Stereoselective sialylation with O-trifluoroacetylated thiosialosides: hydrogen bonding involved?

Podvalnyy, Nikita M.; Malysheva, N. N.; Panova, Maria V.; Zinin, Alexander I.; Chizhov, Alexander O.; Orlova, A. V.; Kononov, L. O.

doi:10.1016/j.carres.2017.09.002

Cited by 21 publications

(43 citation statements)

References 93 publications

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“…In the course of their investigation into their supramer concept, numerous such studies were reported by Kononov and coworkers for various sialidation reactions. 286–290 A curious inverse dependence on acceptor concentration in certain sialidation reactions was reported by Xing and coworkers and attributed to a change on supramer constitution. 332 Yet further examples have been provided by Kononov who showed, inter alia, the influence of donor concentration on the stereochemical outcome of the reaction of an arabinofuranosyl bromide with dibutyl phosphate (Scheme 65).…”

Section: Use Of Cation Clocks To Determine Molecularitymentioning

confidence: 91%

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

et al. 2018

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A critical review of the state-of-the-art evidence in support of the mechanisms of glycosylation reactions is provided. Factors affecting the stability of putative oxocarbenium ions as intermediates at the S1 end of the mechanistic continuum are first surveyed before the evidence, spectroscopic and indirect, for the existence of such species on the time scale of glycosylation reactions is presented. Current models for diastereoselectivity in nucleophilic attack on oxocarbenium ions are then described. Evidence in support of the intermediacy of activated covalent glycosyl donors is reviewed, before the influences of the structure of the nucleophile, of the solvent, of temperature, and of donor-acceptor hydrogen bonding on the mechanism of glycosylation reactions are surveyed. Studies on the kinetics of glycosylation reactions and the use of kinetic isotope effects for the determination of transition-state structure are presented, before computational models are finally surveyed. The review concludes with a critical appraisal of the state of the art.

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Section: Use Of Cation Clocks To Determine Molecularitymentioning

confidence: 91%

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

et al. 2018

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“…The observed differences in specificity of antibodies generated against the two sets We have recently argued [103][104][105] that the sometimes observed profound influence of the nature of (functionalized) aglycon in a glycosyl acceptor may be related to formation of reaction solutions with modified structure that are featured by the presence of different supramolecular assemblies of reagents (supramers [102]) in solution. In a similar fashion, solutions of Ara6C2NH2-GNPs 3 with shorter and more hydrophobic С2 spacer aglycon might form more dense [106,107] supramers in aqueous solutions [102,[108][109][110] which eventually would form more clustered Ara6glycan domains on the surface of Ara6-GNPs.…”

Section: Discussionmentioning

confidence: 93%

Preparation of glyco-gold nanoparticles carrying synthetic mycobacterial hexaarabinofuranoside and their evaluation in vivo

Burygin¹,

Abronina²,

Podvalnyy³

et al. 2019

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Some bacterial glycans are specific markers for detection and serological identification of microorganisms and are widely used as antigenic components of vaccines. The use of gold nanoparticles as carriers for glyco-epitopes is becoming an important alternative to the traditional conjugation with proteins and synthetic polymers. In this study, we aimed at preparation and evaluation in vivo of glyco-gold nanoparticles (glyco-GNPs) bearing the terminal branched hexaarabinofuranoside fragment (Ara6) of arabinan domains of lipoarabinomannan and arabinogalactan, which are principal polysaccharides of the cell wall of Mycobacterium tuberculosis, the causative agent of tuberculosis. Specifically, we were interested in checking if the antibodies generated against Ara6-GNPs would recognize the natural saccharides on the cell surface of different mycobacterial strains. Two synthetic Ara6 glycosides with amino-functionalized spacer aglycons differing in length and hydrophilicity were directly conjugated with spherical gold nanoparticles (d = 15 nm) to give two sets of glyco-GNPs which were used for immunization of rabbits. Dot assay revealed cross-reactions for the two obtained antisera with the hexaarabinofuranoside with 2-aminoethyl aglycon used for the preparation of glyco-GNPs. Both antisera contained high titers of antibodies specific for Mycobacteria as shown by enzyme-linked immunosorbent assay using M. bovis and M. smegmatis cells as antigens while gave a weak response with M. phlei cells and no interaction with E. coli cells. The results obtained suggest that glyco-GNPs are promising agents for generation of anti-mycobacterial antibodies.

