- Synthesis of blood group A and B (type 2) tetrasaccharides. A strategy with fucosylation at the last stage
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The traditionally used strategy for the synthesis of blood group A and B tetrasaccharides includes 2′-O-fucosylation of lactosamine followed by insertion of an α1-3 linked N-acetylgalactosamine or a galactose moiety. Here, we report the synthesis of 3-aminopropyl glycosides of A (type 2) and B (type 2) tetrasaccharides via an alternative sequence, i.e. α-galactosaminylation (or α-galactosylation) followed by α-fucosylation. This strategy allows us to synthesize fucose-free trisaccharides GalNAcα1-3Galβ1-4GlcNAc and Galα1-3Galβ1-4GlcNAc, which are promising targets for immunotherapy utilising human natural antibodies against the trisaccharides. The key stage in this scheme was the selective chloroacetylation of the 2′-OH group of βGal in the intermediate trisaccharides having the second (3-OH) unprotected group.The protocol is suitable for multigram syntheses and its further scaling up.
- Kunetskiy, Roman A.,Pazynina, Galina V.,Ivanov, Igor A.,Bovin, Nicolai V.
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- Bismuth(iii) triflate as a novel and efficient activator for glycosyl halides
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Presented herein is the discovery that bismuth(iii) trifluoromethanesulfonate (Bi(OTf)3) is an effective catalyst for the activation of glycosyl bromides and glycosyl chlorides. The key objective for the development of this methodology is to em
- Steber, Hayley B.,Singh, Yashapal,Demchenko, Alexei V.
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p. 3220 - 3233
(2021/04/21)
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- Stereocontrolled α-Galactosylation under Cooperative Catalysis
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A recent discovery of a cooperative catalysis comprising a silver salt and an acid led to a dramatic improvement in the way glycosyl halides are glycosidated. Excellent yields have been achieved, but the stereoselectivity achieved with 2-O-benzylated donors was poor. Reported herein is our first attempt to refine the stereoselectivity of the cooperatively catalyzed galactosylation reaction. Careful optimization of the reaction conditions along with studying effects of the remote protecting groups led to excellent stereocontrol of α-galactosylation of a variety of glycosyl acceptors with differentially protected galactosyl donors.
- Shadrick, Melanie,Singh, Yashapal,Demchenko, Alexei V.
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p. 15936 - 15944
(2020/11/20)
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- Synthesis of Glycosyl Chlorides and Bromides by Chelation Assisted Activation of Picolinic Esters under Mild Neutral Conditions
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A general method has been developed for the formation of glycosyl chlorides and bromides from picolinic esters under mild and neutral conditions. Benchtop stable picolinic esters are activated by a copper(II) halide species to afford the corresponding products in high yields with a traceless leaving group. Rare β glycosyl chlorides are accessible via this route through neighboring group participation. Additionally, glycosyl chlorides with labile protecting groups previously not easily accessible can be prepared.
- Balzer, Paul G.,Blaszczyk, Stephanie A.,Duan, Xiyan,Ma, Zhi-Xiong,Simmons, Christopher J.,Stevens, Christopher M.,Tang, Weiping,Wang, Hao-Yuan,Wen, Peng,Ye, Wenjing,Yin, Dan
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supporting information
(2020/02/28)
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- Koenigs–Knorr Glycosylation Reaction Catalyzed by Trimethylsilyl Trifluoromethanesulfonate
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The discovery that traditional silver(I)-oxide-promoted glycosidations of glycosyl bromides (Koenigs–Knorr reaction) can be greatly accelerated in the presence of catalytic trimethylsilyl trifluoromethanesulfonate (TMSOTf) is reported. The reaction conditions are very mild that allowed for maintaining a practically neutral pH and, at the same time, providing high rates and excellent glycosylation yields. In addition, unusual reactivity trends among a series of differentially protected glycosyl bromides were documented. In particular, benzoylated α-bromides were much more reactive than their benzylated counterparts under these conditions.
- Singh, Yashapal,Demchenko, Alexei V.
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supporting information
p. 1461 - 1465
(2019/01/04)
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- Regenerative Glycosylation
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Previously, we communicated 3,3-difluoroxindole (HOFox)-mediated glycosylations wherein 3,3-difluoro-3H-indol-2-yl (OFox) imidates were found to be key intermediates. Both the in situ synthesis from the corresponding glycosyl bromides and activation of the OFox imidates could be conducted in a regenerative fashion. Herein, we extend this study to the synthesis of various glycosidic linkages using different sugar series. The main outcome of this study relates to enhanced yields and/or reduced reaction times of glycosylations. The effect of HOFox-mediated reactions is particularly pronounced in case of unreactive glycosyl donors and/or glycosyl acceptors. A multistep regenerative synthesis of oligosaccharides is also reported.
- Singh, Yashapal,Wang, Tinghua,Geringer, Scott A.,Stine, Keith J.,Demchenko, Alexei V.
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p. 374 - 381
(2018/01/01)
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- Pyranoside-into-Furanoside Rearrangement of 4-Pentenyl Glycosides in the Synthesis of a Tetrasaccharide-Related to Galactan I of Klebsiella pneumoniae
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An efficient strategy for synthesis of a spacer-armed tetrasaccharide related to galactan I of Klebsiella pneumoniae is described, which uses newly developed acid-free conditions for the pyranoside-into-furanoside (PIF) rearrangement of a digalactoside bearing a 4-pentenyl group at the anomeric position. The 4-pentenyl aglycon was successfully used both as a leaving group in the glycosylation of 3-(trifluoroacetamido)propanol, and as a temporary anomeric protecting group, allowing conversion into an imidate donor. Regioselective coupling of the disaccharide blocks gave the desired tetrasaccharide sequence required for investigation of the interaction of galactan I with immune-system proteins.
- Verkhnyatskaya, Stella A.,Krylov, Vadim B.,Nifantiev, Nikolay E.
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p. 710 - 718
(2017/02/05)
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- GLYCOMIMETIC INHIBITORS OF PA-IL AND PA-IIL LECTINS
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Compounds, compositions, and methods for the diagnosis and/or treaimeni of medical conditions involving infections with and colonization by Fseudomonas bacteria including, for example, Fseudomonas aeruginosa in the lungs of patients with cystic fibrosis are described.
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Paragraph 0015; 0066
(2018/01/17)
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- Regenerative glycosylation under nucleophilic catalysis
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This article describes 3,3-difluoroxindole (HOFox)-mediated glycosylation. The uniqueness of this approach is that both the in situ synthesis of 3,3-difluoro-3H-indol-2-yl (OFox) glycosyl donors and activation thereof can be conducted in a regenerative fashion as is a typical reaction performed under nucleophilic catalysis. Only a catalytic amount of the OFox imidate donor and a Lewis acid activator are present in the reaction medium. The OFox imidate donor is constantly regenerated upon its consumption until glycosyl acceptor has reacted.
- Nigudkar, Swati S.,Stine, Keith J.,Demchenko, Alexei V.
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supporting information
p. 921 - 923
(2014/02/14)
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- Synthesis of glycosyl fluorides from thio-, seleno-, and telluroglycosides and glycosyl sulfoxides using aminodifluorosulfinium tetrafluoroborates
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Glycosyl fluorides can be synthesized from thio-, seleno-, and telluroglycosides and glycosyl sulfoxides using the aminodifluorosulfinium tetrafluoroborate reagents Xtalfluor-E and -M, with or without added N-bromosuccinimide. Mechanistic studies provide evidence that fluoride is delivered from the tetrafluoroborate counterion.
- Tsegay, Sammi,Williams, Rohan J.,Williams, Spencer J.
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scheme or table
p. 16 - 22
(2012/09/21)
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- New method for regioselective glycosylation employing saccharide oxyanions
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As an alternative concept for glycosylation, the prior activation of acceptor hydroxy groups for selective glycosidic bond formation, was investigated to give complex oligosaccharides. Oxyanions obtained from partially protected saccharides were glycosylated by employing glycopyranosyl halides, and the regiochemical results were studied. Initially, partially methylated methyl-α-D-glucopyranosides were used as a model system to study the underlying mechanistic principles of base-promoted glycosylation. High regioselectivities and stereospecific glycosidic bond formations were achieved, and the scope of the methodology was extended with different perbenzylated glycosyl donors.
- Matwiejuk, Martin,Thiem, Joachim
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experimental part
p. 5860 - 5878
(2011/11/06)
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- Synthesis of α-galactosyl ceramide (KRN7000) and analogues thereof via a common precursor and their preliminary biological assessment
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(Chemical Equation Presented) A new practical synthesis of α-GalCer and of its analogues is presented, opening the chance to easily modify the sphingosine chain. The common precursor is a disaccharide, obtained by coupling tetra-O-benzyl-D-galactose with allyl 2,3-O-isopropylidene-D-lyxofuranoside. Introduction of alkyl chains via Wittig reaction (for α-GalCer and OCH) or via Williamson reaction (for oxa analogues) followed by standard synthetic steps allows one to efficiently obtain such compounds. The analogues are able to activate iNKT cells when presented by CD1d expressing cells.
- Michieletti, Mario,Bracci, Antonio,Compostella, Federica,De Libero, Gennaro,Mori, Lucia,Fallarini, Silvia,Lombardi, Grazia,Panza, Luigi
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body text
p. 9192 - 9195
(2009/04/11)
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- Superarming the S-benzoxazolyl glycosyl donors by simple 2-O-benzoyl-3,4,6-tri-O-benzyl protection
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(Chemical Equation Presented) The strategic placement of common protecting groups led to the discovery of a new method for "superarming" glycosyl donors. Conceptualized from our previous studies on the O-2/O-5 Cooperative Effect, it was determined that S-
- Mydock, Laurel K.,Demchenko, Alexei V.
