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Synthetic analogues of the naturally occurring iminosugar homoDMDP, which feature a perfluoroalkyl group at the pseudo-anomeric position, have been synthesized from the corresponding sugar-derived cyclic aldonitrone. The new fluorinated iminosugars as well as homoDMDP and its 6-deoxy counterpart were evaluated for their inhibitory activity against a panel of glycosidases. While the replacement of the (1′,2′)-dihydroxyethyl substituent of homoDMDP with –C 4 F 9 proved detrimental for enzyme binding, introduction of a –C 3 F 7 moiety tuned the inhibitory activity spectrum selectively towards α-fucosidase and α-glucosidase from yeast. [ABSTRACT FROM AUTHOR]

Abstract: Domino reactions involving metal–halogen exchange, furanose ring-opening and nucleophilic addition from 3-O-benzyl-5-deoxy-5-iodo-1,2-O-isopropylidene-α-d-xylofuranose and the epimeric l-arabino derivative with various organometallic reagents are reported. In anhydrous conditions, with a large excess of organolithium or Grignard reagents, vicinal diols are obtained with good yields and a fair diastereoselectivity. Interestingly, with α-trimethylsilyl organolithium reagents, the fragmentation of the furanose ring to the substituted pent-4-enal is followed by a Peterson olefination giving dienic compounds in a four-step one-pot process. [Copyright &y& Elsevier]

Abstract: The transformation of d-xylose and l-arabinose, the two major components of wheat straw and bran, into a unique multifunctional, optically pure, five-carbon synthon has been achieved. The synthetic sequence requires three steps: suitable protection of the hydroxyl groups of the pentoses, introduction of an iodide at the C-5 position and zinc-mediated opening of the furanose ring leading to the formation of a common substituted pent-4-enal. [Copyright &y& Elsevier]

Abstract: The title compounds are prepared by cycloaddition of perfluoroalkenyl ketones and 1,3-dienes, with a subsequent aromatization by basic dehydrofluorination. The perfluoroalkenyl ketones were prepared by the reaction of perfluoroorganometallic reagents with acylsilanes. The transformation may be performed more efficiently in a simplified process without purification of the intermediate cycloadducts. The overall methodology is an interesting entry to ortho-perfluoroalkyl phenones with the possibility to vary the substitution at the acyl and on the ring moiety. [Copyright &y& Elsevier]

Abstract: Galactofuranose is a widespread component of cell wall polysaccharides in bacteria, protozoa and fungi, but is totally absent in mammals. Importantly, galactofuranose is a key constituent of major cell envelope polysaccharides in pathogenic mycobacteria. In this respect, galactofuranose-based glycoconjugates are interesting target molecules for drug design. O-Glycosidases and notably β-d-galactofuranosidases could be useful tools for the chemoenzymatic synthesis of galactofuranosides, but to date no studies of this type have been reported. Here we report the use of a GH 51 α-l-arabinofuranosidase for the synthesis of β-d-galactofuranosides. We have demonstrated that this enzyme can catalyse both the autocondensation of p-nitrophenyl-β-d-galactofuranoside and the transgalactofuranosylation of benzyl α-d-xylopyranoside, forming p-nitrophenyl β-d-galactofuranosyl-(1→2)-β-d-galactofuranoside and benzyl β-d-galactofuranosyl-(1→2)-α-d-xylopyranoside, respectively. Both reactions were very regiospecific and the reaction involving benzyl α-d-xylopyranoside afforded very high yields (74.8%) of the major product. To our knowledge, this demonstration of chemoenzymatic synthesis of galactofuranosides constitutes the very first use of an O-glycosidase for the synthesis of galactofuranosides. [Copyright &y& Elsevier]

