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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]

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]

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]

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]

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]

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]

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]

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]