Stannylene‐Mediated Regioselective 6‐<i>O</i>‐Glycosylation of Unprotected Phenyl 1‐Thioglycopyranosides

Maggi, Agnese; Madsen, Robert

doi:10.1002/ejoc.201300026

Cited by 19 publications

(7 citation statements)

References 42 publications

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“…Madsen also used dibutyltin oxide in regioselective glycosylation of compound 58 on the unprotected acceptor 57 to form β‐(1–6)‐linked glycoside 59 (Scheme ). The best yield was obtained in the presence of AgOTf and 4Å MS as a desiccant and a very weak acid scavenger.…”

Section: Discussionmentioning

confidence: 99%

“…The selectivity for 53 is driven by the selective formation of the tin acetal of 52 at C-2 and C-3, and selective glycosylation at less hindered equatorial C-3 position. In 2003, Kaji [85] also demonstrated that the reactivity of different stannylenes could be influenced by adding a salt such as [86] Madsen [87] also used dibutyltin oxide in regioselective glycosylation of compound 58 on the unprotected acceptor 57 to form -(1-6)-linked glycoside 59 (Scheme 13). The best yield was obtained in the presence of AgOTf and 4Å MS as a desiccant and a very weak acid scavenger.…”

Section: Tin-mediated Glycosylation On Unprotected Acceptorsmentioning

confidence: 99%

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Glycosylation on Unprotected or Partially Protected Acceptors

Ding

Prasad²,

Wang

2020

Eur J Org Chem

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Over the last 30 years, there have been several methods developed for the synthesis of oligosaccharides, such as combinatorial synthesis, programmable one‐pot glycosylations, pre‐activation‐based chemo‐selective glycosylation strategy, random glycosylation, chemo‐enzymatic processes, and automated platforms. Distinguishing hydroxyl groups in carbohydrate monomers form the crux of oligosaccharides synthesis. The protection of hydroxyl groups stops glycosylation at undesired positions on carbohydrates, but additional steps are required to install and remove the protecting groups. The targeted functionalization of carbohydrates relies mostly on the protection of hydroxyl groups that are not supposed to undergo glycosylation and to leave the hydroxyl group unprotected where the glycosylation should occur. Numerous procedures to avoid or decrease protecting group manipulations have been developed for the synthesis of a single or an oligosaccharide library, such as glycosylation on unprotected or partially protected acceptors, and random glycosylation on unprotected acceptors. In this review, overall approaches for glycosylation on unprotected or partially protected acceptors in the synthesis of oligosaccharides and oligosaccharide libraries are summarized, the glycosylation on unprotected or partially protected carbohydrate acceptors with or without tin or boron mediation, and random glycosylation on unprotected or partially protected acceptors in solution phase or on solid phase are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Tin-mediated Glycosylation On Unprotected Acceptorsmentioning

confidence: 99%

Glycosylation on Unprotected or Partially Protected Acceptors

Ding

Prasad²,

Wang

2020

Eur J Org Chem

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“…Attempt to mimic such selectivity remains the grail for glycochemists. Already, regioselective glycosylation of naked acceptors could be performed thanks to transient selective activation of one hydroxyl group against the others using for example dibutyltin(IV) oxide , or aryl borinic acid , as inducers of regioselectivity. More recently, Taylor and co-workers developed new diarylborinic acid derivatives for the regioselective acylation, alkylation or tosylation of the secondary alcohol of various alkyl glycosides.…”

Section: Introductionmentioning

confidence: 99%

Regioselective Galactofuranosylation for the Synthesis of Disaccharide Patterns Found in Pathogenic Microorganisms

et al. 2017

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Koenigs-Knorr glycosylation of acceptors with more than one free hydroxyl group by 2,3,5,6-tetrabenzoyl galactofuranosyl bromide was performed using diphenylborinic acid 2-aminoethyl ester (DPBA) as inducer of regioselectivity. High regioselectivity for the glycosylation on the equatorial hydroxyl group of the acceptor was obtained thanks to the transient formation of a borinate adduct of the corresponding 1,2-cis diol. Nevertheless formation of orthoester byproducts hampered the efficiency of the method. Interestingly electron-withdrawing groups on O-6 or on C-1 of the acceptor displaced the reaction in favor of the desired galactofuranosyl containing disaccharide. The best yield was obtained for the furanosylation of p-nitrophenyl 6-O-acetyl mannopyranoside. Precursors of other disaccharides, found in the glycocalix of some pathogens, were synthesized according to the same protocol with yields ranging from 45 to 86%. This is a good alternative for the synthesis of biologically relevant glycoconjugates.

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“…A particular challenge would be to glycosylate the secondary alcohols in 2,3,4,6‐unprotected hexopyranosides, and for this reason we decided to explore the use of the cheaper phenylboronic acid as a transient blocking group. As in our recent study with dibutyltin oxide,12a phenyl 1‐thioglycopyranosides were chosen as acceptors, since the products of the regioselective couplings would then be thioglycoside building blocks, which are useful glycosyl donors in oligosaccharide synthesis. Thus, in this paper, we report full details of the regioselective glycosylation of unprotected thiohexopyranosides using an in situ blocking strategy with phenylboronic acid.…”

Section: Introductionmentioning

confidence: 99%

Regioselective Glycosylation of Unprotected Phenyl 1‐Thioglycopyranosides with Phenylboronic Acid as a Transient Masking Group

Fenger

Madsen

2013

Eur J Org Chem

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A useful protocol is described for the regioselective glycosylation of the secondary alcohols in unprotected glycosyl acceptors. Phenyl 1‐thioglycopyranosides derived from D‐glucose, D‐galactose, D‐glucosamine, L‐rhamnose, and L‐fucose were treated with phenylboronic acid to install a temporary boronic ester, and then submitted to a Koenigs–Knorr glycosylation with perbenzoylated glucopyranosyl or galactopyranosyl bromides. Good yields for coupling to the 3‐position in glucosides and galactosides were achieved, but lower yields were obtained with the other acceptors. With phenyl 1‐thio‐β‐D‐glucopyranoside, the coupling could also be achieved with a superarmed thiogalactoside donor. The product from a glucose–glucose coupling could be subjected to a second regioselective glycosylation at the 6‐position. In the galactose series, a β(1→3)‐linked galactotriose could be prepared in good yield by two consecutive glycosylations in one pot, where a free 2‐hydroxy group ensures neighboring group participation in the second coupling.

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Stannylene‐Mediated Regioselective 6‐O‐Glycosylation of Unprotected Phenyl 1‐Thioglycopyranosides

Cited by 19 publications

References 42 publications

Glycosylation on Unprotected or Partially Protected Acceptors

Glycosylation on Unprotected or Partially Protected Acceptors

Regioselective Galactofuranosylation for the Synthesis of Disaccharide Patterns Found in Pathogenic Microorganisms

Regioselective Glycosylation of Unprotected Phenyl 1‐Thioglycopyranosides with Phenylboronic Acid as a Transient Masking Group

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