- Automated access to well-defined ionic oligosaccharides
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Ionic polysaccharides are part of many biological events, but lack structural characterisation due to challenging purifications and complex synthesis. Four monosaccharides bearing modifications not found in nature are used for the automated synthesis of a collection of ionic oligosaccharides. Structural analysis reveals how the charge pattern affects glycan conformation.
- Delbianco, Martina,Grafmüller, Andrea,Schiefelbein, Kevin,Seeberger, Peter H.,Tyrikos-Ergas, Theodore,Zhu, Yuntao
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supporting information
p. 1349 - 1353
(2020/03/03)
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- One-Pot Relay Glycosylation
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A novel one-pot relay glycosylation has been established. The protocol is characterized by the construction of two glycosidic bonds with only one equivalent of triflic anhydride. This method capitalizes on the in situ generated cyclic-thiosulfonium ion as the relay activator, which directly activates the newly formed thioglycoside in one pot. A wide range of substrates are well-accommodated to furnish both linear and branched oligosaccharides. The synthetic utility and advantage of this method have been demonstrated by rapid access to naturally occurring phenylethanoid glycoside kankanoside F and resin glycoside merremoside D.
- Cai, Lei,Fang, Jing,Li, Ting,Song, Zejin,Sun, Jiuchang,Wan, Qian,Xiao, Xiong,Zeng, Jing
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p. 5498 - 5503
(2020/04/09)
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- Synthesis of Glucuronoxylan Hexasaccharides by Preactivation-Based Glycosylations
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The synthesis of two glucuronoxylans is described, which both consist of a pentaxylan backbone and a glucuronic acid linked to the 2 position in the fourth xylose residue from the reducing end. The two target molecules differ in the 4 position of the glucuronic acid where one is unsubstituted while the other contains a methyl ether. The pentaxylan backbone is assembled in four glycosylation reactions with phenyl thioglycoside donors. The couplings are performed by preactivation of the donor with in-situ-generated p-nitrobenzenesulfenyl triflate prior to addition of the acceptor. The glucuronic acids are then attached by Koenigs-Knorr glycosylations followed by deprotections. The syntheses employ a total of 8 steps from monosaccharide building blocks and afford the two glucuronoxylans in 12 and 15 % overall yield. The hexasaccharide products are valuable substrates for investigating the activity and specificity of glucuronoxylan-degrading enzymes.
- B?hm, Maximilian,Madsen, Robert,Underlin, Emilie N.,d'Errico, Clotilde
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supporting information
(2020/05/16)
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- A Sugar-Based Gelator for Marine Oil-Spill Recovery
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Marine oil spills constitute an environmental disaster with severe adverse effects on the economy and ecosystem. Phase-selective organogelators (PSOGs), molecules that can congeal oil selectively from oil–water mixtures, have been proposed to be useful for oil-spill recovery. However, a major drawback lies in the mode of application of the PSOG to an oil spill spread over a large area. The proposed method of using carrier solvents is impractical for various reasons. Direct application of the PSOG as a solid, although it would be ideal, is unknown, presumably owing to poor dispersion of the solid through the oil. We have designed five cheap and easy-to-make glucose-derived PSOGs that disperse in the oil phase uniformly when applied as a fine powder. These gelators were shown to selectively congeal many oils, including crude oil, from oil–water mixtures to form stable gels, which is an essential property for efficient oil-spill recovery. We have demonstrated that these PSOGs can be applied aerially as a solid powder onto a mixture of crude oil and sea water and the congealed oil can then be scooped out. Our innovative mode of application and low cost of the PSOG offers a practical solution to oil-spill recovery.
- Vibhute, Amol M.,Muvvala, Venkatanarayana,Sureshan, Kana M.
