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Abstract: Ethyl 6-O-acetyl-2,3,4-tribenzyl-1-thio-d-glucopyranoside, as a mixture of anomers, was employed for the stereoselective synthesis of the potassium salt of (2R)-2-O-α-d-glucopyranosyl-(1→6)-α-d-glucopyranosyl-2,3-dihydroxypropanoic acid (α-d-glucosyl-(1→6)-α-d-glucosyl-(1→2)-d-glyceric acid, GGG), a recently isolated compatible solute. The α-anomer was by far the major product of both glycosylation reactions using NIS/TfOH as activator. [Copyright &y& Elsevier]

Abstract: The recently described [Attolino, E.; Bonaccorsi, F.; Catelani, G.; D’Andrea, F. Carbohydr. Res. 2008, 343, 2545–2556.] β-d-MaNAcp-(1→4)-β-d-Glcp thiophenyl glycosyl donor 3 was used in α-glycosylation reactions of OH-2 and OH-3 of the suitably protected p-MeO-benzyl α-l-rhamnopyranoside acceptors 7 and 8. Glycosylation of the axial OH-2 of 7 took place in high yield (76%) and with acceptable stereoselectivity (α/β=3.4) leading to the protected trisaccharide α-11, corresponding to the repeating unit of Streptococcus pneumoniae 19F. The same reaction on equatorial OH-3 of acceptor 8 gave the trisaccharide α-15, a constituent of the repeating unit of S. pneumoniae 19A, but in lower yield (41%) and without stereoselection (α/β=1:1.3). Utilizing the introduced orthogonal protection of OH-1 and OH-4″, the trisaccharide α-11 was transformed into a trisaccharide building block suitable for the synthesis of its phosphorylated oligomers. [Copyright &y& Elsevier]

Abstract: In order to develop novel influenza sialidase inhibitors, we constructed a library of glycoclusters composed of twelve types of sialylated dendrimers with thioglycosidic linkage that are resistant to hydrolysis by the sialidases. These sialodendrimers were synthesized by condensation reaction between a thiosialoside modified on the aglycon terminal end by a thioacetyl group and twelve types of carbosilane dendrimers having brominated terminal ends under deacetylation conditions, and temporal re-protection was performed for purification. Removal of all protection of the glycodendrimers was accomplished by transesterification and subsequent saponification to provide corresponding water-soluble glycodendrimers in good yields. For investigation of the structure–activity relationship, dendrimer scaffolds having differences in number of the sugar moieties, such as 3-, 4-, 6- and 12-functionalized dendrimers, and in linkage patterns, such as normal aliphatic linkage, ether- and amide-linkages. Biological evaluations of these glycodendrimers showed that all of the ether- and amide-elongated compounds had inhibitory potencies for the influenza sialidases in the mM range, while compounds having normal aliphatic linkage did not have any activities except for a 12-functionalized compound. [Copyright &y& Elsevier]

Six new thioglycosides incorporating the 4,5-diphenyl- and 3,4,5-triphenylimidazole moiety have been successfully synthesized under both conventional and microwave conditions by reaction of the corresponding thiones with aceto-bromosugars in presence of triethylamine as base. Attempted preparation of the bis(glycosyl) derivatives from 4,5-diphenylimidazole-2-thione in the presence of different bases was unsuccessful. Evaluation of the glycosylthioimidazoles as disarmed donors has been investigated using different promoters; NBS/TMSOTf has been found to be an effective promoter for the activation of the anomeric center towards glycosylation reaction. [ABSTRACT FROM AUTHOR]

A series of 1,4-naphthoquinone O-acetylthioglycosides have been synthesized by the condensation of fully O-acetylated derivatives of 1-thio- d-xylose, 1-thio-L-arabinose, 1-thio- d-galactose, 1-thio- d-mannose, and 1-thiomaltose with 3-chloro-2-methoxy-1,4-naphtho-quinone. Their deacetylation with MeONa/MeOH proceeded with simultaneous heterocyclization to yield linear carbohydrate-containing tetracyclic quinones. Tetracycles with trans junction of the carbohydrate and quinone rings are poorly soluble in water and organic solvents. [ABSTRACT FROM AUTHOR]