To date, the enzymatically-catalysed synthesis of pentose-containing compounds has been limited to the production of oligo-β-(1 → 3) and oligo-β-(1 → 4)-linked xylopyranosides. To our knowledge, no such syntheses have involved arabinofuranose or, indeed, any other sugars in the furanose configuration. In this report, we describe the use of a thermostable α-l-arabinofuranosidase for the synthesis of p-nitrophenyl α-l-arabinofuranosyl-(1 → 2)-α-l-arabinofuranoside, p-nitrophenyl β-d-xylopyranosyl-(1 → 2)-β-d-xylopyranoside, p-nitrophenyl β-d-xylopyranosyl-(1 → 3)-β-d-xylopyranoside and benzyl α-d-xylopyranosyl-(1 → 2)-α-l-arabinofuranoside. Importantly, this latter compound is synthesised in a highly regiospecific reaction, which leads to the production of a single disaccharide. [Copyright &y& Elsevier]

The preparation of aliphatic, aromatic or functionalized tartramides directly from tartaric acid and amines under microwaves activation is described. A preliminary study of the chelating properties of some functionalized tartramides towards Cu2+ ions is reported. To cite this article: R. Plantier-Royon, C. R. Chimie 7 (2004). [Copyright &y& Elsevier]

Water‐soluble and air‐stable gold nanoparticles stabilized by a xyloside‐based ligand containing a pyridine ring‐functionalized 1,2,3‐triazole backbone were prepared in the presence of a reducing agent. During their preparation, UV‐vis and NMR spectroscopic techniques were used to study the interaction between the xyloside ligand and Au(III) ions. These AuNPs were characterized by UV‐vis spectroscopy, TEM and DLS and showed a small size (average diameter<10 nm determined by TEM). Their catalytic activity was tested in the reduction of 4‐nitrophenol (4‐NP) to 4‐aminophenol (4‐AP) in water. [ABSTRACT FROM AUTHOR]

A short and convenient approach to the original xyloside‐based ligands, has been achieved, using d‐xylose as a starting material. The complexation properties of these ligands towards Au(III) cations were studied by different methods, such as multinuclear NMR, mass spectrometry, elemental analysis. A preliminary study using protometric titrations has been carried out in aqueous solution under various pH conditions, thus in order to investigate the binding of Au(III) cations to these ligands. Furthermore, molecular calculations were performed to obtain additional structural information. The catalytic activity of the most stable Au(III) complexes was evaluated for the homogeneous reduction of 4‐nitrophenol (4‐NP) to 4‐aminophenol (4‐AP) in the presence of NaBH4. [ABSTRACT FROM AUTHOR]

An unprecedented reactivity of CF3-TMS has been revealed, which exploits the basic character of the generated [CF3-] capable of delivering dichloromethide from dichloromethane with subsequent transfer to nitrones under smooth conditions. The proton-abstraction pathway was demonstrated through isotopic labeling experiments in CD2Cl2. The same reaction was achieved in acetonitrile with the introduction of a cyanomethyl group onto the nitrones. [ABSTRACT FROM AUTHOR]

Abstract: A series of highly fluorinated compounds bearing two or four perfluoroalkyl (R F ) chains, with a flexible or rigid core have been synthesized. Radical additions, nucleophilic addition or condensation reactions were implemented for these synthesis, using perfluoroalkylated iodides and alcohols and various type of substrates: bis(allylic) derivatives, epichlorhydrin, diacid derivatives. All compounds contain an unsaturated moiety (vinyl, allyl or internal double bond) to be grafted on silicone materials by a catalyzed hydrosilylation reaction. [Copyright &y& Elsevier]

Direct and efficient preparation of pentyl and octyl β-d-xylosides and oligoxylosides has been achieved from xylans and n-pentanol or n-octanol in aqueous medium with xylanases. The method has been successfully applied with xylooligosaccharides produced from hydrothermally pretreated wheat bran to produce octyl oligoxylosides. The pentose-based surfactants thus obtained exhibit good surface properties compared to other alkyl glycosides. These molecules represent interesting candidates for the production of new green surfactants. [ABSTRACT FROM AUTHOR]

