- Carbon tetrachloride-free allylic halogenation-mediated glycosylations of allyl glycosides
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The allylic bromination of allyl glycosides is conducted using NBS/AIBN reagents in (EtO)2CO and PhCF3 solutions, without using CCl4 as a solvent. The activated mixed halo-allyl glycosides led to glycosylations, mediated by a triflate, in a latent-active
- Das, Anupama,Jayaraman, Narayanaswamy
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p. 9318 - 9325
(2021/11/13)
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- Direct dehydrative glycosylation catalyzed by diphenylammonium triflate
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Methods for direct dehydrative glycosylations of carbohydrate hemiacetals catalyzed by diphenylammonium triflate under microwave irradiation are described. Both armed and disarmed glycosyl-C1-hemiacetal donors were efficiently glycosylated in moderate to excellent yields without the need for any drying agents and stoichiometric additives. This method has been successfully applied to a solid-phase glycosylation.
- Hsu, Mei-Yuan,Lam, Sarah,Lin, Mei-Huei,Lin, Su-Ching,Wang, Cheng-Chung,Wu, Chia-Hui
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supporting information
(2020/03/13)
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- Chemical constituents of the aerial parts of Algerian Galium brunneum: Isolation of new hydroperoxy sterol glucosyl derivatives
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The liposoluble extract of Galium brunneum aerial parts from North-eastern Algeria was chemically investigated. The EtOAc soluble portion contained a series of glycosyl cucurbitacins and sterols including three new glucosyl hydroperoxy sterols 1–3 among other phenolic components whereas the BuOH soluble fraction was dominated by glycosyl derivatives of flavonoids, iridoids and lignans, according to the chemistry reported in the literature for the genus Galium. The structure of new oxidized sterols 1–3 was determined by spectroscopic methods as well as by comparison with related known metabolites. Selected main compounds from both extracts, which revealed moderate antibacterial activities, were tested for their growth inhibitory properties against Gram-positive and Gram-negative bacteria. This is the first report of cucurbitacins in plants of genus Galium.
- Bertella, Anis,Bitam, Fatma,Carbone, Marianna,Ciavatta, Maria Letizia,Gavagnin, Margherita,Smadi, Abla
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- Methyl 1,2-orthoesters as useful glycosyl donors in glycosylation reactions: A comparison with n-pent-4-enyl 1,2-orthoesters
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Mannopyranose-derived methyl 1,2-orthoacetates (R = Me) and -benzoates (R = Ph) can function as glycosyl donors - upon BF3·Et 2O activation in CH2Cl2 - in glycosylation reactions with monosaccharide acceptors to afford disaccharides in good yields. In the process, glycosylation is preferred to acid-catalyzed rearrangement leading to methyl mannopyranosides. Methyl 1,2-orthoesters can be also used in regioselective glycosylation protocols with monosaccharide diols, in which they display good regioselectivity. Copyright
- Uriel, Clara,Ventura, Juan,Gomez, Ana M.,Lopez, J. Cristobal,Fraser-Reid, Bert
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experimental part
p. 3122 - 3131
(2012/07/13)
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- Blurring the boundary between bio- and geohopanoids: Plakohopanoid, a C32 biohopanoid ester from Plakortis cf. lita
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Plakohopanoid (3a), a new type of hopanoid derivative composed of a C 32 hopanoid acid ester linked to a mannosyl-myo-inositol, was isolated from the sponge Plakortis cf. lita as its peracetyl derivative 3b. The structure of 3b was determined by a combination of spectroscopic analysis and micro-scale chemical degradation. Even though plakohopanoid was isolated from a sponge, its component parts are clearly of bacterial origin, and its bacterial biosynthesis is very likely. Until now, C32 hopanoic acids have been considered to be geohopanoids, i.e., diagenetic products that are formed through abiotic degradation of the biohopanoids present in bacteria. The presence of 3a in a marine living organism shows that there is a biosynthetic pathway to C32 hopanoic acids, and these substances should therefore no longer with certainty be considered to be geohopanoids. Copyright
- Costantino, Valeria,Sala, Gerardo Della,Mangoni, Alfonso,Perinu, Cristina,Teta, Roberta
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p. 5171 - 5176
(2012/10/29)
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- Unexpected stereocontrolled access to 1α,1′β-disaccharides from methyl 1,2-ortho esters
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Mannopyranose-derived methyl 1,2-orthoacetates (R = Me) and 1,2-orthobenzoates (R = Ph) undergo stereoselective formation of 1α,1′β-disaccharides, upon treatment with BF 3?Et2O in CH2Cl2, rather than the expected acid-catalyzed reaction leading to methyl glycosides by way of a rearrangement-glycosylation process of the liberated methanol.