Abstract: A series of β-arabino glycosyl sulfones with varying alkyl chain lengths were synthesised in a stereoselective fashion as putative mimics of decaprenolphosphoarabinose (DPA), and as potential inhibitors of mycobacterial cell wall biosynthesis. Biological testing against Mycobacterium bovis BCG revealed low to moderate anti-mycobacterial activity with marked dependence on alkyl chain length, which was maximal for a C-12 chain. [Copyright &y& Elsevier]

Some new thiopyrimidine acyclic nucleosides and thioglycoside derivatives 3a-c, 4a-c, 6a,b, and 7a,b were synthesized. The cytotoxicity and antitumor evaluation of all prepared compounds have been tested in vitro against Ehrlich's ascites carcinoma cell line and their activity against glutathione peroxidase and catalase were reported. The role of the prepared compounds as free radical regulators and the therapeutic antitumor effect of a balanced generation of free radicals are discussed. Compounds 2, 3b, 3c, 4a, and 4c inhibited significantly in a dose dependent manner the growth of Ehrlich ascites carcinoma cells while the other compounds did not show any antitumor activity even at higher concentrations. [ABSTRACT FROM AUTHOR]

Abstract: An efficient separation between fully acetylated thiosialoside methyl esters and fully acetylated Neu5Ac2en methyl esters was accomplished by means of a size-exclusion chromatography (SEC) method. Purity determinations and structural elucidation of the isolated compounds were performed by a combination of elemental analyses and spectroscopic analyses, including IR, 1H, and 13C NMR, and mass spectroscopic analyses. [Copyright &y& Elsevier]

The thioglycoside of Neu5Gc unit was synthesized from the Neu5Ac derivative in 4 steps. The thioglycoside of Neu5Gc as a glycosyl donor was allowed to react with various alcohols to afford the corresponding glycosides. [Display omitted] • A Neu5Gc unit was prepared from a Neu5Ac derivative. • Thioglycoside of Neu5Gc was synthesized as a glycosyl donor. • Glycosidation of the Neu5Gc derivative gave the desired Neu5Gc-related compound. • Reaction properties of the thioglycoside of Neu5Gc were investigated. Efficient synthesis of lauryl thioglycoside of Neu5Gc was accomplished from a known thioglycoside of Neu5Ac. The reactivities of the Neu5Gc thioglycoside for O -glycosidation by means of TMSOTf-NIS as a promoter system were investigated, and the thioglycoside showed good activities with simple alcohols. In addition to the simple alcohols, the reactivities of lauryl thioglycoside of Neu5Gc were also evaluated with glucose and lactose derivatives and the results suggested that the thioglycoside is a potential candidate for glycosidation as the glycosyl donor. [ABSTRACT FROM AUTHOR]

Abstract: An alternative pathway to glucuronic acid-containing di- and trisaccharide thioglycoside building blocks, suitable for the synthesis of Cryptococcus neoformans capsular polysaccharide structures, has been developed. As opposed to our earlier synthesis, this approach features the introduction of the glucuronic acid motif at the di- and trisaccharide level through oxidation of a glucose residue. This approach circumvents problems encountered in glycosylations with glucuronic acid donors and benzylation of glucuronic acid-containing derivatives. Selective protection of primary alcohols was obtained at the di- and trisaccharide stage using TBDMS or trityl protecting groups, respectively. After benzylation of the secondary hydroxyl groups and subsequent removal of the TBDMS or trityl group, oxidation of the free primary alcohols to carboxylic acids was performed in high yield using the TEMPO–BAIB reagent mixture, which does not tend to oxidize thioglycosides. The new approach requires a number of extra steps, but has proven to be more reliable and easily reproducible. [Copyright &y& Elsevier]

