- MYRISTOYL ESTERS OF LACTOSE
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Whereas lactose did not undergo a base-catalyzed transesterification with methyl esters of fatty acids, methyl β-lactoside reacted under identical conditions to give mono- and di-myristates.This difference in behavior is explained in terms of the formatio
- Munavu, Raphael M,Nasseri-Noori, Bahman,Szmant, H. Harry
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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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- Conversion of β-glycopyranoside to α-glycopyranoside by photo-activated radical reaction
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By using carbon tetrachloride as the chloride radical and boron trifluoride etherate as the Lewis acid, the halogen-light-activated anomeric inversion of glycoside was achieved. This reaction is a novel guide to invert the glycosidic bond from a β-anomer to an α-anomer.
- Lai, Yu-Chen,Luo, Chin-Hung,Chou, Hsin-Chun,Yang, Cheng-Jhang,Lu, Le,Chen, Chien-Sheng
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supporting information
p. 2474 - 2477
(2016/05/24)
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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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- 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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- 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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- Synthesis and structure elucidation of benzoylated deoxyfluoropyranosides
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Benzoylated deoxyfluoropyranosides have been synthesized, starting with protected, unprotected, or fluorinated precursors. Fluorination of eight derivatives was compared using DAST and Deoxo-Fluor as reagents. Deoxo-Fluor was found to be especially useful
- Esmurziev, Aslan M.,Simic, Nebojsa,Hoff, Bard Helge,Sundby, Eirik
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scheme or table
p. 348 - 367
(2011/09/30)
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- Naucleamide F, a new monoterpene indole alkaloid from Nauclea Latifolia
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A new monoterpene indole alkaloid, naucleamide F (1), has been isolated from the bark and wood of Nauclea latifolia, and the structure and stereochemistry were elucidated on the basis of the spectral data. Naucleamide F (1) is a new monoterpene indole alk
- Kakuguchi, Yuka,Ishiyama, Haruaki,Kubota, Takaaki,Kobayashi, Jun'ichi
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experimental part
p. 765 - 771
(2009/12/01)
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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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- Samarium trifluoromethanesulfonate: An efficient moisture tolerant acylation catalyst under solvent-free condition
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Samarium trifluoromethanesulfonate catalyzed the acylation of phenols, alcohols, thiols, free reducing sugars, and glycosides in excellent yields at ambient temperature under solvent-free condition using stoichiometric amounts of various anhydrides. (Chemical Equation Presented). Copyright Taylor & Francis Group, LLC.
- Roy, Bimalendu,Dasgupta, Somnath,Kumar Rajput, Vishal,Mukhopadhyay, Balaram
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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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- 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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- Synthesis and nmr characterisation of methyl mono- and DI-0-α-L-rhamnopyranosyl-α-d-glucopyranosiduronic acids
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The synthesis and NMR characterisation of methyl mono- and di-O-α-L-rhamnopyranosyl-α-D-glucopyranosiduronic acids 1-6 are described. Two commercial starting products were used: methyl α-D-glucopyranoside 7 for the preparation of 1 and 2, and methyl (R)-4,6-O-benzylidene-α-D-glucopyranoside 8 for 3-6. Oxidation reaction of the hydroxymethyl group of glucose to a carboxylic acid group was performed by sodium hypochlorite 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-mediated procedure after the coupling reaction. Glycosylation was carried out using the trichloroacetimidate approach with trimethylsilyl trifluoromethanesulfonate (TMSOTf) as promoter, resulting in a completely stereoselective formation of the a glycosyl linkage.
- Battistelli, Chiara Laura,De Castro, Cristina,Iadonisi, Alfonso,Lanzetta, Rosa,Mangoni, Lorenzo,Parrilli, Michelangelo
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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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- Regioselective acylation of carbohydrates with 1-acyloxy-1H-benzotriazoles
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Acylation of representative carbohydrate derivatives was accomplished with in situ generated 1-acyloxy-1H-benzotriazoles. The observed high regioselectivity, mild reaction conditions and convenient work-up make the presented one-pot procedure generally applicable and more advantageous than acylations with previously introduced reagents, including N-acylimidazoles.
- Pelyvas,Lindhorst,Streicher,Thiem
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p. 1015 - 1018
(2007/10/02)
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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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- A Convenient Synthesis of 4-Thio-D-galactofuranose
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The synthesis of 4-thio-D-galactofuranose (15) and derivatives, starting from methyl α-D-glucopyranoside (1), is described.Esterification of 1 with N-benzoylimidazole afforded regioselectively methyl 2,3,6-tri-O-benzoyl-α-D-glucopyranoside (2c).Further su
- Varela, Oscar,Cicero, Daniel,Lederkremer, Rosa M. de
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p. 1884 - 1890
(2007/10/02)
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