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supporting information; experimental part
p. 2103 - 2106
(2009/05/27)
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- Glycomimetic inhibitors of the PA-IL lectin, PA-IIL lectin or both the lectins from pseudomonas
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Compositions and methods are provided related to Pseudomonas bacteria. The compositions and methods may be used for diagnosis and therapy of medical conditions involving infection with Pseudomonas bacteria. Such infections include Pseudomonas aeruginosa i
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Page/Page column 10
(2008/06/13)
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- Synthesis and evaluation of human T cell stimulating activity of an α-sulfatide analogue
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A concise synthesis of α-sulfatide 1, an analogue of natural glycolipid antigens with potential anti-tumor activity, was performed. Two different approaches to the α-glycosidic bond were explored, resulting in a high yield and excellent stereoselectivity.
- Franchini, Laura,Matto, Pamela,Ronchetti, Fiamma,Panza, Luigi,Barbieri, Lucia,Costantino, Valeria,Mangoni, Alfonso,Cavallari, Marco,Mori, Lucia,De Libero, Gennaro
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p. 5529 - 5536
(2008/03/13)
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- Efficient stereoselective synthesis of γ-N-glycosyl asparagines by N-glycosylation of primary amide groups
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The efficient and elegant synthesis of N-glycosides by N-glycosylation of asparagine-containing peptides is described. Glycosylation of primary amides with glycosyl N-phenyltrifluoroimidates in the presence of a catalytic amount of TMSOTf in nitromethane
- Tanaka, Hiroshi,Iwata, Yuki,Takahashi, Daisuke,Adachi, Masaatsu,Takahashi, Takashi
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p. 1630 - 1631
(2007/10/03)
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- HEPATITIS C VIRUS INHIBITOR COMPRISING ALPHA-GLYCOSYLCERAMIDE AS THE ACTIVE INGREDIENT
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This invention provides a growth inhibitor of human hepatitis C virus comprising, as an active ingredient, α-glycosylceramide used for patients infected with the aforementioned viruses. This inhibitor of hepatitis C virus comprises, as an active ingredien
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Page/Page column 15
(2010/02/11)
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- An easy access to halide ion-catalytic alpha-glycosylation using carbon tetrabromide and triphenylphosphine as multifunctional reagents.
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The reaction of a 2-O-benzyl-1-hydroxy sugar with CBr4 and Ph3P generates a glycosyl bromide in situ, which is coupled with an acceptor alcohol in the presence of N,N-tetramethylurea to afford an alpha-glycosyl product virtually quantitatively. In a proposed pathway, the reagent combination plays multiple roles such as the generation of a glycosyl donor, the activation of glycosylation, and the dehydration of the reaction system. These roles allow a simple alpha-glycosylation to be performed without special attention to dehydration. Various alpha-glycosyl (D-gluco-, D-galacto- and L-fuco-) products including glycosyl glycerols and cholesterols have been prepared with this method.
- Shingu, Yuko,Nishida, Yoshihiro,Dohi, Hirofumi,Kobayashi, Kazukiyo
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p. 2518 - 2521
(2007/10/03)
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- C(2)-(α-Mannosyl)indole: The pivotal intermediate towards the natural C-Glycopeptides
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Two different approaches were investigated to prepare the unusual modified peptide C(2)-mannosylated indole residue. Direct glycosylation of 2-metallated indoles or 2-trimethylsilylindole derivative by reaction with perbenzylated α-D-mannopyranosyl bromid
- Hassan,Spies,Bredenkamp
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p. 1589 - 1598
(2007/10/03)
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- Synthesis of the Leishmania LPG core heptasaccharyl myo-inositol
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Total synthesis of the core heptasaccharyl myo-inositol, Galp(α1-6)Galp(α1-3)Galf(β1-3)[Glcp(α1-PO4-6)Manp](α1-3)Manp(α1-4)GlcN p(α1-6)Ins-1-PO4, and the corresponding hexasaccharyl myo-inositol, Galp(α1-6)Galp(α1-3)Galf(β1-3)Manp(α1
- Ruda,Lindberg,Garegg,Oscarson,Konradsson
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p. 11067 - 11072
(2007/10/03)
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- Synthesis of a hexasaccharide corresponding to part of the heptose-hexose region of the Salmonella Ra core, and a penta- and a tetra-saccharide that compose parts of this structure
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The synthesis of the hexasaccharide 2-(4-trifluoroacetamidophenyl)ethyl O-α-D-galactopyranosyl-(1->3)-6>>-O-α-D-glucopyranosyl-(1->3)-7)>-O-L-glycero-α-D-manno-heptopyranosyl-(1->3)-L-g
- Oscarson, Stefan,Ritzen, Helena
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- Oligosaccharides from "Standardized Intermediates". Synthesis of a Branched Tetrasaccharide Glycoside Related to the Blood Group B Determinant
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A branched tetrasaccharide glycoside (16) isomeric with the human blood group B determinant (type 1) was synthesized from "building block" derivatives of the component monosaccharides.Initially a 2-O-benzoyl-3,6-di-O-benzyl-4-O-substituted-α-D-galactopyra
- Nashed, Mina A.,Anderson, Laurens
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p. 7282 - 7286
(2007/10/02)
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