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supporting information
p. 7782 - 7785
(2016/07/07)
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- Efficient one-pot per-: O -acetylation-thioglycosidation of native sugars, 4,6- O -arylidenation and one-pot 4,6- O -benzylidenation-acetylation of S -/ O -glycosides catalyzed by Mg(OTf)2
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A sequential one-pot per-O-acetylation-S-/O-glycosidation of native mono and disaccharides under solvent free conditions using 0.5 mole% of Mg(OTf)2 as a non-hygroscopic, recyclable catalyst is reported. Regioselective 4,6-O-arylidenation of glycosides and thioglycosides with benzaldehyde or p-methoxybenzaldehyde dimethyl acetal is catalyzed by 10 mole% of Mg(OTf)2 to produce the corresponding 4,6-O-arylidenated product in high yields. Mg(OTf)2 can also mediate sequential one-pot benzylidenation-acetylation of mono and disaccharide based glycosides and thioglycosides in high yield.
- Mukherjee, Mana Mohan,Basu, Nabamita,Chaudhury, Aritra,Ghosh, Rina
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p. 109301 - 109314
(2016/11/30)
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- Three Solvent-Free Catalytic Approaches to the Acetal Functionalization of Carbohydrates and Their Applicability to One-Pot Generation of Orthogonally Protected Building Blocks
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Three alternative protocols were developed to carry out the selective installation of acetal groups on carbohydrates and polyols under mildly acidic, solvent-free conditions. One protocol is based on a diol/aldehyde condensation at room temperature, with an acetolysis process serving for the activation of the carbonyl component. A second approach is based on an orthoester-mediated activation of the carbonyl component at high temperature. The third protocol is instead entailing a transacetalation mechanism. Combination of these methods allows a wide set of acetal-protected building blocks to be accessed in short times under very simple experimental conditions working under air. The scope of the latter two approaches was also extended to unusual one-pot synthetic sequences leading to concomitant Fischer glycosidation/acetal protection of reducing sugars.
- Traboni, Serena,Bedini, Emiliano,Giordano, Maddalena,Iadonisi, Alfonso
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p. 3562 - 3572
(2016/01/25)
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- Exploring glycosylation reactions under continuous-flow conditions
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The industrial development of carbohydrate-based drugs is greatly thwarted by the typical challenges inherent in oligosaccharide synthesis. The practical advantages of continuous-flow synthesis in microreactors (high reproducibility, easy scalability, and fast reaction optimization) may offer an effective support to make carbohydrates more attractive targets for drug-discovery processes. Here we report a systematic exploration of the glycosylation reaction carried out under microfluidic conditions. Trichloroacetimidates and thioglycosides have been investigated as glycosyl donors, using both primary and secondary acceptors. Each microfluidic glycosylation has been compared with the corresponding batch reaction, in order to highlight advantages and drawbacks of microreactors technology. As a significant example of multistep continuous-flow synthesis, we also describe the preparation of a trisaccharide by means of two consecutive glycosylations performed in interconnected microreactors.
- Cancogni, Damiano,Lay, Luigi
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p. 2873 - 2878
(2015/01/16)
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- High-yield total synthesis of (-)-strictinin through intramolecular coupling of gallates
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This paper describes a total synthesis of (-)-strictinin, an ellagitannin that is 1-O-galloyl-4,6-O-(S)-hexahydroxydiphenoyl (HHDP)-β-d-glucose. In the study, total efficiency of the synthesis was improved to produce a 78% overall yield in 13 steps from d-glucose. In the synthesis, formation of the 4,6-(S)-HHDP bridge including the 11-membered bislactone ring was a key step, in which intramolecular aryl-aryl coupling was adopted. The coupling was oxidatively induced by CuCl2-n-BuNH2 with perfect control of the axial chirality, and the reaction conditions of this coupling were optimized thoroughly to achieve the quantitative formation of the bridge.
