- Halogenation and anomerization of glycopyranoside by TESH/bromine and BHQ/bromine
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Treatment of peracetylated glycosides and β-isopropyl glycosides with halogen in the presence of TESH and BHQ has been found to result in the halogenation and the anomerization, respectively. Peracetylatedglycosides treaded with I2/TESH or Br2/TESH leading tothe formation of corresponding glycosyl halides, and b-isopropyl glycosidesreacted with Br2/BHQ resulting in the formation of a-glycosides. The anomerizationof glycosidic bond was considered to be catalyzed by in situ formation of hydrogenbromide from the mixing of Br2/BHQ.
- Xu, Lai,Luo, Chin-Hung,Chen, Chien-Sheng
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Read Online
- Neuroprotective activity of different monosaccharide-modified gastrodin analogs
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Gastrodin is a very important and well-known bioactive glycoside compound in Chinese medicine. It is also known as a drug with neuroprotective function. Here, a practical diversified synthesis of a series of gastrodin analogs was reported, which involved four-step procedures consisting of bromination, oxidation, etherification, and reduction. Various gastrodin analogs were obtained in good yields. The compound 4c in this study has a good neuroprotective function: it can significantly downregulate tumor necrosis factor-α and inducible nitric oxide synthase protein levels. The results of this study can provide a research basis for the development of neuroprotective drugs.
- Xu, Kun-Lun,Yu, Lan
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p. 1263 - 1269
(2020/01/21)
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- Total Syntheses of Resin Glycosides Murucoidins IV and v
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Murucoidins IV and V, two bioactive resin glycosides with complex yet similar structures isolated from the morning glory family, were synthesized in a convergent manner. All of the glycosylations in these syntheses including the key [3 + 2] coupling were
- Fang, Jing,Zeng, Jing,Sun, Jiuchang,Zhang, Shuxin,Xiao, Xiong,Lu, Zimin,Meng, Lingkui,Wan, Qian
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supporting information
p. 6213 - 6216
(2019/09/04)
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- Organoboron-Promoted Regioselective Glycosylations in the Synthesis of a Saponin-Derived Pentasaccharide from Spergularia ramosa
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Organoboron-mediated regioselective glycosylations were employed as key steps in the total synthesis of a branched pentasaccharide from a saponin natural product. The ability to use organoboron activation to differentiate OH groups in an unprotected glycosyl acceptor, followed by substrate-controlled reactions of the obtained disaccharide, enabled a streamlining of the synthesis relative to a protective group-based approach. This study revealed a matching/mismatching effect of the relative configuration of donor and acceptor on the efficiency of a regioselective glycosylation reaction, a problem that was solved through the development of a novel boronic acid-amine copromoter system for glycosyl acceptor activation.
- Mancini, Ross S.,McClary, Corey A.,Anthonipillai, Stefi,Taylor, Mark S.
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p. 8501 - 8510
(2015/09/15)
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- Glycosynthase with broad substrate specificity-an efficient biocatalyst for the construction of oligosaccharide library
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A versatile glycosynthase (TnG-E338A) with strikingly broad substrate scope has been developed from Thermus nonproteolyticus β-glycosidase (TnG) by using site-directed mutagenesis. The practical utility of this biocatalyst has been demonstrated by the facile generation of a small library containing various oligosaccharides and a steroidal glycoside (total 25 compounds) in up to 100 % isolated yield. Moreover, an array of eight gluco-oligosaccharides has been readily synthesized by the enzyme in a one-pot, parallel reaction, which highlights its potential in the combinatorial construction of a carbohydrate library that will assist glycomic and glycotherapeutic research. Significantly, the enzyme provides a means by which glycosynthase technology may be extended to combinatorial chemistry.
- Wei, Jinhua,Lv, Xun,Lue, Yang,Yang, Gangzhu,Fu, Lifeng,Yang, Liu,Wang, Jianjun,Gao, Jianhui,Cheng, Shuihong,Duan, Qian,Jin, Cheng,Li, Xuebing
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supporting information
p. 2414 - 2419
(2013/05/23)
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- STEROID COMPOUND
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A steroid compound of the Formula (1): [wherein R1 represents a group selected from the group consisting of H, CH3, C2H5, C3H7 and CH (CH3)2, R2 represents a group selected from NH2, NHAc and OCOR1, R3 represents a group selected from the group consisting of CH3, COOCH3 and CH2OCOR1.]
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Page/Page column 5
(2012/03/26)
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- STEROID COMPOUND
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A steroid compound of the Formula (1): [wherein R1 represents a group selected from the group consisting of H, CH3, C2H5, C3H7 and CH (CH3)2, R2 represents a group selected from NH2, NHAc and OCOR1, R3 represents a group selected from the group consisting of CH3, COOCH3 and CH2OCOR1.]