- Uriel, Clara,Ventura, Juan,Gomez, Ana M.,Lopez, J. Cristobal,Fraser-Reid, Bert
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experimental part
p. 795 - 800
(2012/03/22)
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- Neurosporaside, a tetraglycosylated sphingolipid from neurospora crassa
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The new tetraglycosylceramide neurosporaside (1a) has been isolated from the fungus Neurospora crassa. Neurosporaside is a tetraglycosylated glycosphingolipid characterized by a sugar chain unprecedented among natural glycoconjugates. The structure of neurosporaside was elucidated by extensive spectroscopic analysis and microscale degradation analysis, which allowed full structure elucidation using less than 1 mg of compound.
- Costantino, Valeria,Mangoni, Alfonso,Teta, Roberta,Kra-Oz, Galia,Yarden, Oded
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experimental part
p. 554 - 558
(2011/06/24)
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- Indium(III) triflate-mediated one-step preparation of glycosyl halides from free sugars
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In(OTf)3 has been found to be an efficient catalyst for the direct conversion of reducing sugars to their respective acylated glycosyl halides in good yields under mild conditions. The glycosyl halides so obtained can be converted to alkyl glyc
- Giri, Santosh Kumar,Kartha, K. P. Ravindranathan
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scheme or table
p. 3378 - 3383
(2010/12/25)
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- Amphiceramide A and B, novel glycosphingolipids from the marine sponge Amphimedon compressed
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Glycolipid analysis of the Caribbean sponge Amphimedon compressa has shown it to contain two novel glycosphingoli- pids, amphiceramide A (1a) andB(2a), which possess an unusual A6-phytosphingosine. The saccharide chain of amphiceramide A is composed of a
- Costantino, Valeria,Fattorusso, Ernesto,Imperatore, Concetta,Mangoni, Alfonso,Teta, Roberta
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experimental part
p. 2112 - 2119
(2009/09/06)
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- 1 Hand 13C NMR data of methyl tetra-O-benzoyl-D- pyranosides in acetone-d6
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Complete assignments of 1H- and 13C-NMR resonances of five methyl tetra-O-benzoyl-D-pyranosides based on 1H, 13C, 2D DQF-COSY, HMQC, HMBC and HSQC-TOCSY experiments have been performed. Copyright
- Esmurziev, Asian,Simic, Nebojsa,Sundby, Eirik,Hoff, Bard Helge
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experimental part
p. 449 - 452
(2010/04/30)
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- Regioselective C-6 hydrolysis of methyl O-benzoyl-pyranosides catalysed by candida rugosa lipase
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Hydrolysis of six methyl O-benzoyl-pyranosides has been investigated using Candida rugosa lipase in dioxane/buffer mixtures. The lipase catalysed the hydrolysis of all substrates in a regiospecific manner at C-6, The rate of reaction was dependent on pyra
- Esmurziev, Asian,Sundby, Eirik,Hoff, Bard Helge
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body text
p. 1592 - 1597
(2009/09/08)
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- Structure and absolute stereochemistry of syphonoside, a unique macrocyclic glycoterpenoid from marine organisms
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(Figure Presented) The glycoterpenoid syphonoside (1) is the main secondary metabolite of both the marine mollusk Syphonota geographica and the sea-grass Halophila stipulacea, two Indo-Pacific species migrated to the Mediterranean Sea through the Suez Canal. The structure and the absolute stereochemistry of 1, which displays unique structural features, has been accomplished by using a combination of spectroscopic techniques, degradation reactions, and conformational analysis methods. Compound 1 was able to inhibit high density induced apoptosis in a number of human and murine carcinoma cell lines.
- Gavagnin, Margherita,Carbone, Marianna,Amodeo, Pietro,Mollo, Ernesto,Vitale, Rosa Maria,Roussis, Vassilios,Cimino, Guido
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p. 5625 - 5630
(2008/02/09)
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- Iodine promoted glycosylation with glycosyl iodides: α-glycoside synthesis
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Glycosidation of fully acetylated glucopyranosyl iodide with methanol under the influence of iodine gave α-glucoside selectively. Use of less reactive acceptors led to the formation of α/β-mixtures. Glycosylations with fully benzoylated glucosyl iodide yielded β-glucosides only. In contrast, iodine-promoted glycosylation of serine and threonine with 2-azido-2-deoxy-glycosyl iodides, easily obtained in three steps, proceeded smoothly, resulting in only α-linked products in high yield in most cases. Copyright Taylor & Francis, Inc.