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“…We speculate that a similar hydrogen‐bond mediated complexation of glycosyl acceptor with oxacarbenium ion B (Scheme ) derived from glycosyl donor might be involved in glycosylation of glycosyl acceptor 20 by a mixture of N ‐TFA‐protected glucosamine N ‐phenyltrifluoroacetimidate 6α and 2‐trifluoromethyl‐oxazoline 7 . We have to stress that due to a strong electron‐withdrawing effect of trifluoromethyl group, which makes trifluoroacetamide proton present in N ‐TFA‐derivatives (including oxacarbenium ion B ) the sole strong hydrogen‐bond donor in the reaction mixture, yet another hydrogen‐bonding mode becomes feasible if not dominating. We propose that in case of NHTFA derivatives, unlike NHAc‐derivatives (vide supra), hydrogen‐bonding complexation between glycosyl donor and glycosyl acceptor would involve hydrogen atom of NHTFA at C‐2 and oxygen atom of the hydroxy group of glycosyl acceptor (intermediate B2 , Scheme , b ) and thus lead to the formation of 1,2‐ cis ‐glycoside.…”

Section: Resultsmentioning

confidence: 99%

“…We propose that in case of NHTFA derivatives, unlike NHAc‐derivatives (vide supra), hydrogen‐bonding complexation between glycosyl donor and glycosyl acceptor would involve hydrogen atom of NHTFA at C‐2 and oxygen atom of the hydroxy group of glycosyl acceptor (intermediate B2 , Scheme , b ) and thus lead to the formation of 1,2‐ cis ‐glycoside. Note that carbonyl oxygen of NHTFA group is a rather poor hydrogen‐bond acceptor in comparison with carbonyl oxygens of Ac and Bz groups . For this reason, the possibility of its participation in hydrogen‐bonding can be disregarded (at least in the first approximation).…”

Section: Resultsmentioning

confidence: 99%

Unusual Outcome of Glycosylation: Hydrogen‐Bond Mediated Control of Stereoselectivity by N‐Trifluoroacetyl Group?

et al. 2020

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During the synthesis of protected tetrasaccharide fragment of the repeating unit of polysaccharide of Azospirillum brasilense sp7 we found that glycosylation with a mixture of protected N‐trifluoroacetyl (TFA)‐protected glucosamine N‐phenyltrifluoroacetimidate and the corresponding 2‐trifluoromethyl‐oxazoline led to 1,2‐cis‐linked glycoside along with the expected 1,2‐trans‐linked isomer. This fact looks quite unusual bearing in mind that both N‐TFA‐containing glycosyl donor and 2‐trifluoromethyl‐oxazoline are usually expected to favor the formation of 1,2‐trans‐glycosides. Formation of 1,2‐cis‐glycoside was explained by hydrogen‐bond mediated complexation of hydrogen atom of NHTFA at C‐2 of oxacarbenium ion derived from glycosyl donor and oxygen atom of hydroxy group of the incoming nucleophile. Conversely, glycosylations with N‐phthaloyl protected glycosyl donors resulted in exclusive formation of 1,2‐trans‐isomer presumably due to a significant steric effect and the absence of additional hydrogen‐bonding sites of N‐phthaloyl group.

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Stereoselective sialylation with O-trifluoroacetylated thiosialosides: hydrogen bonding involved?

Cited by 21 publications

References 93 publications

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

Preparation of glyco-gold nanoparticles carrying synthetic mycobacterial hexaarabinofuranoside and their evaluation in vivo

Unusual Outcome of Glycosylation: Hydrogen‐Bond Mediated Control of Stereoselectivity by N‐Trifluoroacetyl Group?

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Stereoselective sialylation with O-trifluoroacetylated thiosialosides: hydrogen bonding involved?

Cited by 21 publications

References 93 publications

The Experimental Evidence in Support of Glycosylation Mechanisms at the SN1–SN2 Interface

The Experimental Evidence in Support of Glycosylation Mechanisms at the SN1–SN2 Interface

Preparation of glyco-gold nanoparticles carrying synthetic mycobacterial hexaarabinofuranoside and their evaluation in vivo

Unusual Outcome of Glycosylation: Hydrogen‐Bond Mediated Control of Stereoselectivity by N‐Trifluoroacetyl Group?

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The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface