- Synthesis of Branched Tetrasaccharide Derivatives of Schizophyllan-like β-Glucan
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Branched tetrasaccharide derivatives as the repeating units of schizophyllan were synthesized using a common intermediate that had different protecting groups on the hydroxyl groups. Accordingly, β-1,3-disaccharide acceptors were efficiently glycosylated
- Miyagawa, Atsushi,Matsuda, Tomoka,Yamamura, Hatsuo
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- Photooxidation of thiosaccharides mediated by sensitizers in aerobic and environmentally friendly conditions
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A series of β-d-glucopyranosyl derivates have been synthesized and evaluated in photooxidation reactions promoted by visible light and mediated by organic dyes under aerobic conditions. Among the different photocatalysts employed, tetra-O-acetyl riboflavin afforded chemoselectively the respective sulfoxides, without over-oxidation to sulfones, in good to excellent yields and short reaction times. This new methodology for the preparation of synthetically useful glycosyl sulfoxides constitutes a catalytic, efficient, economical, and environmentally friendly oxidation process not reported so far for carbohydrates.
- Traverssi, Miqueas G.,Pe?é?ory, Alicia B.,Varela, Oscar,Colomer, Juan P.
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p. 9262 - 9273
(2021/03/16)
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- Organophotoredox-Catalyzed Formation of Alkyl-Aryl and -Alkyl C-S/Se Bonds from Coupling of Redox-Active Esters with Thio/Selenosulfonates
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A mild organophotoredox synthetic protocol for forming a Csp3-S/Se bond by reacting widespread redox-active esters with thio/selenosulfonates has been developed. The power of the synthetic manifold is fueled by an unprecedented broad substrate scope and wide functional group tolerance.
- Dong, Yue,Ji, Peng,Zhang, Yueteng,Wang, Changqing,Meng, Xiang,Wang, Wei
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p. 9562 - 9567
(2021/01/09)
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- Direct, stereoselective thioglycosylation enabled by an organophotoredox radical strategy
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While strategies involving a 2e- transfer pathway have dictated glycosylation development, the direct glycosylation of readily accessible glycosyl donors as radical precursors is particularly appealing because of high radical anomeric selectivity and atom- and step-economy. However, the development of the radical process has been challenging owing to notorious competing reduction, elimination and/or SN side reactions of commonly used, labile glycosyl donors. Here we introduce an organophotocatalytic strategy through which glycosyl bromides can be efficiently converted into corresponding anomeric radicals by photoredox mediated HAT catalysis without a transition metal or a directing group and achieve highly anomeric selectivity. The power of this platform has been demonstrated by the mild reaction conditions enabling the synthesis of challenging α-1,2-cis-thioglycosides, the tolerance of various functional groups and the broad substrate scope for both common pentoses and hexoses. Furthermore, this general approach is compatible with both sp2 and sp3 sulfur electrophiles and late-stage glycodiversification for a total of 50 substrates probed.
- Bi, Fangchao,Gao, Feng,Ji, Peng,Wang, Wei,Zhang, Yueteng
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p. 13079 - 13084
(2021/01/09)
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- Synthesis of O-1- O-6 Substituted Positional Isomers of d -Glucose-Thioether Ligands and Their Ruthenium Polypyridyl Conjugates
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A library of positional isomers of d-glucose (O-1-O-6) as ligands and their 11 light-active ruthenium conjugates has been synthesized. A protecting group strategy without the necessity of using palladium on carbon for the modification for the 2-O and 4-O position allows for the incorporation of sulfur donor atoms as ligands for transition metal complexes.
- Lameijer, Lucien N.,Le Roy, Julien,Van Der Vorm, Stefan,Bonnet, Sylvestre
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p. 12985 - 12997
(2018/11/20)
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- Interrupted Pummerer Reaction in Latent-Active Glycosylation: Glycosyl Donors with a Recyclable and Regenerative Leaving Group
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Latent O-glycosides, 2-(2-propylthiol)benzyl (PTB) glycosides, were converted into the corresponding active glycosyl donors, 2-(2-propylsulfinyl)benzyl (PSB) glycosides, by a simple and efficient oxidation. Treatment of the PSB donor and various acceptors with triflic anhydride provided the desired glycosides in good to excellent yields. The leaving group, which was activated by an interrupted Pummerer reaction, can be recycled (PSB-OH) and regenerated as the precursor (PTB-OH). A natural hepatoprotective glycoside, leonoside F, was efficiently synthesized in a convergent [3+1] manner with this newly developed method. The present total synthesis also led to a structural revision of this phenylethanoid glycoside.
- Shu, Penghua,Xiao, Xiong,Zhao, Yueqi,Xu, Yang,Yao, Wang,Tao, Jinyi,Wang, Hao,Yao, Guangmin,Lu, Zimin,Zeng, Jing,Wan, Qian
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supporting information
p. 14432 - 14436
(2016/01/25)
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- Acyl transfer reactions of carbohydrates, alcohols, phenols, thiols and thiophenols under green reaction conditions
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Acyl transfer reactions of various carbohydrates, alcohols, phenols, thiols and thiophenols were achieved at room temperature in high yields and catalytic efficiency in the presence of methane sulfonic acid, a green organic acid, under solvent-free conditions over short time periods. The method is mild enough to allow acid labile substituents such as isopropylidene acetals and trityl ethers on the reacting substrates to be left completely unaffected. Esterification of free mono- and dicarboxylic acids such as acetic acid, cinnamic acid, sialic acid and tartaric acid with alcohols such as menthol, ethanol, methanol or propylene glycol has also been achieved efficiently at room temperature. A comparative study of the method with the silica-sulfuric acid is also reported.
- Giri, Santosh Kumar,Kartha, K. P. Ravindranathan
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p. 11687 - 11696
(2015/02/19)
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- The Glc2Man2-fragment of the N-glycan precursor - A novel ligand for the glycan-binding protein malectin?
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The Glcα(1→3)Glcα(1→3)Manα(1→2)Man tetrasaccharide (Glc2Man2-fragment), a substructure of the natural N-glycan precursor, was synthesized. The interaction of this fragment with the protein malectin, a carbohydrate binding protein localized in the endoplasmatic reticulum, was investigated by 1H15N HSQC experiments and isothermal calorimetry. The chemical shift perturbations of nuclei in the protein's backbone caused by the binding of the Glc 2Man2-fragment to malectin suggest a binding mode like the known ligand nigerose. The Royal Society of Chemistry 2010.
- Mueller, Lisa N.,Muhle-Goll, Claudia,Biskup, Moritz B.
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supporting information; experimental part
p. 3294 - 3299
(2010/08/21)
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- Synthetic studies on pterin glycosides: the first synthesis of 2′-O-(α-d-glucopyranosyl)biopterin
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l-Rhamnose was led, in a 14-step-sequence, to N2-(N,N-dimethylaminomethylene)-1′-O-(4-methoxybenzyl)-3-[2-(4-nitrophenyl)ethyl]biopterin (23), an appropriately protected precursor for 2′-O-glycosylation, while 4,6-di-O-acetyl-2,3-di-O-(4-methox
- Hanaya, Tadashi,Baba, Hiroki,Toyota, Hiroki,Yamamoto, Hiroshi
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experimental part
p. 7989 - 7997
(2009/12/03)
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- First synthesis of biopterin α-D-glucoside
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A novel glycosyl donor, 4,6-di-O-acetyl-2,3-di-O-(4-methoxybenzyl)-α- D-glucopyranosy bromide (15) was efficiently prepared from D-glucose in 8 steps. The first synthesis of 2'-O-(α-D-glucopyranosyl)biopterin (2) was achieved by treatment of the key precursor, N2-(N,N- dimethylaminomethylene)-1'-O-(4-methoxybenzyl)-3-[2-(4-nitrophenyl)ethyl] biopterin (6) with 15 in the presence of silver triflate and tetramethylurea, followed by removal of the protecting groups.