- Michihata, Naoki,Kaneko, Yuki,Kasai, Yusuke,Tanigawa, Kotaro,Hirokane, Tsukasa,Higasa, Sho,Yamada, Hidetoshi
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p. 4319 - 4328
(2013/06/27)
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- 'Naked' and hydrated conformers of the conserved core pentasaccharide of N-linked glycoproteins and its building blocks
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N-glycosylation of eukaryotic proteins is widespread and vital to survival. The pentasaccharide unit -Man3GlcNAc2- lies at the protein-junction core of all oligosaccharides attached to asparagine side chains during this process. Although its absolute conservation implies an indispensable role, associated perhaps with its structure, its unbiased conformation and the potential modulating role of solvation are unknown; both have now been explored through a combination of synthesis, laser spectroscopy, and computation. The proximal -GlcNAc-GlcNAc- unit acts as a rigid rod, while the central, and unusual, -Man-β-1,4-GlcNAc- linkage is more flexible and is modulated by the distal Man-α-1,3- and Man-α-1,6- branching units. Solvation stiffens the 'rod' but leaves the distal residues flexible, through a β-Man pivot, ensuring anchored projection from the protein shell while allowing flexible interaction of the distal portion of N-glycosylation with bulk water and biomolecular assemblies.
- Barry, Conor S.,Cocinero, Emilio J.,Carcabal, Pierre,Gamblin, David P.,Stanca-Kaposta, E. Cristina,Remmert, Sarah M.,Fernandez-Alonso, Maria C.,Rudic, Svemir,Simons, John P.,Davis, Benjamin G.
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p. 16895 - 16903
(2013/12/04)
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- Contribution of phosphates and adenine to the potency of adenophostins at the IP3 receptor: Synthesis of all possible bisphosphates of adenophostin A
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Although adenophostin A (AdA), the most potent agonist of d-myo-inositol 1,4,5-trisphosphate receptors (IP3R), is thought to mimic IP 3, the relative roles of the different phosphate groups and the adenosine motif have not been established. We synthesized all three possible bisphosphate analogues of AdA and glucose 3,4-bisphosphate (7, AdA lacking the 2′-AMP). 2′-Dephospho-AdA (6) was prepared via a novel regioselective dephosphorylation strategy. Assessment of the abilities of these bisphosphates to stimulate intracellular Ca2+ release using recombinant rat type 1 IP3R (IP3R1) revealed that 6, a mimic of Ins(4,5)P2, is only 4-fold less potent than IP3, while 7 is some 400-fold weaker and even 3′3-dephospho-AdA (5) is measurably active, despite missing one of the vicinal bisphosphate groups normally thought to be crucial for IP3-like activity. Compound 6 is the most potent bisphosphate yet discovered with activity at IP3R. Thus, adenosine has a direct role independent of the 2′-phosphate group in contributing toward the potency of adenophostins, the vicinal bisphosphate motif is not essential for activity at the IP3R, as always thought, and it is possible to design potent agonists with just two of the three phosphates. A model with a possible adenine-R504 interaction supports the activity of 5 and 6 and also allows a reappraisal of the unexpected activity previously reported for the AdA regioisomer 2′3-phospho-3′3- dephospho-AdA 40.
- Sureshan, Kana M.,Riley, Andrew M.,Thomas, Mark P.,Tovey, Stephen C.,Taylor, Colin W.,Potter, Barry V. L.
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p. 1706 - 1720
(2012/05/04)
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- Preparation of Thiosugars and Their Use
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A process for the preparation of a thiosaccharide represented by Saccharide-S-H wherein Saccharide comprises at least 4 sugar units, comprises subjecting a corresponding compound of the formula (P)Saccharide-S-(P) wherein (P) represents an O- or S-protecting group(s), to Birch reduction.