N-Arylaminomethyl-3H-1,3,4-oxadiazole-2-thiones 2a,b were prepared from the corresponding N-arylglycinoylhydrazides. A number of their thioglycoside derivatives 4-7a-c and S-functionalized analogs 8-11a,b were synthesized by the reaction with different acetobromosugars and acyclic hydroxyalkylating agents. The antiviral activity of a number of the synthesized compounds against herpes simplex virus type 1 (HSV-1) and hepatitis A virus (HAV) was evaluated. Compounds 5a and 5b showed promising results against HAV. [ABSTRACT FROM AUTHOR]

Abstract: A fast, complete and clean conversion of thioglycosides into glycosyl sulfones under mild acidic conditions is described, using the HOF·CH3CN complex at room temperature. This methodology affords glycosyl sulfones in high yields and in excellent purity. [Copyright &y& Elsevier]

Abstract: Efficient preparations of thioglycoside derivatives of l-idose and l-iduronic acid are described. The method avoids the tedious chromatographic separations of furanose and pyranose anomeric mixtures, and affords the thioglycosides in a stereoselective manner. The l-idose and l-iduronic acid thioglycosides having combinations of different protecting groups proved to be efficient glycosyl donors in the synthesis of heparin disaccharides. [Copyright &y& Elsevier]

Abstract: Synthesis of 2-deoxy-d-arabino/lyxo-hexopyranosyl disaccharides is reported. In these, the disaccharides contain 2-deoxy-arabino-hexopyranosyl and 2-deoxy-lyxo-hexopyranosyl sugars as either the reducing or the non-reducing or both the sugar units of the disaccharides. The activated 2-deoxy-1-thioglycosides served as the common precursors to prepare the 2-deoxy disaccharides with the above configurations. [Copyright &y& Elsevier]

Abstract: Thioglycosides are valuable tools for complex oligosaccharides'' constructions. They present precious advantages due to their stability and crystalline nature. However, their major drawbacks are the repulsive smell of thiols utilised as precursors and, often, their toxicity such as in case of the commonly employed thiophenol and thioethanol. The use of commercially available methyl tert-butyl phenyl thiol (MbpSH) avoids these problems and is compatible with gram scale synthesis of thioglycoside donors. In this paper, we describe that Mbp thioglycosides are useful and convenient precursors for odourless oligosaccharide synthesis and we further demonstrate, as a proof of their versatility, their use in the construction of most of the glycosidic linkages found in N-glycans. [Copyright &y& Elsevier]

Abstract: The iminosugar thioglycosides are used as glycosyl donors in glycosidation reactions. Thereby, iminosugar glycosides and disaccharide analogues with an iminosugar moiety are prepared. The yields are high and the method is stereoselective. [Copyright &y& Elsevier]

Abstract: The syntheses of 4-nitrophenyl β-glycosides of the 3-thio and 4-thio analogues of the two principal 2-acetamido-2-deoxy-hexoses found in living systems, GlcNAc and GalNAc, are described. While synthesis of the 4-thio analogues could be achieved via nucleophilic displacements of sulfonate derivatives with thioacetate, problems with neighbouring group acetamido participation necessitated the use of sulfamidate intermediates for the 3-thio analogues. These 3- and 4-thio analogues are employed in the chemo-enzymatic synthesis of thio-oligosaccharide analogues of structures present in glycosaminoglycans, glycoproteins and glycolipids. [Copyright &y& Elsevier]

Abstract: Sweet almond β-glucosidase (EC 3.2.1.21) has been shown to have significant thioglycohydrolase activity. While the K m values for the S- and O-glycosides are similar, the k cat values are about 1000-times lower for the S-glycosides. Remarkably, the pH-profile for k cat/K m for hydrolysis of p-nitrophenyl thioglucoside (pNPSG) shows the identical dependence on a deprotonated carboxylate (pK a 4.5) and a protonated group (pK a 6.7) as does the pH-profile for hydrolysis of the corresponding O-glycoside. Not surprisingly, in spite of the requirement for the presence of this protonated group in catalytically active β-glucosidase, thioglucoside hydrolysis does not involve general acid catalysis. There is no solvent kinetic isotope effect on the enzyme-catalyzed hydrolysis of pNPSG. [Copyright &y& Elsevier]