- Hanaya, Tadashi,Baba, Hiroki,Yamamoto, Hiroshi
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scheme or table
p. 747 - 753
(2010/09/15)
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- Involvement of the S-aglycon in the conformational preferences of thioglucosides
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The conformational preferences of two series of alkyl β-d-thioglucopyranosides in solution were investigated by NMR and CD. The rotamer populations of the hydroxymethyl group were found to depend on the structural nature of the S-aglycon. The population of the gt rotamer increased and that of the gg rotamer decreased as the alkyl group attached to the S atom increased in size. These rotamer populations have a linear correlation with the Taft' steric parameters, the nS s(-) σC s(-) O* exo-anomeric interaction may express these rotational preferences. Comparative analysis of the hydroxymethyl populations between alkyl O- and S-glucosides revealed identical or slightly higher gt and smaller gg populations for the latter compounds.
- Sanhueza, Carlos A.,Dorta, Rosa L.,Vazquez, Jesus T.
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p. 258 - 264
(2008/09/19)
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- Novel approaches for the synthesis and activation of thio- and selenoglycoside donors
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(Chemical Equation Presented) Alkyl thio-, phenyl seleno-, and phenyl thioglycosides can be prepared through short synthetic sequences based on the generation of glycosyl iodides as versatile intermediates. In addition, a novel cheap combined system (stoichiometric NBS and catalytic Bi(OTf)3) has been developed for rapid and efficient activation of a wide variety of thio- and selenoglycoside donors.
- Valerio, Silvia,Iadonisi, Alfonso,Adinolfi, Matteo,Ravida, Alessandra
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p. 6097 - 6106
(2008/02/09)
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- High throughput screening of O-glycosylation conditions
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We report a novel methodology for rapid and quantitative screening of O-glycosylation reactions of application to the analysis of parallel reaction systems. Our system exploits perdeuterated benzyl (Bn-d7) ether, and stereoselectivity and yield
- Ishiwata, Akihiro,Ito, Yukishige
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p. 3521 - 3524
(2007/10/03)
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- Streamlined synthesis of per-O-acetylated sugars, glycosyl iodides, or thioglycosides from unprotected reducing sugars
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Solvent-free per-O-acetylation of sugars with stoichiometric acetic anhydride and catalytic iodine proceeds in high yield (90-99%) to give exclusively pyranose products as anomeric mixtures. Without workup, subsequent anomeric substitution employing iodine in the presence of hexamethyldisilane (i.e., TMS-I generated in situ) gives the corresponding glycosyl iodides in 75-95% isolated yield. Alternatively, and without workup, further treatment with dimethyl disulfide or thiol (ethanethiol or thiocresol) gives anomerically pure thioglycosides in more than 75% overall yield.
- Mukhopadhyay, Balaram,Kartha, K.P. Ravindranathan,Russell, David A.,Field, Robert A.
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p. 7758 - 7760
(2007/10/03)
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- Reaction of 1,2-trans-glycosyl acetates with thiourea: A new entry to 1-thiosugars
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The reaction of 1,2-trans-glycosyl acetates with thiourea under boron trifluoride etherate catalysis affording acetylated S-glycosyl isothiourea derivatives is described. The isothiourea derivatives obtained can be readily transformed into the desired 1-thiosugar derivative by reaction with triethylamine and subsequent alkylation or acylation of the in situ formed 1-thioaldose.
- Ibatullin, Farid M.,Shabalin, Konstantin A.,J?nis, Janne V.,Shavva, Alexander G.
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p. 7961 - 7964
(2007/10/03)
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- Iodine and its interhalogen compounds: Versatile reagents in carbohydrate chemistry v. synthesis of 1,2-trans-linked 1-thioglycosides from the per-o-acetylated glycoses
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Treatment of per-O-acetylated mono- and di-saccharides with (alkyl/arylthio)trimethylsilane and iodine at ambient temperature results in the formation of the corresponding 1,2-trans-1-thioglycosides in very high yield. In the case of higher boiling thiols such as ethanethiol, the reaction can be effectively carried out in the presence of the thiol itself instead of the silylated derivative, but the reaction is not stereospecific. Moreover, in the latter reactions a portion of the starting material remains unchanged even on prolonged reaction. With β-D-glucose pentaacetate (11) as the starting material, its epimerisation occurred during the reaction and therefore the recovered starting material was of α-D-configuration. In addition, the methyl disulphide-hexamethyldisilane system has been found to serve as an effective and cheaper alternative to the expensive (methylthio)-trimethylsilane.