- Van Well, Renate M.,Kartha, K. P. Ravindranathan,Field, Robert A.
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p. 463 - 474
(2007/10/03)
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- Glycolipids from sponges. Part 16.1 discoside, a rare myo-Inositol-containing glycolipid from the caribbean sponge Discodermia dissoluta
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Discoside (1a), a glycolipid composed of 4,6-O-diacylated mannose attached to the 2-hydroxyl group of a myo-inositol unit, was isolated as a mixture of homologues from the marine sponge Discodermia dissoluta. The complete stereostructure of this new glycolipid was solved by interpretation of mass spectrometric and NMR data and CD analysis of degradation products.
- Barbieri, Lucia,Costantino, Valeria,Fattorusso, Ernesto,Mangoni, Alfonso
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p. 1527 - 1530
(2008/09/20)
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- Combinatorial synthesis of an oligosaccharide library by using β-bromoglycoside-mediated iterative glycosylation of selenoglycosides: Rapid expansion of molecular diversity with simple building blocks
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A new method for constructing an oligosaccharide library composed of structurally defined oligosaccharides is presented based on an iterative glycosylation of selenoglycosides. Treatment of 2-acyl-protected selenoglycosides with bromine selectively generates β-bromoglycosides, which serve as glycosyl cation equivalents in the oligosaccharide synthesis. Thus, the coupling of the bromoglycosides with another selenoglycoside affords the corresponding glycosylated selenoglycosides, which can be directly used to next glycosylation. The iteration of this sequence allows the synthesis of a variety of oligosaccharides including an elicitor active heptasaccharide. A characteristic feature of the iterative glycosylation is that glycosyl donors and acceptors with the same anomeric reactivity can be selectively coupled by activation of the glycosyl donor prior to coupling with the glycosyl acceptor. Therefore, same selenoglycosides can be used for both the glycosyl donors and the acceptors. This feature has been exemplified by a construction of an oligosaccharide library directed to elicitor-active oligosaccharides. The library composed of stereochemically defined oligoglucosides with considerable structural diversity can be constructed starting from simple selenoglycosides.
- Yamago, Shigeru,Yamada, Takeshi,Ito, Hiroki,Hara, Osamu,Mino, Yosuke,Yoshida, Jun-Ichi
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p. 6159 - 6174
(2007/10/03)
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- Vesparioside from the marine sponge Spheciospongia vesparia, the first diglycosylceramide with a pentose sugar residue
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The marine sponge Spheciospongia vesparia produces vesparioside (1a), a diglycosylated glycosphingolipid which is the first example of a natural diglycosylceramide with a pentose sugar residue. The structure of vesparioside was mostly determined by extensive spectroscopic analysis but determination of the nature of the alkyl chains and elucidation of the absolute stereochemistry of the sugars and of the ceramide required chemical degradation. In this respect, an improved and simplified procedure for the microscale chemical degradation of glycosphingolipids was employed here for the first time. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Costantino, Valeria,Fattorusso, Ernesto,Imperatore, Concetta,Mangoni, Alfonso
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p. 368 - 373
(2007/10/03)
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- A new method for the synthesis of stannyl ethers by acid-catalyzed reaction of alcohols with allyltributylstannane
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Stannyl ethers are prepared by triflic acid-catalyzed reaction of alcohols with tributylstannane or allyltributylstannane at room temperature. The stannyl ethers thus prepared can be successfully used for the β-bromogycoside-mediated glycosylation reactions.