Abstract: The synthesis of either anomers of aryl 2-deoxy-d-glycopyranosides from 2-deoxy-1-thioglycosides is reported. The α-anomers form as the major product when thioglycosides react with differently substituted phenols and naphthols, in the presence of N-iodosuccinimide/triflic acid. On the other hand, reaction of the thioglycosides with bromine initially, followed by reaction with aryloxy anions lead to aryl 2-deoxy-β-d-glycosides with high specificities. [Copyright &y& Elsevier]

Abstract: A conventional synthesis of α-thioglycoside of sialic acid as a glycomonomer was accomplished. Radical copolymerization of the glycomonomer with vinyl acetate proceeded smoothly to afford a new class of glycopolymers having thiosialoside residues, in which all protection was removed by a combination of transesterification and saponification to provide a water-soluble thiosialoside cluster. The results of a preliminary study on biological responses against influenza virus neuraminidases using the thiosialoside polymer as a candidate for a neuraminidase inhibitor showed that the glycopolymer has potent inhibitory activity against the neuraminidases. [Copyright &y& Elsevier]

Abstract: An N-dansyl-labeled K30 antigen repeating unit, {4-[5-(N,N′-dimethylamino)naphthalene-1-sulfonamine]-1H-1,2,3-triazol-1-yl}hexyl β-d-glucopyranosyluronate-(1→3)-α-d-galactopyranosyl-α-d-mannopyranosyl-(1→3)-β-d-galactopyranoside, was synthesized using click chemistry, the copper(I)-catalyzed 1,3-dipolar cycloaddition reaction of an azide and an alkyne. The target compound could further facilitate the studies of interactions among K30 oligosaccharides and proteins. [Copyright &y& Elsevier]

A general, odorless, one-pot methodology has been developed for the preparation of 1,2-trans-thioglycosides and thio-Michael addition products of carbohydrate derivatives through triphenyl phosphine-mediated cleavage of disulfides and reaction of the thiolate formed in situ with glycosyl bromides and glycosyl conjugated alkenes. [ABSTRACT FROM AUTHOR]

Abstract: An efficient synthesis of a series of carbosilane dendrimers uniformly functionalized with α-thioglycoside of sialic acid was accomplished. The results of a preliminary study on biological responses against influenza virus sialidases using thiosialoside clusters showed that some of the glycodendrimers have inhibitory potencies against the sialidases. [Copyright &y& Elsevier]

Abstract: Gallium(III) chloride catalyzes efficiently the addition of thiols to glycals under extremely mild conditions to afford 2-deoxy thioglycosides in high yields with a good α-selectivity. The reactions proceed rapidly at ambient temperature. [Copyright &y& Elsevier]

Abstract: p-Octyloxybenzenethiol (2) was synthesized as a new odorless benzenethiol. Moreover, preparation of thioglycosides using 2 and their application for glycosylation reactions were attempted. As a result, it was found that the thioglycosides were as excellent glycosyl donors as 4-dodecylphenyl 1-thio-glycosides, which were previously reported by our group, and more useful than the previous donors in terms of fine chemistry in glycosylation reaction activated with silver triflate and N-iodosuccinimide (NIS). In addition, this method was applicable to the sialylation with NIS and triflic acid. All procedures from the preparation of thioglycosides to the glycosylation reaction could be attained completely under conditions where no malodor was generated. [Copyright &y& Elsevier]

A simple and efficient procedure for the synthesis of thioglycosides has been achieved from the reaction of glycosylisothiouronium salts with alkyl or heteroaryl halides under microwave irradiation, in much shorter times and in yields comparable with conventional methods. [ABSTRACT FROM AUTHOR]

