Synthesis of Lactose-Based <i>S</i>-Linked Sialylmimetics of α(2,3)-Sialosides

Liakatos, Angela; Kiefel, Milton J.; Itzstein, Mark von

doi:10.1021/ol035733d

Cited by 28 publications

(13 citation statements)

References 25 publications

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“…Previous report also suggest that a 4,6‐ O ‐benzylidene protection pattern plays a very important role in the synthesis of the 3‐thio‐β‐ D ‐galactose derivatives, with the key step involving the conversion of the 3‐OTf gulose derivative to the corresponding galactose derivatives 27,28. In addition, recent reports demonstrated that tetrabutylammonium thioacetate is a useful nucleophile in the successful synthesis of 3‐thiogalactose derivatives when esters were used as protecting groups 29,30.…”

Section: Resultsmentioning

confidence: 98%

Synthesis of Positional Thiol Analogs of β‐D‐Galactopyranose

et al. 2007

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Approaches toward the synthesis of thio‐β‐D‐galactose derivatives are described. These compounds were prepared from the parent carbohydrates: D‐galactose, methyl β‐D‐galactoside and methyl β‐D‐glucoside, respectively. It was found that not only the strategies of protecting group introduction and selective deprotection, but also the choices of solvent and nucleophilic reagent concentration were crucial to allow the efficient introduction of sulfur at different positions of the galactose ring. The effects from the solvent, the nucleophilic reagent concentration, and the protecting group patterns have been investigated. The results clearly show that ester protecting groups play highly important roles for the synthesis of thio‐containing carbohydrates, requiring nonpolar solvents to suppress the neighboring group participation. For the Lattrell–Dax (nitrite‐mediated) inversion reaction, employed in the synthetic route to the 2‐thio‐β‐D‐galactoside, intramolecular nucleophilic attack, as well as strongerstereospecific ester activation, are necessary to overcome hindrance from 4,6‐O‐benzylidene protection.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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Section: Resultsmentioning

confidence: 98%

Synthesis of Positional Thiol Analogs of β‐D‐Galactopyranose

et al. 2007

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“…High yielding inversions at C‐3 of gulopyranosides require protection of the 4,6‐diol as a cyclic acetal and are favoured by use of ester, rather than ether protecting groups at O‐2 42. 48 Two synthetic routes to substrates meeting these requirements were identified and are outlined in Scheme .…”

Section: Resultsmentioning

confidence: 99%

Chemical and Chemoenzymatic Synthesis of S‐Linked Ganglioside Analogues and Their Protein Conjugates for Use as Immunogens

Rich

Wakarchuk

Bundle

2006

Chemistry A European J

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Analogues of the tumor-associated gangliosides GM(3) and GM(2) containing terminal S-linked neuraminic acid residues and an amino terminated, truncated ceramide homologue have been synthesized and conjugated to a protein. The synthesis involved coupling of a S-linked sialyl alpha(2-->3) galactose disaccharide with a glucosyl sphingosine analogue, followed by elaboration and deprotection to give amino-terminated glycosyl ceramide 1. Glycosyltransferase-catalyzed extension of the trisaccharide 1 provided access to the modified GM(2) tetrasaccharide 2 or sulphur-containing GD(3) analogue 30. Owing to their potentially enhanced resistance to endogenous exo-glycoside hydrolases and their inherent non-self character, carbohydrate antigens containing non-reducing terminal thioglycosidic linkages may be more immunogenic than O-linked antigens and may stimulate the production of antibodies capable of recognizing naturally occurring oligosaccharides. Our initial results suggest that in fact these antigens are viable immunogens and furthermore, that immune sera cross reacts with O-gangliosides in the context of a heterologous glycoprotein conjugate.

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“…The possibility of direct one-step transformation of 22 to 24 by regioselective opening of 4′,6′-O-benzylidene acetal under oxidative conditions (dimethyldioxirane) 38 was not explored. There are a few methods [39][40][41] for the preparation of O-benzoylated lactosyl glycosides with a hydroxyl group at C-3′ including a recently proposed 42 approach for O-benzoylation of the axial hydroxy group in vicinal cis-diols. Diol 25, readily available from 20, was converted via intermediate formation of its orthoester into lactosyl acceptor 26 with the hydroxy group at C-3′.…”

Section: Figure 2 Galactosyl Acceptors 9-12mentioning

confidence: 99%

A Novel Glycosyl Donor with a Triisopropylsilyl Nonparticipating Group in Benzyl-Free Stereoselective 1,2-cis-Galactosylation

Abronina

Zinin

Malysheva

et al. 2017

Synlett

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A novel glycosyl donor with a triisopropylsilyl (TIPS) nonparticipating group at O-2 is introduced for use in 1,2-cis-galactosylation. Coupling the 2-O-TIPS-substituted thiogalactoside donor with a series of mono- and disaccharide glycosyl acceptors was found to lead exclusively to α-linked oligosaccharides. The observed exceptionally high α-selectivity was interpreted in terms of conformational changes in the glycosyl cation induced by the bulky 2-O-TIPS group.

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Synthesis of Lactose-Based S-Linked Sialylmimetics of α(2,3)-Sialosides

Cited by 28 publications

References 25 publications

Synthesis of Positional Thiol Analogs of β‐D‐Galactopyranose

Synthesis of Positional Thiol Analogs of β‐D‐Galactopyranose

Chemical and Chemoenzymatic Synthesis of S‐Linked Ganglioside Analogues and Their Protein Conjugates for Use as Immunogens

A Novel Glycosyl Donor with a Triisopropylsilyl Nonparticipating Group in Benzyl-Free Stereoselective 1,2-cis-Galactosylation

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