- Facile synthesis of sugar lactols via bromine-mediated oxidation of thioglycosides
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Synthesis of a variety of sugar lactols (hemiacetals) has been accomplished in moderate to excellent yields by using bromine-mediated oxidation of thioglycosides. It was found that acetonitrile is the optimal solvent for this oxidation reaction. This approach involving bromine as oxidant is superior to that using N-bromosuccinimide (NBS) which produces byproduct succinimide often difficult to separate from the lactol products.
- Meng, Shuai,Bhetuwal, Bishwa Raj,Acharya, Padam P.,Zhu, Jianglong
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p. 109 - 126
(2019/03/26)
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- Tetranuclear zinc cluster: A dual purpose catalyst for per-: O -acetylation and de- O -acetylation of carbohydrates
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The trifluoroacetic acid adduct of tetranuclear zinc cluster Zn4(OCOCF3)6O catalysis in per-O-acetylation and de-O-acetylation of carbohydrates at 70 °C can be tuned by adjusting the reaction medium. Per-O-acetylation of hexopyranoses with a near stoichiometric amount of acetic anhydride in toluene resulted in the exclusive formation of pyranosyl products as an anomeric mixture, whereas de-O-acetylation of acetates occurred in methanol in high yields. In the latter, methanol acts as both nucleophile and solvent, and the reaction conditions were compatible to acid- and base-sensitive groups and amino acid derivatives.
- Lin, Ting-Wei,Adak, Avijit K.,Lin, Hong-Jyune,Das, Anindya,Hsiao, Wei-Chen,Kuan, Ting-Chun,Lin, Chun-Cheng
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p. 58749 - 58754
(2016/07/07)
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- An efficient synthesis of C3 C-alkylated Neu5Ac2en derivatives
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C3-modified Neu5Ac2en derivatives can be used to study the flexible 150-loop region of influenza virus sialidases and also provide a new template for the development of next-generation sialidase inhibitors. This Letter describes an efficient synthetic route towards the large scale synthesis of C3 C-alkylated Neu5Ac2en derivatives. The key intermediate, a 3-eq-allyl-Neu5Ac derivative, is formed by stereoselective addition of the allyl group in an equatorial configuration at C3, regardless of the stereochemistry of the bromohydrin precursor.
- Rudrawar, Santosh,Pascolutti, Mauro,Bhatt, Beenu,Thomson, Robin J.,Von Itzstein, Mark
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supporting information
p. 1198 - 1201
(2013/03/14)
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- Chemical Synthesis and Enzymatic Testing of CMP-Sialic Acid Derivatives
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The cycloSal approach has been used in the past for the synthesis of a range of phosphorylated bioconjugates. In those reports, cycloSal nucleotides were allowed to react with different phosphate nucleophiles. With glycopyranosyl phosphates as nucleophile
- Wolf, Saskia,Warnecke, Svenja,Ehrit, Joerg,Freiberger, Friedrich,Gerardy-Schahn, Rita,Meier, Chris
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p. 2605 - 2615
(2013/01/16)
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- NOVEL GLYCOSYL PHOSPHITES
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The present invention relates to providing compounds of general formula (1) wherein A is glycosyl residue of a mono-, di- or oligosaccharide in protected form and R is selected from optionally substituted aryl or optionally substituted heteroaryl, methods
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- PRODUCTION OF 6'-O-SIALYLLACTOSE AND INTERMEDIATES
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The present invention relates to a method for preparation of the trisaccharide 6'-0-sialyllactose (formula (I)) or salts thereof as well as intermediates in the synthesis and for the use of 6'-0-sialyllactose salts in pharmaceutical or nutritional composi
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- Toward fully synthetic homogeneous β -human Follicle-Stimulating hormone (β -hFSH) with a biantennary N-linked dodecasaccharide. synthesis of β -hFSH with chitobiose units at the natural linkage sites
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A highly convergent synthesis of the sialic acid-rich biantennary N-linked glycan found in human glycoprotein hormones and its use in the synthesis of a fragment derived from the β -domain of human Follicle-Stimulating Hormone (hFSH) are described. The synthesis highlights the use of the Sinay radical glycosidation protocol for the simultaneous installation of both biantennary side-chains of the dodecasaccharide as well as the use of glycal chemistry to construct the tetrasaccharide core in an efficient manner. The synthetic glycan was used to prepare the glycosylated 20-27aa domain of the β -subunit of hFSH under a Lansbury aspartylation protocol. The proposed strategy for incorporating the prepared N-linked dodecasaccharide-containing 20-27aa domain into β -hFSH subunit was validated in the context of a model system, providing protected β -hFSH subunit functionalized with chitobiose at positions 7 and24.