Abstract: The identity of the acid/base catalyst of the Family 35 β-galactosidases from Xanthomonas manihotis (BgaX) has been confirmed as Glu184 by kinetic analysis of mutants modified at that position. The Glu184Ala mutant of BgaX is shown to function as an efficient thioglycoligase, which synthesises thiogalactosides with linkages to the 3 and 4 positions of glucosides and galactosides in high (>80%) yields. Kinetic analysis of the thioglycoligase reveals glycosyl donor K m values of 1.5–21μM and glycosyl acceptor K m values from 180 to 500μM. This mutant should be a valuable catalyst for the synthesis of metabolically stable analogues of this important glycosidic linkage. [Copyright &y& Elsevier]

An unprecedented conversion of thioallcyl/aryl glycoside to the corresponding 1-O-acetates has been described using acetic anhydride and HClO4-SiO2 at rt. Although this transformation does not play an important role in the oligosaccharide synthesis in comparison to its reverse transformation, this gives useful information in selecting the reaction condition for the synthesis of oligosaccharides. The yields were excellent in all cases. [ABSTRACT FROM AUTHOR]

Abstract: A variety of thioglycosides are chemoselectively hydrolyzed to the corresponding 1-hydroxy glycosides using equimolar amounts of NIS/TFA as promoter systems. [Copyright &y& Elsevier]

Abstract: The synthesis of the tetrasaccharide α-d-Glcp-(1→2)-α-d-Glcp-(1→3)-α-d-Glcp-(1→3)-α-d-Manp-OMe, corresponding to the terminal tetrasaccharide portion of the glucose terminated arm of the N-glycan tetradecasaccharide, was achieved with complete stereocontrol by the use of iterative allyl protecting group mediated intramolecular aglycon delivery (allyl IAD) demonstrating the utility of intramolecular glycosylation for the stereocontrolled construction of multiple glycosidic linkages during the synthesis of an oligosaccharide. [Copyright &y& Elsevier]

Solid‐phase synthesis of sialyl Tn [α‐Neu5Ac‐(2→6)‐α‐GalNAc‐(1→ O )‐Ser] antigen with Kenner's acylsulfonamide linker is described. The acylsulfonamide bond was found to be stable under glycosylation reactions using dimethyl(methylthio)sulfonium triflate (DMTST) as a promoter and basic conditions used for the removal of protecting groups. The solid‐phase reaction was monitored by the inverse gated decoupling 13 C NMR technique, which enabled quantitative analysis of the reaction progress. At the end of the synthesis, the sulfamyl group of the linker was activated by treatment with (trimethylsilyl)diazomethane to provide a N ‐methyl‐ N ‐acylsulfonamide. The acyl group was displaced with hydroxide to give the corresponding precursors of sialyl Tn antigen and its anomeric isomers, which were deprotected to afford the target molecules. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: A rapid oxidation of thioglycosides to glycosyl sulfones has been achieved using a combination of KMnO4 and CuSO4·5H2O in acetonitrile and water. This reaction protocol has many advantages compared to other methods available for this transformation, including compatibility with acid and base labile functional groups used for the protection of carbohydrates, high yields, fast reaction times, and moderate reaction temperatures. The yields obtained were excellent in all cases. [Copyright &y& Elsevier]

Abstract: A convenient odorless methodology has been devised for the preparation of 1,2-trans-thio- and selenoglycosides through zinc-mediated cleavage of disulfides and diselenides and reaction of the thiolate and selenides formed in situ with glycosyl bromides. The yields were excellent in all cases. [Copyright &y& Elsevier]

Abstract: A C 3-symmetric (1→6)-N-acetyl-β-d-glucosamine octadecasaccharide was convergently synthesized on the basis of a copper(I)-catalyzed 1,3-dipolar cycloaddition reaction of azide and alkyne. The target octadecasaccharide showed good antitumor activity against H22 in the preliminary mice tests. [Copyright &y& Elsevier]

Abstract: p-Octyloxyphenylmethanethiol and p-dodecylbenzenethiol were prepared as new odorless organosulfur reagents. Thiosugars and thioglycosides were synthesized using these reagents without encountering any malodorous procedures. [Copyright &y& Elsevier]

