mapping the Reactivity and Selectivity of 2-Azidofucosyl Donors for the Assembly ofN-Acetylfucosamine-Containing Bacterial Oligosaccharides

et al. 2017

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“…To achieve a glycosylation with acceptable α -selectivity, 2-azido-2-deoxy-D-glucosyl donor 8 was employed in view of possible remote participation of the Lev ester at C-6. 16 First, the glycosylation of inositol derivative 7 (see the SI) with glucosaminyl imidate 8 (see the SI) was carried out in the presence of catalytic TBSOTf in DCM at −30 °C, and while the pseudo-disaccharide 12 could be isolated in acceptable yield (74%), the anomeric outcome was unfavorable ( α / β = 1.0/1.3). The use of diethyl ether as the reaction solvent did not substantially improve the stereoselective outcome of the glycosylation ( α / β = 1/1); however, by employing toluene/1,4-dioxane (1:3 v/v), 17 the pseudo-disaccharide 12 was isolated in 84% yield mainly as the α -anomer ( α / β = 4/1).…”

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confidence: 99%

Synthesis of a Glycosylphosphatidylinositol Anchor Derived from Leishmania donovani That Can Be Functionalized by Cu-Catalyzed Azide–Alkyne Cycloadditions

Ding

Li²,

Chinoy³

et al. 2017

Org. Lett.

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A flexible assembly strategy has been developed for the synthesis of Leishmania donovani GPI anchors that bear a clickable alkyne tag. This strategy is based on the use of the 2-naphthylmethyl (Nap) ethers and levulinoyl (Lev) ester for permanent protection of hydroxyls. Removal of seven Nap ethers by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone made it possible to prepare GPIs having an alkyne functionality that could be modified by Cu(I)-catalyzed [3 + 2] cycloadditions to install tags for imaging studies.

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Protecting Group Strategies in Carbohydrate Chemistry

2018

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License: Article 25fa pilot End User Agreement This publication is distributed under the terms of Article 25fa of the Dutch Copyright Act (Auteurswet) with explicit consent by the author. Dutch law entitles the maker of a short scientific work funded either wholly or partially by Dutch public funds to make that work publicly available for no consideration following a reasonable period of time after the work was first published, provided that clear reference is made to the source of the first publication of the work. This publication is distributed under The Association of Universities in the Netherlands (VSNU) 'Article 25fa implementation' pilot project. In this pilot research outputs of researchers employed by Dutch Universities that comply with the legal requirements of Article 25fa of the Dutch Copyright Act are distributed online and free of cost or other barriers in institutional repositories. Research outputs are distributed six months after their first online publication in the original published version and with proper attribution to the source of the original publication. You are permitted to download and use the publication for personal purposes. All rights remain with the author(s) and/or copyrights owner(s) of this work. Any use of the publication other than authorised under this licence or copyright law is prohibited. If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons.

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Stereocontrol of 1,2‐‐Glycosylation by Remote O ‐Acyl Protecting Groups

Cited by 20 publications

References 83 publications

Mapping the Reactivity and Selectivity of 2-Azidofucosyl Donors for the Assembly ofN-Acetylfucosamine-Containing Bacterial Oligosaccharides

Mapping the Reactivity and Selectivity of 2-Azidofucosyl Donors for the Assembly ofN-Acetylfucosamine-Containing Bacterial Oligosaccharides

Synthesis of a Glycosylphosphatidylinositol Anchor Derived from Leishmania donovani That Can Be Functionalized by Cu-Catalyzed Azide–Alkyne Cycloadditions

Protecting Group Strategies in Carbohydrate Chemistry

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