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Page/Page column 8; 19
(2009/07/18)
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- Modular synthesis of heparan sulfate oligosaccharides for structure-activity relationship studies
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Although hundreds of heparan sulfate binding proteins have been identified and implicated in a myriad of physiological and pathological processes, very little information is known about the ligand requirements for binding and mediating biological activiti
- Arungundram, Sailaja,Al-Mafraji, Kanar,Asong, Jinkeng,Leach III, Franklin E.,Amster, I. Jonathan,Venot, Andre,Turnbull, Jeremy E.,Boons, Geert-Jan
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scheme or table
p. 17394 - 17405
(2010/03/23)
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- Synthesis and cytotoxicities of icogenin analogues with disaccharide residues
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For further structure-activity relationships (SAR) research of furostan saponin, two icogenin analogues: (25R)-22-O-methyl-furost-5-en-3β,26-diol-3-O-α-l-rhamnopyrano syl-(1 → 2)-β-d-glucopyranoside 1 and (25R)-22-O-methyl-furost-5-en-3β,26-diol-3-O-α-l-r
- Wang, Haixing,Su, Fuqin,Zhou, Liang,Chen, Xiaoguang,Lei, Pingsheng
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scheme or table
p. 2796 - 2800
(2010/04/05)
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- Cu(OTf)2-catalyzed Et3SiH-reductive etherification of various carbonyl compounds with trimethylsilyl ethers
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A triethylsilane-reductive etherification of the trimethylsilyl ethers with a variety of carbonyl compounds in good yields at room temperature employing 0.5 mol% Cu(OTf)2 as an extremely efficient catalyst is described here.
- Yang, Wei-Chieh,Lu, Xin-An,Kulkarni, Suvarn S.,Hung, Shang-Cheng
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p. 7837 - 7840
(2007/10/03)
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- Synthesis of neomycin analogs to investigate aminoglycoside-RNA interactions
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A series of novel aminoglycoside oligosaccharide analogs containing a 2,5-dideoxystreptamine core scaffold was prepared to study aminoglycoside binding to the small subunit of 16S rRNA. A set of monosaccharide building blocks carrying amino groups in diff
- Seeberger, Peter H.,Baumann, Michael,Zhang, Guangtao,Kanemitsu, Takuya,Swayze, Eric E.,Hofstadler, Steven A.,Griffey, Richard H.
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p. 1323 - 1326
(2007/10/03)
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- Rapid carbohydrate protecting group manipulations assisted by microwave dielectric heating
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The protocols for oligosaccharide synthesis are often tedious due to extended synthetic routes and reaction times. We herein describe methods assisted by microwave dielectric heating, which enable very short reaction times and high yields for the introduction and removal of eleven of the most commonly used protecting groups in carbohydrate syntheses. Several examples are reported, where solid supported reagents in combination with microwave dielectric heating have been used. This results in both faster and easier synthesis and purification.
- Soederberg, Eva,Westman, Jacob,Oscarson, Stefan
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p. 397 - 410
(2007/10/03)
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- Synthesis of disaccharides containing α-linked GlcNAc or β-linked ManNAc units
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The synthesis of disaccharides containing α-linked GlcNAc or β-linked ManNAc units from shelf-stable, and yet highly reactive, 2-oximinoglycosyl donors is described. Access to a preponderance of the disaccharide containing either the α-linked GlcNAc or β-linked ManNAc unit can be obtained by careful choice of solvent and glycosidation conditions.
- Ennis,Gridley,Osborn,Spackman
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p. 1593 - 1596
(2007/10/03)
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- Regioselective Lipase-catalysed acylation of 4,6-O-benzylidene-α- and - β-D-pyranoside derivatives displaying a range of anomeric substituents
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The application of Lipase enzymes to effect regioselective C-3-O- acylation of 4,6-O-benzylidene-β-D-gluco- and -galactopyranosides displaying a range of anomeric substituents, and C-2-O-acylation of phenyl 4,6-O- benzylidene-α-D-glucopyranoside and ethyl 4,6-O-benzylidene-1-thio-α-D- glucopyranoside is reported. In particular this method has allowed introduction of a variety of acyl protecting groups at the C-3 hydroxyl group of ethyl 4,6-O-benzylidene-1-thio-β-D-glucopyranoside 11.