- Nagorny, Pavel,Fasching, Bernhard,Li, Xuechen,Chen, Gong,Aussedat, Baptiste,Danishefsky, Samuel J.
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supporting information; experimental part
p. 5792 - 5799
(2009/09/24)
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- Versatile acetylation of carbohydrate substrates with bench-top sulfonic acids and application to one-pot syntheses of peracetylated thioglycosides
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Inexpensive and readily available sulfonic acids, p-toluenesulfonic acid, and sulfuric acid are versatile and efficient catalysts for the peracetylation of a broad spectrum of carbohydrate substrates in good yield and in a practical time frame. Three appealing features in sulfonic acid-catalyzed acetylation of free sugars were explored including (1) suppression of furanosyl acetate formation for d-galactose and l-fucose; (2) high yielding chemoselective acetylation of sialic acid under appropriate conditions; and (3) peracetylation of amino sugars with different amino protecting functions. Simple one-pot two step acetylation-thioglycosidation methods for the expeditious synthesis of p-tolyl per-O-acetyl thioglycosides were also delineated.
- Chao, Chin-Sheng,Chen, Min-Chun,Lin, Shih-Che,Mong, Kwok-Kong T.
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p. 957 - 964
(2008/09/17)
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- Highly efficient α-sialylation by virtue of fixed dipole effects of N-phthalyl group: Application to continuous flow synthesis of α(2-3)-and α(2-6)-Neu5Ac-Gal motifs by microreactor
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Highly α-selective sialylation of sialic acid N- phenyltrifluoroacetimidate with various galactose and lactose acceptors has been achieved by introducing the C-5 N-phthalyl group on the donor. The "fixed dipole effect" of the N-phthalyl group was proposed to explain the high reactivity and α-selectivity. The microfluidic system was applied to the present α-sialylation, which is amenable to large-scale synthesis. The N-phthalyl group was removed by treatment with methylhydrazine acetate, for which protocol can be readily applied to the synthesis of a variety of sialic acid-containing oligosaccharides. (Chemical Equation Presented). Copyright Taylor & Francis Group, LLC.
- Tanaka, Shin-Ichi,Goi, Takashi,Tanaka, Katsunori,Fukase, Koichi
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p. 369 - 394
(2008/04/12)
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- Large-scale synthesis of per-O-acetylated saccharides and their sequential transformation to glycosyl bromides and thioglycosides
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This work describes a large-scale synthesis of per- O -acetylated mono- and disaccharides using a stoichiometric amount of acetic anhydride in the presence of LiClO 4 under solvent-free conditions. The peracetylated saccharides underwent subsequent anomeric bromination and thioglycosidation in one-pot to yield synthetically valuable building blocks. Copyright Taylor & Francis Group, LLC.
- Lin, Chan-Ching,Huang, Li-Cheng,Liang, Pi-Hui,Liu, Ching-Yang,Lin, Chun-Cheng
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p. 303 - 313
(2007/10/03)
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- Synthesis and Characterization of an Anomeric Sulfur Analogue of CMP-Sialic Acid
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α-2,3-Sialyltransferase catalyzes the transfer of sialic acid from CMP-sialic acid (1) to a lactose acceptor. An analogue of 1 was synthesized in which the anomeric oxygen atom was replaced with a sulfur atom (1S). The key step in the synthesis of IS was a tetrazole-promoted coupling of a cytidine-5′-phosphoramidite with a glycosyl thiol of a protected sialic acid. Compounds 1 and 1S were characterized for their activity in a sialyl transfer assay. The rate of solvolysis in aqueous buffer of analogue 1S was 50-fold slower than that of 1. Analogue 1S was found to be substrate for α-2,3-sialyltransferase. The Km of 1S was just 3-fold higher than that of 1, while the kcat of 1S was 2 orders of magnitude lower compared to 1.
- Cohen, Scott B.,Halcomb, Randall L.