- Yamago, Shigeru,Yamada, Takeshi,Nishimura, Ryuji,Ito, Hiroki,Mino, Yosuke,Yoshida, Jun-Ichi
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p. 152 - 153
(2007/10/03)
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- A new, iterative strategy of oligosaccharide synthesis based on highly reactive β-bromoglycosides derived from selenoglycosides
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equation presented Stereoselective conversion of a selenoglycoside to a β-bromoglycoside in the absence of a glycosyl acceptor followed by the coupling with another selenoglycoside affords the corresponding glycosylated selenoglycoside, which could be dir
- Yamago, Shigeru,Yamada, Takeshi,Hara, Osamu,Ito, Hiroki,Mino, Yosuke,Yoshida, Jun-Ichi
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p. 3867 - 3870
(2007/10/03)
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- Programmable one-pot oligosaccharide synthesis
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In an effort to develop a broadly applicable approach to the facile one- pot synthesis of oligosaccharides, the reactivity of a number of p- methylphenyl thioglycoside (STol) donors which are either fully protected or have one hydroxyl group exposed has b
- Zhang, Zhiyuan,Ollmann, Ian R.,Ye, Xin-Shan,Wischnat, Ralf,Baasov, Timor,Wong, Chi-Huey
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p. 734 - 753
(2007/10/03)
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- Reductive cleavage of the positional isomers of benzoylated and methylated methyl α-D-mannopyranoside
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The four O-benzoy-tri-O-methyl positional isomers, the six di-O-benzoyl-di-O-methyl positional isomers, the four tri-O-benzoyl-O-methyl positional isomers, and the tetra-O-benzoyl derivative of methyl α-D-mannopyranoside were synthesized, characterized, a
- Rozanas, Christine R.,Gray, Gary R.
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p. 243 - 249
(2007/10/03)
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- THIOGLYCOSIDES AS POTENTIAL GLYCOSYL DONORS IN ELECTROCHEMICAL GLYCOSYLATION REACTIONS. PART 1: THEIR PREPARATION AND REACTIVITY TOWARD SIMPLE ALCOHOLS
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Costant potential electrolysis of several glycosyl donors such as substituted phenyl 2,3,4,6-tetra-O-acetyl, benzoyl or benzyl-1-thio-β-D-gluco or galactopyranosides in dry acetonitrile in the presence of various primary, secondary or tertiary alcohols performed in an undivided cell, gave preferentially β-linked saccharides in moderate to good yields according to the nature of the protective groups on the sugar moiety. 2-Deoxy-2-phthalimido-1-thio-β-D-gluco derivatives gave the β-glucosides selectively in excellent yields.It was found, as expected, that substitution of the phenyl group with methoxy or methyl radicals facilitates the electrochemical glycosylation reaction by lowering the oxidation potentials of the corresponding thioglycosides.
- Balovoine, Gilbert,Berteina, Sabine,Gref, Aurore,Fischer, Jean-Claude,Lubineau, Andre
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p. 1217 - 1236
(2007/10/03)
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- Lithium aluminium hydride reduction of glycopyranoside-monosulfonates: Formation of branched furanosides
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Lithium aluminum hydride reduction of glycopyranoside-monotosylates caused three reactions: (1) stereospecific 1,2-shift, producing branched furanosides (path A), (2) reductive O-S bond cleavage, producing the original glycosides (path B), and (3) reductive removal of the tosyloxy group, producing deoxyglycosides (path C). The path A reaction was particularly evident for the monotosylates at 2-O, 3-O, and 4-O: for example, methyl 2-O-tosyl-α-D-xylopyranoside gave methyl 2-deoxy-2-C-(hydroxymethyl)-α-D-α-erythrofuranoside in 60% yield. This reaction opens a new and efficient route to branched glycofuranosides of natural and unnatural type. Stereo-electronic requirements of this reaction in relation to the balance of the other two reactions are discussed.
- Tsuda,Nishimura,Ito
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p. 1983 - 1989
(2007/10/02)
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- NOVEL D-GLUCANS OBTAINED BY DIMETHYL SULFOXIDE EXTRACTION OF THE LICHENS Letharia vulpina, Actinogyra muehlenbergii, AND AN Usnea SP.
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Extraction of certain lichens with cold dimethyl sulfoxide provided a β-D-glucan virtually free of contaminating α-D-glucan and galactomannan.Applied to Letharia vulpina, the method gave β-D-glucan, and extraction of the residue with hot water followed by cooling gave α-D-glucan.From Usnea sp. a β-D-glucan was isolated, but little α-D-glucan was present.Extraction of Actinogyra muehlenbergii provided a (16)-linked β-D-glucopyranan containing one acetyl group of every 8-9 glucosyl units, being present almost exclusively as monosubstituent at O-2, O-3, and O-4.
- Iacomini, Marcello,Gorin, Philip A. J.,Baron, Madalena,Tulloch, Alexander P.,Mazurek, Mytosk
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p. 117 - 126
(2007/10/02)
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