Direct and efficient preparation of pentyl and octyl β-d-xylosides and oligoxylosides has been achieved from xylans and n-pentanol or n-octanol in aqueous medium with xylanases. The method has been successfully applied with xylooligosaccharides produced from hydrothermally pretreated wheat bran to produce octyl oligoxylosides. The pentose-based surfactants thus obtained exhibit good surface properties compared to other alkyl glycosides. These molecules represent interesting candidates for the production of new green surfactants. [ABSTRACT FROM AUTHOR]

In the framework of a project devoted to the chemical transformation of monosaccharides from hemicelluloses into higher added value materials, the zinc-induced reductive elimination from 5-deoxy-5-iodo derivatives of D-xylose and L-arabinose was carried out. This study gave us the opportunity to observe surprising behaviors. In particular, the reaction strongly depends on structural parameters (protecting group pattern, configuration at C-4) and on the presence of Zn2+ ions. Collaterally with the experimental work, water solvent PCM HF-DVF (MPW I KILANL2DZ) computations were performed to obtain insight into the mechanism for the reductive part of the reaction sequence. Without Zn2+, the zinc insertion reaction was found to proceed through a concerted but non-synchronous process involving a relatively large energy barrier (32 kcal mol-1) that directly leads to the presumed organozinc intermediate. In the presence of Zn2+, a three-step mechanism was identified in which the cation coordinates the anomeric and ring oxygen atoms and also the sugar iodine atom, causing an activating effect on the zinc insertion process by facilitating the homolytic rupture of the C-I bond. Complexes between zinc and Zn2+ bound carbohydrates were characterized with large stabilization energies, suggesting that Zn2+ might enhance the affinity of the organic compound with the zinc metal surface. [ABSTRACT FROM AUTHOR]

Perfluoroalkenyl ketones, obtained by reaction of perfluoroorganometallic reagents with acylsilanes, are shown to be versatile dienophiles in Diels–Alder reactions with various dienes. [Copyright &y& Elsevier]

A novel strategy for the synthesis of 2‐substituted thioglycals has been developed from a carbohydrate‐derived ketene dithioacetal in a two‐step sequence. The introduction of various electrophilic groups at the double bond of the ketene dithioacetal was achieved before the elimination of the thioalkyl group to yield 2‐substituted thioglycals. Removal of the exocyclic thioalkyl group was obtained by the selective formation of the exocyclic glycosyl sulfoxide followed by treatment by an organolithium reagent. The synthetic potential of these 2‐substituted thioglycals was illustrated by the alkylation at the sulfur atom leading to unsaturated carbohydrate‐derived sulfonium salts. [ABSTRACT FROM AUTHOR]

Front Cover: A Xyloside-Based Ligand to Stabilize Gold Nanoparticles: Preparation and Application (Eur. J. Inorg. Gold, nanoparticles, nitrophenol, triazole, xylose Keywords: Gold; nanoparticles; nitrophenol; triazole; xylose EN Gold nanoparticles nitrophenol triazole xylose 1 1 1 06/27/23 20230623 NES 230623 B The Front Cover b shows a gold nanoparticle decorated with a simple xyloside ligand having a 1,2,3-triazole backbone functionalized with a pyridine ring. [Extracted from the article]

Efficient enzymatic synthesis of d -xylose and l -arabinose lauryl mono- and diesters has been achieved by transesterification reactions catalysed by immobilized Candida antarctica lipase B as biocatalyst, in organic medium in the presence of d -xylose or l -arabinose and vinyllaurate at 50 °C. In case of l -arabinose, one monoester and one diester were obtained in a 57% overall yield. A more complex mixture was produced for d -xylose as two monoesters and two diesters were synthesized in a 74.9% global yield. The structures of all these pentose laurate esters was solved. Results demonstrated that the esterification first occurred regioselectively onto the primary hydroxyl groups. Pentose laurate esters exhibited interesting features such as low critical aggregation concentrations values all inferior to 25 μM. Our study demonstrates that the enzymatic production of l -arabinose and d -xylose-based esters represents an interesting approach for the production of green surfactants from lignocellulosic biomass-derived pentoses. [ABSTRACT FROM AUTHOR]