- Kartha, K. P. Ravindranathan,Field, Robert A.
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p. 693 - 702
(2007/10/03)
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- Chemical synthesis of 13C-labelled ganglioside Gb3 trisaccharide from [U-13C]-D-glucose
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The interaction of bacterial toxins with their cell surface glycolipid receptors offers scope for therapeutic intervention. Whilst crystal and solution structures of Escherichia coli verotoxin-1 have been reported, the precise nature of the interaction of
- Shimizu, Hiroki,Brown, Jonathan M.,Homans, Steven W.,Field, Robert A.
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p. 9489 - 9506
(2007/10/03)
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- Reaction of sugar thiocyanates with Grignard reagents. New synthesis of thioglycosides
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Glycosyl thiocyanates having hydroxyl groups protected with acetyl or benzoyl groups react readily at -40°C with Grignard reagents to afford the corresponding alkyl or aryl thioglycosides in good yields. Monosaccharide derivatives having the SCN grouping at other positions form under similar conditions thioethers. Axial thiocyanates do not react. Elevated temperatures induce side reactions leading to mercaptans.
- Pakulski, Zbigniew,Pierozynski, Donat,Zamojski, Aleksander
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p. 2975 - 2992
(2007/10/02)
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- Synthesis of Oligosaccharides Corresponding to the Common Polysaccharide Antigen of Group B Streptococci
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To facilitate mapping of the immunodominant region of the common polysaccharide antigen of group B streptococci, tetrasaccharide 1-O--α-rhamnopyranosyl>-D-glucitol (2) was synthesized in a stepwise fasion
- Pozsgay, Vince,Jennings, Harold J.
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p. 4042 - 4052
(2007/10/02)
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- SYNTHESES OF A BRANCHED HEPTASACCHARIDE HAVING PHYTOALEXIN-ELICITOR ACTIVITY
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Synteses are described of a D-glucose heptasaccharide, 1, corresponding to a glucan structure recognised by the soybean when infected by the fungus Phytophtora megasperma f. sp. glycinea and which stimulates the formation of phytoalexins.The synthetic strategy is based upon 1,2-trans-glycoside formation assisted by participating benzoate groups in the 2-position, with silver triflate as promoter and glycosyl bromides as donors for making the smaller fragments, and with methyl triflate as promoter with thioglycosides as donors for making the larger ones.Regioselective reductive openings of 4,6 benzylidene acetals play a key role in obtaining free 6-OH groups with benzyl protection at O-4.
- Fuegedi, Peter,Birberg, Winnie,Garegg, Per J.,Pilotti, Ake
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p. 297 - 312
(2007/10/02)
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- Synthetic Studies on Rhynchosporoside and Related Substances
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The stereoselective synthesis of the 1-O-α-D-glucopyranosides and 1-O-α-D-cellobiosides of 3-deoxy-2(R)- and 2(S)-glycerols to determine the complete stereochemistry of rhynchosporoside, which is a host selective phytotoxin from Rhynchosporium secalis, is
- Sugawara, Fumio,Nakayama, Haruhiko,Strobel, Gary A.,Ogawa, Tomoya
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p. 2251 - 2260
(2007/10/02)
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- A Through-process for the Preparation of Methyl Per-O-acetyl 1-Thio-glycosides from Aldoses
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D-Glucose, D-galactose, D-mannose, D-xylose, L-arabinose, L-fucose, L-rhamnose, maltose, cellobiose, lactose, D-glucosamine, D-galactosamine, and D-mannosamine were converted into the corresponding methyl per-O-acetyl 1-thioglycopyranosides by way of a three-step (acetobromination, methylthioation, and acetylation) through-process in a single vessel.
- Koto, Shinkiti,Yoshida, Toyosaku,Takenaka, Kazuhiro,Zen, Shonosuke
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p. 3667 - 3668
(2007/10/02)
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