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Page/Page column 8
(2012/02/04)
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- Total synthesis of ipomoeassin F
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The first total synthesis of ipomoeassin F was carried out using a convergent approach that relied upon the use of Schmidt glycosidation technology for the coupling of two suitably protected monosaccharide fragments. After two steps, ring-closing metathes
- Postema, Maarten H. D.,Tendyke, Karen,Cutter, James,Kuznetsov, Galina,Xu, Qunli
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supporting information; experimental part
p. 1417 - 1420
(2009/10/02)
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- Total synthesis and biological evaluation of the cytotoxic resin glycosides ipomoeassin A-F and analogues
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A multitasking C-silylation strategy using the readily available compound 26 as a surrogate for cinnamic acid represents the key design element of a total synthesis of all known members of the ipomoeassin family of resin glyosides. This protecting group maneuver allows the unsaturated acids decorating the glucose subunit of the targets to be attached at an early phase of the synthesis, prevents their participation in the ruthenium-catalyzed ring-closing metathesis (RCM) used to form the macrocyclic ring, and protects them against reduc tion during the hydrogenation of the resulting cycloalkene over Wilkinson's catalyst. As the C-silyl group can be concomitantly removed with the O-TBS substituent using tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) in acetonitrile, no separate protecting group manipulations were necessary in the final stages, thus contributing to a favorable overall "economy of steps". In addition to the naturally occurring ipomoeassins, a small set of synthetic analogues has also been prepared by "diverted total synthesis". The cytotoxicity of these compounds was assayed with two different cancer cell lines. The recorded data confirm previous findings that the acylation- and oxygenation pattern of these amphiphilic glycoconjugates is highly correlated with their biological activity profile. Ipomoeassin F turned out to be the most promising member of the series, showing IC50 values in the low nanomolar range.
- Nagano, Takashi,Pospisil, Jiri,Chollet, Guillaume,Schulthoff, Saskia,Hickmann, Volker,Moulin, Emilie,Herrmann, Jennifer,Mueller, Rolf,Fuerstner, Alois
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supporting information; experimental part
p. 9697 - 9706
(2010/04/29)
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- Synthesis of per-acetyl D-fucopyranosyl bromide and its use in preparation of diphyllin D-fucopyranosyl glycoside
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The per-O-acetyl-d-fucosyl bromide (9) was expediently prepared for C-6 deoxygenation of d-galactose in six steps in 32.5% yield. Employing phase transfer catalysis glycosylation (PTC), d-fucopyranosyl diphyllin (4), the analog of natural diphyllin glycoside, was synthesized by using 9 as the glycosyl donor in 67.1% in two steps. The product was identified by 1H NMR, 13C NMR, and HRMS. Its abilities to inhibit the growth of cancer cells in vitro also are discussed. Copyright Taylor & Francis Group, LLC.
- Yu, Zhao,Ya-Peng, Lu,Li, Zhu
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p. 113 - 119
(2008/09/21)
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- Total syntheses of ipomoeassin B and E
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A concise, flexible, and efficient total synthesis of the cytotoxic resin glycosides ipomoeassin B (1) and ipomoeassin E (2) is reported which features the advantages of a novel protecting group strategy employing (Z)-3-dimethyl(phenyl)silyl-2-propenoic acid as cinnamic acid surrogate. The use of this readily available compound allowed the macrocycle of the glycolipids to be formed by ring closing olefin metathesis (RCM) with the aid of the second generation Grubbs carbene complex 12. The resulting E/Z mixture could be selectively hydrogenated using Wilkinson's catalyst [RhCl(PPh3)3] without affecting the unsaturated esters in the periphery of the compound, before the C-silyl group was cleaved off with TASF [tris(dimethylamino)sulfonium difluorotrimethylsilicate] under notably mild conditions to release the required cinnamate moiety. Other key steps of the synthesis route comprise the formation of the disaccharide linkage by the trichloroacetimidate method, the formation of the chiral acid segment 19 via a VO(acac)2-catalyzed, tert-BuOOH-induced oxidative rearrangement of the optically pure furyl alcohol (-)-15 (Achmatowicz-type reaction), and a reductive cleavage of the 4,6-O-p-methoxybenzylidene acetal in 5 with NaBH3CN and Me3SiCl (TMSCl), the regiochemical course of which was found to be opposite to that previously reported in the literature for sterically less encumbered substrates. Copyright
- Fuerstner, Alois,Nagano, Takashi
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p. 1906 - 1907
(2007/10/03)
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- A comparative analysis of mono- and disaccharide benzyl fucopyranosides
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The synthesis and x-ray analysis was carried out to compare mono- and disaccharide benzyl fucopyranosides. The molecular structure, hydrogen bonds, intermolecular interactions and crystal structure were described. The different substituents were found to
- Brito-Arias, Marco,Duran-Paramo, Enrique,Mata, Ignasi,Molins, Elies
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p. o537-o539
(2007/10/03)
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- Phenylmethyl 2,3,4-tri-O-acetyl-β-d-fucopyranoside
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The synthesis and X-ray analysis of the title compound is described. The peracetylated benzyl fucopyranoside derivative was prepared by following the classical Koenigs-Knorr methodology. The X-ray diffraction analysis showed a monoclinic system, with a =
- Brito-Arias, Marco,Garcia-Baez, Efren V.,Duran-Paramo, Enrique,Rojas-Lima, Susana
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p. 237 - 241
(2007/10/03)
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- Efficient total syntheses of resin glycosides and analogues by ring-closing olefin metathesis
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A highly efficient entry into the resin glycoside family of natural products is outlined which takes advantage of the inherently modular character of ring-closing metathesis (RCM) for the formation of their macrolactone substructures. Starting from only t
- Fuerstner, Alois,Mueller, Thomas
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p. 7814 - 7821
(2007/10/03)
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- Synthesis of cardenolide glycosides and putative biosynthetic precursors of cardenolide glycosides
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A rapid and efficient procedure for glycosylation of steroids was established using a modified Koenigs-Knorr procedure. Peracetylated β- glycosides were synthesized by reaction of cardenolides, various pregnanes and 23-nor-5,20(22)E-choldienic acid at room temperature with the peracetylated 1-bromo derivatives of D-glucose, D-galactose, D-fucose and cellobiose. Subsequent deprotection was performed by alkaline hydrolysis with sodium methoxide. Structures of the respective glycosides were established by NMR techniques. The complete protocol was shown to be non-destructive at all stages to the sugar moiety and the steroidal nucleus. The γ-unsaturated lactone ring of the cardenolides was shown to remain intact and no formation of C-14 unsaturated compounds was observed.