Different mono-xylosides and their corresponding xylobiosides obtained by a chemo-enzymatic approach featuring various substituents attached to a triazole ring were probed as priming agents for glycosaminoglycan ( GAG) biosynthesis in the xylosyltransferase-deficient pgsA-745 Chinese hamster ovary cell line. Xylosides containing a hydrophobic aglycone moiety were the most efficient priming agents. Mono-xylosides induced higher GAG biosynthesis in comparison with their corresponding xylobiosides. The influence of the degree of polymerization of the carbohydrate part on the priming activity was investigated through different experiments. We demonstrated that in case of mono-xylosides, the cellular uptake as well as the affinity and the catalytic efficiency of β-1,4-galactosyltransferase 7 were higher than for xylobiosides. Altogether, these results indicate that hydrophobicity of the aglycone and degree of polymerization of glycone moiety were critical factors for an optimal priming activity for GAG biosynthesis. [ABSTRACT FROM AUTHOR]

The extraction of pesticides from aqueous solutions using new ionic liquids (ILs) derived from glycine betaine as extractants was investigated. These ILs incorporate cationic esters of trimethyl(2-alkoxy-2-oxoethyl) ammonium (GBOC n + ) associated with inorganic ClO 4 − or BF 4 − anions. First, batch extraction experiments were performed by using the liquid–liquid biphasic system IL/ethyl acetate/water (1:1:1; v/v) for four commonly used pesticides: 4-chlorophenoxyacetic acid (4-CPA), 2,4-dichlorophenoxyacetic acid (2,4-D), 2-[(4-methyl-5-oxo-3-propoxy-1,2,4-triazolin-1-yl)carbamidosulfonyl]benzoic acid methyl ester sodium salt (propoxycarbazone) and 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-5-methoxymethyl nicotinic acid (imazamox). Then, the liquid–liquid extraction unit operation was intensified by transposing the system into a Centrifugal Partition Extraction (CPE) device, using ethyl acetate/ n -butanol/water (1:4:5; v/v) as biphasic solvent system and potassium iodide, sodium iodide or sodium perchlorate as potential displacers. The use of a lab-scale CPE column with a capacity of 300 mL allowed the intensification of the extraction procedure. The extraction and back-extraction of individual or mixture of pesticides were studied, with a particular focus on the potential separation of individual pesticides and on the recyclability of the CPE method. In optimal CPE conditions, a quantitative extraction for three of the four pesticides was obtained, with recovery percentages of 95.6%, 98.7%, 99.0%, and 100.0% for imazamox, propoxycarbazone, 2,4-D, and 4-CPA, respectively. After the back-extraction step, separated pesticides were recovered in fresh aqueous mobile phase. The recyclability studies showed that the extraction/back-extraction process can be performed at least four times while maintaining a quantitative extraction. [ABSTRACT FROM AUTHOR]

A series of new “green” ionic liquids was prepared in two or three steps from natural and low expense Glycine Betaine (GB). Esterification of GB was carried out with methanesulfonic acid and primary alcohols with alkyl chains containing 6, 12, 14, 16 and 22 atoms of carbon. Anionic metathesis from these cationic esters with inorganic (ClO 4 − , BF 4 − ) or biobased (( S )-CH 3 -CHOH-COO − (Lac − )) anions was then achieved to afford a range of fully characterized ionic liquids. The influence of the alkyl chain length and the chemical nature of the counter anion on physicochemical properties such as melting point, glass transition, decomposition temperatures and viscosity has been investigated. [ABSTRACT FROM AUTHOR]

Fucosidase inhibitors represent captivating targets for various biological applications. Iminosugars featuring a fluoroalkyl chain in the pseudoanomeric position were synthesized by nucleophilic addition of a perfluoroalkyl Grignard reagent to a nitrone. Reduction of the N-O bond of the hydroxylamine was achieved by treatment with an aqueous solution of sulfur dioxide. The p Ka = 4.5 of the target pyrrolidine reflected a strong electronic effect of the fluoroalkyl chain. Inhibitory potencies of the fluorinated iminosugars and their corresponding hydroxylamines were evaluated against α- L-fucosidase at various pH values. [ABSTRACT FROM AUTHOR]

