Direct chemical glycosylation with pentenyl- and thioglycoside donors of N-acetylglucosamine

Krag, Jonas; Christiansen, Mira Steinicke; Petersen, Jette G.; Jensen, Henrik H.

doi:10.1016/j.carres.2010.02.013

Cited by 24 publications

(31 citation statements)

References 34 publications

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“…Proper optimization of the reaction conditions of this metal‐free glycosylation afforded the coupled product in significant yields. Direct glycosylation with GlcNAc has also been reported by Jensen and co‐workers through the activation of thioglycosides 166 or pentenyl glycosides 167 by using various metal triflates (Table ). However, when glycosylated with carbohydrate acceptors, the yields obtained were poorer than simple acceptors like 1‐octanol or (−)‐menthol.…”

Section: Glycosylationsmentioning

confidence: 72%

Chemical O‐Glycosylations: An Overview

2016

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The development of glycobiology relies on the sources of particular oligosaccharides in their purest forms. As the isolation of the oligosaccharide structures from natural sources is not a reliable option for providing samples with homogeneity, chemical means become pertinent. The growing demand for diverse oligosaccharide structures has prompted the advancement of chemical strategies to stitch sugar molecules with precise stereo‐ and regioselectivity through the formation of glycosidic bonds. This Review will focus on the key developments towards chemical O‐glycosylations in the current century. Synthesis of novel glycosyl donors and acceptors and their unique activation for successful glycosylation are discussed. This Review concludes with a summary of recent developments and comments on future prospects.

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Section: Glycosylationsmentioning

confidence: 72%

Chemical O‐Glycosylations: An Overview

2016

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“…The stereochemistry of the donor was assigned based on the 1 J C-1,1-H coupling constant (161 Hz). [56] Traditionally, TfOH is used for NIS activation of thioglycosides, but other metal-based Lewis acidic triflates [AgOTf, [57] La(OTf ) 3 [58] or Sc(OTf ) 3 , Yb(OTf) 3 , Cu(OTf) 2 , Mg(OTf ) 2 , and Zn(OTf ) 2 ] [59] are also known to be capable of this reaction. This resulted in the conversion of both the donor and the acceptor, but the reaction mixture appeared to be complex.…”

Section: Resultsmentioning

confidence: 99%

Glycosyl ortho‐Methoxybenzoates: Catalytically Activated Glycosyl Donors with an Easily Removable and Recyclable Leaving Group

et al. 2016

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We describe the β‐ortho‐methoxybenzoate as a shelf stable and practical C‐1 nucleofuge for catalytic chemical glycosylation in which the benzoic acid by‐product can be easily removed, reisolated, and potentially recycled after the glycosylation reaction. This new type of glycosyl donor can be efficiently activated by a range of promoters, including Bi(OTf)3, Fe(OTf)3, TMSOTf (TMS = trimethylsilyl), and triflic acid, with low (<10 mol‐%) catalyst loadings. The donor shows higher reactivity than analogous benzoate, p‐methoxybenzoate and p‐cyano‐o‐methoxybenzoate donors. In glycosylation reactions with o‐methoxybenzoate donors, the yields of disaccharide products were good to excellent for various glycosyl acceptors, including a carbohydrate‐based secondary alcohol. Furthermore, β‐selective mannosylation was achieved with a Crich‐type donor at 0 °C to ambient temperature, without donor preactivation. The donor was also used for the first step of a one‐pot two‐step glycosylation to obtain a trisaccharide; the second coupling involved activation of a thioglycoside with NIS/TMSOTf (NIS = N‐iodosuccinimide). We believe that this offers a good alternative to current protocols.

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“…Glycosylation of acetate 10 with pentene-1-ol mediated by TMSOTf gave the known compound 11 . 32 Zemplén deacetylation followed by addition of the 4,6- O -benzylidine protection using benzyaldehyde dimethyl acetal and p -toluenesulfonic acid resulted in previously reported intermediate 13 . 33 Next, the free alcohol was masked by treatment with levulinic acid in the presence of an activating system composed of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDCI) and DMAP to yield 14 .…”

Section: Resultsmentioning

confidence: 92%

Total synthesis of trifluorobutyryl-modified, protected sialyl Lewis X by a convergent [2+2] approach

Akçay

Ramphal

d’Alarcao

et al. 2015

Tetrahedron Letters

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Structural and quantitative changes in the expression of sialic acid residues on the surface of eukaryotic cells profoundly influence a broad range of biological processes including inflammation, antigen recognition, microbial attachment, and tumor metastasis. Uptake and incorporation of sialic acid analogues in mammalian cells enable structure-function studies and perturbation of specific recognition events. Our group has recently shown that a trifluorobutyryl-modified sialic acid metabolite diminishes the adhesion of mammalian cells to E and P-selectin, presumably by leading to the expression of fluorinated sLex epitopes on cell surfaces, and interfering with the sLex-selectin interactions that are well known in mediating tumor cell migration.1 For studies directed towards understanding the molecular basis of this reduced adhesion, chemical synthesis of trifluorobutyrylated sialyl Lewis x (C4F3--sLex) was crucial. We have developed a highly efficient [2+2] approach for the assembly of C4F3-sLex on a preparative scale that contains versatile protective groups allowing the glycan to be surface immobilized or solubilized as needed for biophysical studies to investigate selectin interactions. This strategy can, in principle, be used for preparation of other N-modified sLex analogues.

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Direct chemical glycosylation with pentenyl- and thioglycoside donors of N-acetylglucosamine

Cited by 24 publications

References 34 publications

Chemical O‐Glycosylations: An Overview

Chemical O‐Glycosylations: An Overview

Glycosyl ortho‐Methoxybenzoates: Catalytically Activated Glycosyl Donors with an Easily Removable and Recyclable Leaving Group

Total synthesis of trifluorobutyryl-modified, protected sialyl Lewis X by a convergent [2+2] approach

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