A facile synthesis of the GalNAcβ1→4Gal target sequence of respiratory pathogens

Autar, Reshma; Liskamp, Rob M. J.; Pieters, Roland J.

doi:10.1016/j.carres.2005.08.001

Cited by 10 publications

(7 citation statements)

References 25 publications

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“…Acceptor 13 and the known thioglycoside donor 12 reacted in a β‐selective glycosylation under standard reaction conditions to give disaccharide 24 with 82 % yield . Surprisingly, the more reactive trichloroacetimidate donor provided disaccharide 24 in only 44 % yield.…”

Section: Figurementioning

confidence: 99%

“…Little is known about their biological activities. N-methylamino ester 7 was synthesised in three steps and 61 %y ield from commercially availableB oc-d-aspartic acid 4benzylester (14). [1c] The magnesium salt of ancorinoside A( 1)s howed identicala ctivities, [1b] contrary to widely held assumptions on the importance of metal chelation for the bioactivity.…”

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confidence: 99%

“…[10][11][12] Re-acetylation of 22 gave acetal 23 which,d eviating from the literature, [13] was selectively reduced with triethylsilane and trifluoroacetic acid (TFA) to afford buildingb lock 13 in 60 %y ield over five steps (Scheme 4). [12,14] Surprisingly, the more reactive trichloroacetimidate donor providedd isaccharide 24 in only 44 %y ield. [12,14] Surprisingly, the more reactive trichloroacetimidate donor providedd isaccharide 24 in only 44 %y ield.…”

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confidence: 99%

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Total Synthesis of the Diglycosidic Tetramic Acid Ancorinoside A

Petermichl

Schobert

2017

Chemistry A European J

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Ancorinoside A, a metabolite of a sponge Ancorina sp., was prepared in 18 steps as the first derivative of this class of glycosylated 3-acyltetramic acids. It features a β-d-glucopyranosyl-(1→4)-β-d-galacturonic acid linked to a d-aspartic acid derived tetramic acid via a 3-docosanoyl spacer. The diglycoside was built up by connecting the protected monosaccharides d-galactose and d-glucose via a thioglycoside glycosylation. Attachment of the spacer by a subsequent Schmidt glycosylation of this diglycoside, TEMPO oxidation to the uronic acid, functionalisation of the spacer terminus with an N-(β-ketoacyl)aspartate, and a final Dieckmann cyclisation were the key steps leading to ancorinoside A. This approach should also allow access to ancorinoside D.

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Section: Figurementioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Total Synthesis of the Diglycosidic Tetramic Acid Ancorinoside A

Petermichl

Schobert

2017

Chemistry A European J

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“…The group of Roland Pieters and co-workers has then reported two subsequent synthetic strategies towards GalNAc--(1→4)-Gal disaccharides functionalized with spacer arm at the reducing end with carboxylic acid or azide moieties for further conjugations. 18,19 Both strategies also reported the acetylated disaccharides which are therefore compatible with conjugations to several biomolecules or scaffolds in comparison to the benzylated precursors presented above requiring hydrogenolysis.…”

Section: Compound D) Into the Uncommon Galactosamine Through A 3-o-camentioning

confidence: 88%

“…A second approach was later reported improving slightly the synthetic steps for the preparation of the acceptor M which was obtained in 6 steps and 42% overall yield from galactose I. 18 The anomeric benzyl group was used in replacement of the temporary 2trimethylsilylethyl protecting group and acetates were used for the protection of the secondary positions while another benzyl ether was necessary at the 6-position. The glycosylation proceeded similarly at very low temperature and in higher yield (90%).…”

Section: Compound D) Into the Uncommon Galactosamine Through A 3-o-camentioning

confidence: 99%

Synthesis of 3-Azidopropyl-Functionalized GalNAc-β-(1→4)-Gal Natural Disaccharide

Lafont

Wang²,

Vidal³

2019

Preprint

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Oligosaccharides such as the GalNAc-β-(1→4)-Gal disaccharide are involved in host-pathogen interactions and their synthesis is a continuing challenge for organic chemists. Only a few reports have discussed the synthesis of functionalized GalNAc-β-(1→4)-Gal for its further conjugation and applications in glycobiology. The synthetic route described here is taking advantage of (1) a simple and affordable GlcNAc donor which is epimerized to the more expensive GalNAc donor and (2) a 1,6-anhydro-galactose acceptor exalting the reactivity at the 4-position of galactose. The allyloxycarbonyl (Alloc) protecting group used at the 2-position of the GalNAc residue was important (1) for a successful epimerization of the GlcNAc residue into the corresponding GalNAc donor but also (2) for the stereoselective β-glycosylation through anchimeric assistance. The key disaccharide intermediate was further transformed to a trichloroacetimidate donor which could then be glycosylated with any alcohol. The example chosen here is the 3-azidopropyl aglycon for the design of multivalent glycoclusters.<br>

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Regioselective Acetolysis of Highly O‐Benzylated Carbohydrates Promoted by Iodine or an Iodine/Silane Combined Reagent: Use of Isopropenyl Acetate as an Alternative to Acetic Anhydride

2013

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Regioselective acetolytic de‐O‐benzylation of poly‐O‐benzylated sugars can be triggered by the activation of isopropenyl acetate (IPA) with either an iodine/silane combined reagent or iodine alone. Unlike other known acetolysis procedures, the protocols presented here do not suffer from the use of harsh acidic reagents and excess amounts of high‐boiling acetic anhydride. The activation of IPA with iodine and triethylsilane (or the cheaper polymethylhydrosiloxane, PMHS) usually results in shorter reaction times, with the acetolysis occurring preferentially (with some exceptions) at primary benzyloxy groups. With anomerically armed sugars, anomeric iodination can be a concomitant process to give highly reactive intermediates which can be converted in situ into workable and useful building blocks upon suitable quenching conditions. On the other hand, IPA activation with iodine alone allows the reactions to occur under milder conditions, albeit over longer times. In almost all reported examples, IPA can be used in moderate excess (5 equiv.), but its employment as the solvent is crucial with an amino sugar model compound otherwise recalcitrant to any acetolytic modification. An additional advantage of these conditions lies in the unprecedented possibility of incorporating the acetolysis step into one‐pot synthetic sequences leading to multiple functional modifications of saccharidic substrates. As to the regioselectivity, most reactions seem to be controlled by steric factors, as the most accessible primary benzyloxy groups are commonly acetolyzed. However, a couple of disclosed examples display that under suitable structural conditions, strain relief effects might be a ruling factor for the regiocontrol of the processes. Overall, the reported protocols offer complementary options for experimentally easy access to a wide range of useful saccharide building blocks featuring a varied profile of protecting groups.

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A facile synthesis of the GalNAcβ1→4Gal target sequence of respiratory pathogens

Cited by 10 publications

References 25 publications

Total Synthesis of the Diglycosidic Tetramic Acid Ancorinoside A

Total Synthesis of the Diglycosidic Tetramic Acid Ancorinoside A

Synthesis of 3-Azidopropyl-Functionalized GalNAc-β-(1→4)-Gal Natural Disaccharide

Regioselective Acetolysis of Highly O‐Benzylated Carbohydrates Promoted by Iodine or an Iodine/Silane Combined Reagent: Use of Isopropenyl Acetate as an Alternative to Acetic Anhydride

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