A series of diastereomeric tetrahydroxylated azepanes featuring a carboxymethyl group at the pseudo-anomeric position have been synthesized from a common unsaturated intermediate. Syn - and anti -dihydroxylation reactions were achieved to yield the target compounds after efficient one-step deprotection of carbamate, ester and acetonide groups simultaneously. Screening of these polyhydroxylated azepanes toward a range of commercially available glycosidases was performed and one of the stereoisomers showed potent and selective inhibition toward β-galactosidase (IC 50 = 21 μM). [ABSTRACT FROM AUTHOR]

The dichloromethylation and cyanomethylation of nitrones in the presence of the strong base [CF3-] is described. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mutations of aromatic residues in the aglycone binding subsite of a β-xylosidase modify its hydrolytic and transglycosylation activities. [•] F116, F167 and Y284 play an important role in hydrolysis of pNP β-d-Xylp. [•] F116 represents an interesting target to enhance the transglycosylation reaction with octanol. [ABSTRACT FROM AUTHOR]

Abstract: A convenient approach to the construction of dihydroxylated unsaturated azepanes featuring a functional group (ethoxycarbonyl)methyl or (cyano)methyl at C-2 was achieved from a pent-4-enal synthon obtained in four steps from d-xylose. The key step of the sequence relied on the conjugate addition of allylamine to α,β-unsaturated ester or nitrile, prepared by Wadsworth–Emmons olefination. Subsequent RCM afforded the target unsaturated azepanes. [Copyright &y& Elsevier]

The synthesis of new class of potential TPase inhibitorscontaining a difluoromethylphosphonate function as phosphate mimicis reported. This new series was prepared from a readily availablefluorinated building block in few steps. Two series were evaluatedas potential inhibitors: a linear series and a conformational constrainedseries. The activity of these multisubstrate inhibitors depends onthe size of the spacer introduced between the pyrimidine ring andthe phosphonate function. Best results were observed from triazolylderivatives, easily obtained from propargylthymine and correspondingazides. [ABSTRACT FROM AUTHOR]

Abstract: The interactions of three amphiphilic glycoligands derived from d-galacturonic acid (L1, L2 and L3) with copper (II) ions were investigated in aqueous solution and/or in aqueous-methanol media. The combination of potentiometry, UV–Vis spectrophotometry and Electron Paramagnetic Resonance (EPR) was used to determine the formation constants of the complexes and their relative structures in solution. The complexation sites were identified using electronic absorption and EPR spectroscopies. Copper complexes were obtained as square planar or square pyramidal mononuclear or dinuclear species. Solid compounds were synthesized and tested as catalysts in the autooxidation of catechols in methanol and in aqueous micellar media. Mononuclear species were found to be catalytically active in both media, whereas dinuclear ones do not show any significant catecholase activity. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a convenient and efficient synthesis of new complexing surfactants from d-galacturonic acid and n-octanol as renewable raw materials in a two-step sequence. In the first step, simultaneous O-glycosidation–esterification under Fischer conditions was achieved. The anomeric ratio of the products was studied based on the main experimental parameters and the activation mode (thermal or microwave). In the second step, aminolysis of the n-octyl ester was achieved with various functionalized primary amines under standard thermal or microwave activation. The physico-chemical properties of these new amphiphilic ligands were measured and these compounds were found to exhibit interesting surface properties. Complexing abilities of one uronamide ligand functionalized with a pyridine moiety toward Cu(II) ions was investigated in solution by EPR titrations. A solid compound was also synthesized and characterized, its relative structure was deduced from spectroscopic data. [Copyright &y& Elsevier]

Abstract: Nitrogen-in-the-ring analogues of l-fucose and l-rhamnose were prepared, which feature a spirocyclopropyl moiety in place of the methyl group of the natural sugar. The synthetic route involved a titanium-mediated aminocyclopropanation of a glycononitrile as the key step. Four new spirocyclopropyl iminosugar analogues were generated, which displayed some activity towards l-fucosidase and l-rhamnosidase. [Copyright &y& Elsevier]