- Luta, Melitta,Hensel, Andreas,Kreis, Wolfgang
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- SYNTHESIS AND POLYCONDENSATION OF GALACTO-CONFIGURATED MONOMERS VIA THE TRITYL-CYANO-ETHYLIDENE-PROCEDURE
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4-O-Acetyl-1,2--3-O-trityl-α-D-fucopyranose (13) and methyl 4-O-acetyl-1,2-O--3-O-trityl-α-D-galactopyranuronate (14) were synthesised.Trityl-cyanoethylidene condensation of the monomer 14 gave protected β-D-GalpA-(1->3)-D-GalpA-oligosaccharide derivatives with high stereoselectivity and a degree of polymerisation (d.p.) of eight.In the case of the D-fucose monomer 13, the yield of oligomers is surprisingly low and the d.p. does not exceed seven.This result is in contrast to the d.p. 20 - 60 obtained with other 6-deoxy-sugars, as previously described by Kochetkov and coworkers.
- Vogel, Christian,Bergemann, Claudia,Boye, Hanna,Ott, A. Ya.,Betaneli, V. I.,Kochetkov, N. K.
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- Synthesis of uridine 5′(α-D-fucopyranosyl diphosphate) and (digitoxigenin-3β-yl)-β-D-fucopyranoside and enzymatic β-D-fucosylation of cardenolide aglycones in Digitalis lanata
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The phosphorylation of 2,3,4-tri-Oacetyl-α-D-fucopyranose with o-phenylene phosphochloridate yielded α-D-fucopyranosyl phosphate which was used for condensation with undine 5′-monophosphomorpholidate to give uridine 5′-(α-D-fucopyranosyl diphosphate) (UDP-α-D-fucose). A crude enzyme preparation from young leaves of Digitalis lanata EHRH has been shown to catalyze the transfer of D-fucose from synthetic UDP-α-D-fucose to cardenolide aglycones, such as digitoxigenin. The reaction product was identified and characterized by chemical synthesis, HPLC, and spectral methods as the 3 β-O-β-D-fucopyranoside of digitoxigenin (digiproside). Copyright
- Faust,Theurer,Eger,Kreis
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p. 140 - 149
(2007/10/02)
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- Preparation and Antileukemic Screening of Some New 6'-Deoxyhexopyranosyladenine Nucleosides
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9-β-D-Fucopyranosyladenine (1) has weak antileukemic activity against L1210 cells grown in culture.Several new 6'-deoxyhexopyranosyladenine nucleosides were synthesized by standard procedures and assayed for activity.The new nucleosides were 9-(6-deoxy-β-
- Lerner, Leon M.,Sheid, Bertrum,Gaetjens, Eric
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p. 1521 - 1525
(2007/10/02)
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- DERIVATIVES OF 6-DEOXY-L-TALOSE AND THE SYNTHESIS OF 6-DEOXY-2-O-(α-L-RHAMNOPYRANOSYL)-L-TALOSE
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Benzyl 6-deoxy-α-L-talopyranoside (10) has been synthesized and provides, after hydrogenolysis, an improved preparation of 6-deoxy-L-talose.Several partially substituted derivatives of the glycoside 10 have been prepared, including benzyl 6-deoxy-3,4-O-is
- Aspinall, Gerald O.,Takeo, Ken'ichi
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- Synthesis and antitumor activity of analogues of the antitumor antibiotic chartreusin
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First isolated in 1953 from a fermentation broth, chartreusin (1) has received interest as a result of substantial antitumor activities recently demonstrated in several murine test systems. Poor water solubility frustrated formulation attempts, and rapid
- Takai,Uehara,Beisler
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p. 549 - 553
(2007/10/02)
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