An efficient one‐pot protocol for the direct preparation of thioglycosides starting from unprotected reducing sugars via S ‐glycosyl isothiouronium salts is reported. In this one‐pot methodology, BF 3 · OEt 2 has been used as a general catalyst for both per‐ O ‐acetylation of sugars and conversion of sugar per‐ O ‐acetates into S ‐glycosyl isothiouronium salts, which was allowed to react with alkylating agents in the presence of a base to furnish thioglycosides in excellent yield. [ABSTRACT FROM AUTHOR]

Abstract: A sequential per-O-acetylation and thioglycosidation of unprotected reducing sugars using a stoichiometric quantity of acetic anhydride and alkyl- or arylthiols is reported. These reactions, which are catalyzed by BF3·OEt2, together constitute an efficient one-pot method for the synthesis of acetylated thioglycosides. [Copyright &y& Elsevier]

The synthesis of two oligosaccharide fragments (1 and 2) of the lipoarabinomannan from Rhodococcus ruber is reported. Thioglycoside donors were used to assemble these glycans, which were prepared as their 8‐(methoxycarbonyl)octyl glycosides for potential incorporation into neoglycoconjugates. [ABSTRACT FROM AUTHOR]

An array of synthons is required to access an oligosaccharide library; however, multistep and thus time-consuming synthesis is inevitable. To rapidly access such synthetic units, multiple benzylation reactions of monosaccharides under phase-transfer conditions were examined. Multiple benzyl groups were successfully incorporated in one step, especially in the cases of reactions with triol systems. [ABSTRACT FROM AUTHOR]

Glucosinolates are a class of secondary metabolites with important roles in plant defense and human nutrition. Here, we characterize a putative UDP-glucose:thiohydroximateS-glucosyltransferase, UGT74B1, to determine its role in the Arabidopsis glucosinolate pathway. Biochemical analyses demonstrate that recombinant UGT74B1 specifically glucosylates the thiohydroximate functional group. LowKm values for phenylacetothiohydroximic acid (approximately 6 μm) and UDP-glucose (approximately 50 μm) strongly suggest that thiohydroximates arein vivosubstrates of UGT74B1. Insertional loss-of-functionugt74b1mutants exhibit significantly decreased, but not abolished, glucosinolate accumulation. In addition,ugt74b1mutants display phenotypes reminiscent of auxin overproduction, such as epinastic cotyledons, elongated hypocotyls in light-grown plants, excess adventitious rooting and incomplete leaf vascularization. Indeed, during early plant development, mutantugt74b1seedlings accumulate nearly threefold more indole-3-acetic acid than the wild type. Other phenotypes, however, such as chlorosis along the leaf veins, are likely caused by thiohydroximate toxicity. Analysis ofUGT74B1promoter activity during plant development reveals expression patterns consistent with glucosinolate metabolism and induction by auxin treatment. The results are discussed in the context of known mutations in glucosinolate pathway genes and their effects on auxin homeostasis. Taken together, our work provides complementaryin vitroandin vivoevidence for a primary role ofUGT74B1in glucosinolate biosynthesis. [ABSTRACT FROM AUTHOR]

The use of allyl protecting group mediated intramolecular aglycon delivery (IAD) as a strategy for intramolecular glycosylation has been extended to allow the stereoselective synthesis of α-glucofuranosides and β-rhamnopyranosides, in a totally stereoselective fashion. The efficiency of intramolecular glycosylation is dependent on the protecting group pattern of the glycosyl donor, and on the steric bulk of the glycosyl acceptor. [Copyright &y& Elsevier]

A new, almost odorless fluorous thiol is synthesized, which is utilized to prepare highly fluorinated thioglycosyl donors. These thioglycosides showed excellent reactivities in glycosylation reactions. The fluorous chain, stable under esterification, etherification, deacetylation, and glycosylation conditions, allowed facile purification of the thioglycosides by solid-phase extraction through fluorous silica gel. The fluorous thiol was readily recycled. [Copyright &y& Elsevier]