Abstract: A series of sulfonium salts derived from 1,5-dithiopent-1-enopyranosides was prepared in a three-step sequence from protected d- and l-erythrofuranoses. The key step is the nucleophilic displacement of a leaving group by a sulfur atom of carbohydrate-derived ketene dithioacetals. Such compounds were assayed for their properties as glycosidase inhibitors. [Copyright &y& Elsevier]

Abstract: The synthesis of a fully deprotected ketimine-type iminosugar is reported, starting from commercial d-mannose diacetonide. An appropriate solvent system was critical for the success of the key tandem addition/cyclization reaction. Reduction of the imine was also achieved to yield the corresponding pyrrolidine in a stereoselective manner. The cyclic sugar imine displayed modest fucosidase inhibitory activity when compared to the saturated analogue. [Copyright &y& Elsevier]

The biological activity of unsaturated iminosugars has not yet been extensively studied because of a lack of general synthetic methods. A practical synthesis of these cyclic ketimine sugars was developed, which was based on a tandem addition-cyclization reaction of a Grignard reagent to a ω-methanesulfonylglycononitrile. [ABSTRACT FROM AUTHOR]

A highly diastereoselective nucleophilic mono(trifluoromethylation) of a tartaric acid-based diketone, using trifluoromethyl(trimethyl)silane, afforded the corresponding γ-keto trifluoromethylcarbinol. The scope and limitation of this reaction was studied. The acidic removal of the acetonide moiety protecting the two hydroxyl groups of the adducts was unsuccessful. Bis(O-methylation) of the aromatic derivatives under basic conditions, followed by acidic hydrolysis and oxidative cleavage, led to two different enantiopure products: an α-aryl-α-methoxy-α-trifluoromethyl ethanal and an α-aryl-α-methoxycarboxylic acid. The overall process is eventually an interesting way to convert one natural chiral raw material into two functionalized enantiopure building blocks including a trifluoromethyl one. [ABSTRACT FROM AUTHOR]

Abstract: Polyhydroxy 4-azaspiro[2.4]heptane derivatives (spirocyclopropyl iminosugars) were prepared in four to six steps from readily available protected aldoses. The key step of the reaction sequence involves a titanium-mediated aminocyclopropanation of glycononitriles with subsequent cyclization. Five new polyhydroxypyrrolidines so-obtained have been evaluated for their ability to inhibit 16 glycosidases. One of them exhibits selective inhibition of α-l-fucosidase from bovine kidney (K i =1.6μM, competitive). [Copyright &y& Elsevier]

Abstract: The interactions of three bis(amide) ligands derived from tartaric acid with copper (II) were investigated in aqueous solution by a combination of potentiometry, UV–vis spectrophotometry, electron paramagnetic resonance (EPR), and mass spectrometry. The formation constants of the complexes were measured and their relative structures were reported. The sites of complexation of these ligands are investigated based mostly on their electronic and EPR spectra and on the comparison with the behaviour of some analog compounds. [Copyright &y& Elsevier]

A thermostable α-l-arabinofuranosidase was tested for its ability to perform transglycosylation with different alcohol acceptors. Reactions were characterized by high rates with optimal synthesis being obtained within 10 min. Both primary and secondary alcohols could act as acceptors in transarabinosylation but yields of alkyl arabinosides decreased with increasing alkyl chain length. [Copyright &y& Elsevier]

Review: 260 refs. [ABSTRACT FROM AUTHOR]

A diagram is presented which explains the chemical process of Perfluoroalkylation of Nitrones for the Synthesis of a Series of Fucosidase Inhibitors.

Key steps in the synthesis of azepanes (VIII) and (X), which are of interest as glycosidase inhibitors, are the conjugate addition of allylamine to the precursor (III) and final ring-closing metathesis with the pure diastereomers (VII) and (IX). [ABSTRACT FROM AUTHOR]