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p. 6145 - 6152
(2007/10/03)
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- The total synthesis of ganglioside GM3
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Previous syntheses of ganglioside GM3 (NeuAcα3Galβ4Glcβ1Cer) are reviewed, and both chemoenzymatic and chemical total synthetic approaches were investigated. In a chemoenzymatic approach, (2S,3R,4E)-5'''-acetyl-α-neuraminyl-(2''' → 3'')-β-galactopyranosyl-(1'' → 4')-β-glucopyranosyl-(1' mutually implies 1)-2-azido-4-octadecene-1,3-diol (azidoGM3) was readily prepared utilizing recombinant β-Gal-(1'' → 3'/4')-GlcNAc α-(2''' → 3'')-sialyltransferase enzyme, and was evaluated as a synthetic intermediate to ganglioside GM3. The chemical total synthesis of ganglioside GM3 was performed on one of the largest scales yet reported. The highlights of this synthesis include minimizing the steps necessary to prepare the lactosyl acceptor as a useful anomeric mixture, which was present in excess for the highly regioselective and fairly stereoselective sialylation with a known neuraminyl donor to give the protected GM3 trisaccharide. The synthetic methodology maximized convergence by a subsequent glycosidic coupling of the well-characterized GM3 trisaccharide trichloroacetimidate derivative with protected ceramide. The ganglioside GM3 was nearly homogeneous as the two glycosidic couplings utilized preparative HLPC purifications, and variations in the sphingosine base and fatty acyl group were under 0.1 and 0.2%, respectively. (C) 2000 Elsevier Science Ltd.
- Duclos Jr., Richard I.
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p. 489 - 507
(2007/10/03)
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- Iodine : A versatile reagent in carbohydrate chemistry IV. Per-O-Acetylation, regioselective acylation and acetolysis
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Iodine has been found to be an effective Lewis acid for promoting the per-O-acetylation of unprotected sugars. Under controlled conditions it can bring about regioselective acylation of carbohydrate derivatives. At higher concentration and with longer reaction times, iodine can effect the selective acetolysis of benzyl ether-protected primary hydroxyl groups. All of these reactions proceed in high yield, are easy to carry out and make use of readily available iodine, which is both cheap and easy to handle.
- Kartha, K. P. Ravindranathan,Field, Robert A.
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p. 11753 - 11766
(2007/10/03)
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- Chemical and enzymatic synthesis of high-affinity selectin ligands
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Analogs of sialyl Lewis(X) have been synthesized chemically using donors of modified sialic acids. The sialic acids were obtained enzymatically by an aldolase reaction. The sLe(x) tetrasaccharides modified at C-2 of the GlcNAc moiety and at C-5 of the sialic acid residue were tested as inhibitors for E- and P-selectins. Up to 12-fold higher inhibitory potency was found for the lyso-derivative of sLeX compared to the parent compound.
- Kuznik,Hoersch,Kretzschmar,Unverzagt
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p. 577 - 580
(2007/10/03)
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- Synthesis of CMP-sialic acid conjugates: Substrates for the enzymatic synthesis of natural and designed sialyl oligosaccharides
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The syntheses of several congeners of CMP-NeuAc are described. These compounds are substrates for enzymatic glycosylation.
- Chappell, Mark D.,Halcomb, Randall L.
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p. 11109 - 11120
(2007/10/03)
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- Synthesis of α-N-Ketosides of N-Acetylneuraminic Acid by Using Phase-Transfer Catalysis
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α-N-Ketosides of N-acetylneuraminic acid (Neu5Ac) can be synthesized by using azide and thiocyanate salt as aglycone under conditions of phase-transfer catalysis (PTC).The catalytic hydrogenation of the 2-α-azido ketoside 3 leads to the 2-α-amino ketoside
- Rothermel, Joerg,Weber, Bernd,Faillard, Hans
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p. 799 - 802
(2007/10/02)
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- Reinvestigation of the synthesis of 4-methylcoumarin-7-yl 5-acetamido-3,5-dideoxy-alpha-D-glycero-D-galacto-2-nonulopyranosidonic acid, a fluorogenic substrate for neuraminidase.
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A crystalline tetrabutylammonium salt of 7-hydroxy-4-methylcoumarin was prepared and shown to contain two coumarin residues for each ammonium group. Condensation of this salt with the glycosyl chloride of methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-beta-D-glycero-D-galacto-2-nonulopyranosonate in dry acetonitrile at room temperature gave the corresponding alpha-glycoside in higher yield and purity than previously reported methods. Removal of the acetyl and methyl ester blocking-groups gave the free glycoside, which was shown to have the alpha configuration by n.m.r. spectroscopy. In contrast, the reaction of the free coumarin derivative with the chloro sugar in refluxing, dry toluene in the presence of cadmium carbonate as acid acceptor gave none of the above glycoside, but gave the corresponding glycal in good yield.
- Baggett,Marsden
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