A Direct Method for β-Selective Glycosylation with an N-Acetylglucosamine Donor Armed by a 4-O-TBDMS Protecting Group

Tanaka, Hidefumi; Hamaya, Yu; Kotsuki, Hiyoshizo

doi:10.3390/molecules22030429

Cited by 4 publications

(5 citation statements)

References 20 publications

(19 reference statements)

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“…The optimal result was achieved with 4-O-TBDMS imidate 6, which was efficiently prepared from 2 by silylation of 4-OH (→4), hydrolysis of the anomeric SEt-group (Lay et al, 1998) →5, and trichloroacetimidate formation, for a total yield of 81% in three steps (Scheme 1). As 4-O-silylated donor 6 must possess higher reactivity than 4-O-acylated counterparts (Tanaka et al, 2017), one could anticipate a decrease of the proportion of aglycon transfer in its reaction with 2 Gildersleeve, 2006, 2007). Indeed, TMSOTf-promoted glycosylation of acceptor 2 with imidate 6 at low temperature provided the requisite disaccharide donor 7 in high yield and was practically unaccompanied by aglycon transfer.…”

Section: Chemistrymentioning

confidence: 99%

Synthesis of Biotin-Tagged Chitosan Oligosaccharides and Assessment of Their Immunomodulatory Activity

Tsvetkov

Paulovičová

et al. 2020

Front. Chem.

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Chitin, a polymer of β-(1→4)-linked N-acetyl-d-glucosamine, is one of the main polysaccharide components of the fungal cell wall. Its N-deacetylated form, chitosan, is enzymatically produced in the cell wall by chitin deacetylases. It exerts immunomodulative, anti-inflammatory, anti-cancer, anti-bacterial, and anti-fungal activities with various medical applications. To study the immunobiological properties of chitosan oligosaccharides, we synthesized a series of β-(1→4)-linked N-acetyl-d-glucosamine oligomers comprising 3, 5, and 7 monosaccharide units equipped with biotin tags. The key synthetic intermediate employed for oligosaccharide chain elongation, a disaccharide thioglycoside, was prepared by orthogonal glycosylation of a 4-OH thioglycoside acceptor with a glycosyl trichloroacetimidate bearing the temporary 4-O-tert-butyldimethylsilyl group. The use of silyl protection suppressed aglycon transfer and provided a high yield for the target disaccharide donor. Using synthesized chitosan oligomers, as well as previously obtained chitin counterparts, the immunobiological relationship between these synthetic oligosaccharides and RAW 264.7 cells was studied in vitro. Evaluation of cell proliferation, phagocytosis, respiratory burst, and Th1, Th2, Th17, and Treg polarized cytokine expression demonstrated effective immune responsiveness and immunomodulation in RAW 264.7 cells exposed to chitin- and chitosan-derived oligosaccharides. Macrophage reactivity was accompanied by significant inductive dose- and structure-dependent protective Th1 and Th17 polarization, which was greater with exposure to chitosan- rather than chitin-derived oligosaccharides. Moreover, no antiproliferative or cytotoxic effects were observed, even following prolonged 48 h exposure. The obtained results demonstrate the potent immunobiological activity of these synthetically prepared chito-oligosaccharides.

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Section: Chemistrymentioning

confidence: 99%

Synthesis of Biotin-Tagged Chitosan Oligosaccharides and Assessment of Their Immunomodulatory Activity

Tsvetkov

Paulovičová

et al. 2020

Front. Chem.

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“…However sterically hindered acceptors were found to be less efficient under these reaction conditions (Scheme 20). 41 The stereoselectivity of couplings of benzyl ether protected gluco-, galacto-, and mannopyranosylthioglycosides has been studied using promoters like benzenesulfinyl piperidine/ trifluoromethanesulfonic anhydride (BSP), diphenyl sulfoxide/ trifluoromethanesulfonic anhydride (Ph 2 SO), and N-iodosuccinimide/trimethylsilyl trifluoromethanesulfonate (NIS/TMSOTf). In the glucose series, the NIS/TMSOTf combination provided significantly different stereoselectivities than other methods.…”

Section: Silane Assisted Glycosylation For the Synthesis Of Apis And ...mentioning

confidence: 99%

“…However sterically hindered acceptors were found to be less efficient under these reaction conditions (Scheme 20). 41…”

Section: Silane Assisted Glycosylation For the Synthesis Of Apis And ...mentioning

confidence: 99%

Silane promoted glycosylation and its applications for synthesis of sugar compounds and active pharmaceutical ingredients (APIs)

Kar¹,

Nanda²,

Ravichandiran

et al. 2022

New J. Chem.

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“…26 The rateenhancing effect of a single TBS has also been observed in glycosylation with GlcNAc donors. 27 Widmalm and collaborators have investigated disaccharide donors that are conformationally armed using TBS ethers. With a kojibiose-like disaccharide thioglycoside donor 15, the acceptor 16 was glycosylated in excellent yield and stereoselectivity using NIS and TfOH promotion (Scheme 5).…”

Section: Account Synlettmentioning

confidence: 99%

Silylated Sugars – Synthesis and Properties

Bols

Frihed

Pedersen

et al. 2021

Synlett

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Silicon has been used in carbohydrate chemistry for half a century, but mostly as a protective group for sugar alcohols. Recently, the use of silicon has expanded to functionalization via C–H activation, conformational arming of glycosyl donors, and conformational alteration of carbohydrates. Silicon has proven useful as more than a protective group and during the last one and a half decades we have demonstrated how it influences both the reactivity of glycosyl donors and stereochemical outcome of glycosylations. Silicon can also be attached directly to the sugar C-backbone, which has even more pronounced effects on the chemistry and properties of the molecules. In this Account, we will give a tour through our work involving silicon and carbohydrates.1 Introduction2 Conformational Arming of Glycosyl Donors with Silyl Groups3 Silyl Protective Groups for Tethering Glycosyl Donors4. Si–C Glycosides via C–H Activation4.1 C–H Activation and Oxidation of Methyl 6-Deoxy-l-glycosides4.2 Synthesis of All Eight 6-Deoxy-l-sugars4.3 Synthesis of All Eight l-Sugars by C–H Activation4.4 Modification of the Oxasilolane Ring5 C–Si in Glycosyl Donors – Activating or Not?6 Si–C-Substituted Pyranosides7 Perspective

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A Direct Method for β-Selective Glycosylation with an N-Acetylglucosamine Donor Armed by a 4-O-TBDMS Protecting Group

Cited by 4 publications

References 20 publications

Synthesis of Biotin-Tagged Chitosan Oligosaccharides and Assessment of Their Immunomodulatory Activity

Synthesis of Biotin-Tagged Chitosan Oligosaccharides and Assessment of Their Immunomodulatory Activity

Silane promoted glycosylation and its applications for synthesis of sugar compounds and active pharmaceutical ingredients (APIs)

Silylated Sugars – Synthesis and Properties

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