- Gridley, Jonathan J.,Hacking, Andrew J.,Osborn, Helen M. I.,Spackman, David G.
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p. 14925 - 14946
(2007/10/03)
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- Total synthesis of tricolorin A
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Tricolorin A (1), a structurally amazing resin glycoside with promising bioactivities from Ipomoea tricolor cav. (convolvulaceae), was synthesized in a total of 45 steps, with the longest linear sequence of 20 steps and overall yield of 0.65% from D-mannitol. The AB disscharide 19-membered lactone 2 was constructured by a regioselective macrolactonization using Corey-Nicolaou protocol. The macrolactone tetrasaccharide 33 was realized either by 'one- pot two-step' glycosylation procedure or by a stepwise assembly employing the 'armed-disarmed' glycosylation strategy.
- Lu, Shou-Fu,O'Yang, QinQin,Guo, Zhong-Wu,Yu, Biao,Hui, Yong-Zheng
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p. 8400 - 8405
(2007/10/03)
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- Regioselective lipase-catalysed acylation of 4,6-O-benzylidene-β-D-pyranoside derivatives displaying a range of anomeric substituents
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The application of lipase enzymes to effect regioselective C-3-O-acylation of 4,6-O-benzylidene-β-D-gluco- and galactopyranosides displaying a range of anomeric substituents is reported. In particular this method has allowed introduction of a variety of acyl protecting groups at the C-3 hydroxyl group of ethyl 4,6-O-benzylidene-1-thio-β-D-glucopyranoside 9.
- Gridley, Jonathan J.,Hacking, Andrew J.,Osborn, Helen M. I.,Spackman, David G.
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p. 1397 - 1399
(2007/10/03)
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- The First Total Synthesis of Tricolorin A
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Keywords: glycosylations; macrocycles; one-pot reactions; total synthesis; tricolorin A
- Lu, Shou-Fu,O'yang, QinQin,Guo, Zhong-Wu,Yu, Biao,Hui, Yong-Zheng
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p. 2344 - 2346
(2007/10/03)
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- The Stereoselective Synthesis of Cyclomaltopentaose. A Novel Cyclodextrin Homologue with D.P. Five.
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A key intermediate 15 was prepared via successive glycosidations of 1,6-anhydro maltose derivative 8 with glycosyl donors 6 and then with 11, cyclized under a diluted condition, and deprotected to give the title compound.Every glycosidation, including the
- Nakagawa, Toshio,Ueno, Koji,Kashiwa, Mariko,Watanabe, Junko
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p. 1921 - 1924
(2007/10/02)
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- Synthesis of a Methyl Heptaglucoside: Analogue of the Phytoalexin Elicitor from Phytophtora Megasperma
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The ethylthio-laminaribioside 29, prepared by regiospecific glycosylation of ethyl 4,6-O-benzylidene-1-thio-β-D-glucopyranoside (9) with 2,3,4,6-tetra-O-benzoyl-D-glucopyranosyl imidate 17 and subsequent benzoylation, could be elongated in a step-wise fas
- Verduyn, R.,Douwes, M.,Klein, P.A.M. van der,Moesinger, E.M.,Marel, G.A. van der,Boom, J.H. van
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p. 7301 - 7316
(2007/10/02)
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- Synthesis of trisaccharide methyl glycosides related to fragments of the capsular polysaccharide of Streptococcus pneumoniae type 18C
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The synthesis is reported of methyl 3-0-(4-0-β-D-galactopyranosyl-α-D-glucopyranosyl)-α-L- rhamnopyranoside (1), methyl 2-0-α-D-glucopyranosyl-4-0-β-D-glucopyranosyl-β-D- galactopyranoside (3), methyl 3-0-(4-0-β-D-galactopyranosyl-α-D-glucopyranosyl)-α-L-
- Van Steijn,Kamerling,Vliegenthart
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p. 229 - 245
(2007/10/02)
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