Differences in reactivity of N-acetyl- and N,N-diacetylsialyl chlorides caused by their different supramolecular organization in solutions

Orlova, A. V.; Laptinskaya, T. V.; Bovin, Nicolai V.; Kononov, L. O.

doi:10.1007/s11172-017-1999-x

Cited by 19 publications

(7 citation statements)

References 50 publications

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“…It has recently been demonstrated [31] that N , N ‐diacetylsialyl chloride 1 b [32] with two acetyl groups at N(5) is considerably more reactive that the parent N ‐acetylsialyl chloride 1 a in glycosylation reactions including PTC glycosylations [31a] performed under similar conditions (Bu 4 NHSO 4 , AcOEt, 1 M aq Na 2 CO 3 ). This increased reactivity was attributed [31a] to formation of more loose supramers of sialyl donor in solutions of 1 b (as evidenced by dynamic light scattering by solutions of 1 a and 1 b in AcOEt saturated with water) [31a] with increased accessibility of individual molecules for the attack by a nucleophile [33]…”

Section: Resultsmentioning

confidence: 99%

Black Swan in Phase Transfer Catalysis: Influence of Mixing Mode on the Stereoselectivity of Glycosylation

et al. 2022

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Phase transfer catalysis (PTC) is widely used for the preparation of anomerically pure aryl glycosides by glycosylation of phenols with glycosyl halides. Here, we attempted to synthesize 4‐(3‐chloropropoxy)phenyl (CPP) sialoside – a useful Janus glycoside for neoglycoconjugate synthesis. A batch glycosylation reaction under typical PTC conditions (N‐acetylsialyl chloride, 4‐(3‐chloropropoxy)phenol, Bu4NHSO4, AcOEt, 10 % aq Na2CO3) resulted in formation of CPP sialoside as a single anomer, albeit in low yield. Conversely, the PTC glycosylation in flow using Comet X‐01 micromixer doubled the yield of CPP sialoside, which was obtained as a mixture of anomers suggesting the change in the reaction mechanism apparently induced by the change in mixing mode. An increase in flow rate led to further loss of stereoselectivity while the use of T‐shaped mixer increased stereoselectivity. Similar results were obtained for N,N‐diacetylsialyl chloride and two other para‐alkoxy‐substituted phenols suggesting generality of the discovered phenomenon.

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Section: Resultsmentioning

confidence: 99%

Black Swan in Phase Transfer Catalysis: Influence of Mixing Mode on the Stereoselectivity of Glycosylation

et al. 2022

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“…Apparently, one must consider differences in the structures of reaction solutions in each case, which could include differences in structures of supramers (and references cited therein) formed by both acid reagent , and carbohydrate substrate. This issue deserves a special physico-chemical study, similar to those we conducted − for other systems.…”

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confidence: 99%

A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions

et al. 2018

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A pyranose ring contraction of ethyl 1-thio-β-d-galactopyranosides has been discovered that proceeds with retention of aglycon under mildly acidic conditions (aq TFA in CH2Cl2). Key factors for success of this rearrangement are the presence of bulky silyl (TIPS or TBDPS) substituents at both O-2 and O-3 and a free hydroxy group at C-4 (derivatives with acid-labile protective groups at O-4 will also engage in this reaction). The rearrangement cleanly proceeds for 2,3-di-O-TIPS derivatives with two hydroxy groups at C-4 and C-6, acid-labile TES groups at O-4 and O-6, or one acyl substituent (Bz, ClAc) at O-6. A possibility to switch the direction of the debenzylidenation reaction in 4,6-O-benzylidene-2,3-di-O-TIPS/TBDPS derivatives by the choice of an acid (TFA, which cleanly gives furanose, versus AcOH, which cleaves benzylidene acetal only) may present an advantage in the divergent synthesis of selectively protected glycosyl donors (either in furanose or pyranose form) useful for the synthesis of biologically important oligosaccharides.

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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

Preprint

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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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Differences in reactivity of N-acetyl- and N,N-diacetylsialyl chlorides caused by their different supramolecular organization in solutions

Cited by 19 publications

References 50 publications

Black Swan in Phase Transfer Catalysis: Influence of Mixing Mode on the Stereoselectivity of Glycosylation

Black Swan in Phase Transfer Catalysis: Influence of Mixing Mode on the Stereoselectivity of Glycosylation

A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions

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

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