The Experts below are selected from a list of 447 Experts worldwide ranked by ideXlab platform
Xiangming Zhu - One of the best experts on this subject based on the ideXlab platform.
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thioperoxide mediated activation of thioglycoside donors
Organic Letters, 2014Co-Authors: Xiangming ZhuAbstract:Thioperoxide (1) in combination with trimethylsilyl trifluoromethanesulfonate (TMSOTf) provides a powerful thiophilic promoter system, capable of activating different thioglycosides. Both armed and disarmed thioglycosides were activated effectively in the presence of different glycosyl acceptors, giving glycosidation products in high to excellent yields. A plausible activation pathway was also proposed and supported by isolating side-products trifluoromethylphenyl disulfide (CF3SSPh) and alkene (42).
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Thioperoxide-Mediated Activation of Thioglycoside Donors
2014Co-Authors: Xiangming ZhuAbstract:Thioperoxide (1) in combination with trimethylsilyl trifluoromethanesulfonate (TMSOTf) provides a powerful thiophilic promoter system, capable of activating different thioglycosides. Both armed and disarmed thioglycosides were activated effectively in the presence of different glycosyl acceptors, giving glycosidation products in high to excellent yields. A plausible activation pathway was also proposed and supported by isolating side-products trifluoromethylphenyl disulfide (CF3SSPh) and alkene (42)
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synthesis of thioglycoside analogues of maradolipid
Journal of Organic Chemistry, 2013Co-Authors: Xiaojun Zeng, Xiangming Zhu, Raymond SmithAbstract:We describe here the first synthesis of thioglycoside analogues of maradolipid, based on a new procedure for the synthesis of 1-thiotrehalose developed recently in our laboratories. The challenging α,α-(1→1') thioglycosidic linkage was constructed by Schmidt's inverse procedure in very high yield and excellent stereoselectivity. Subsequent protecting group manipulation and coupling with different fatty acids led smoothly to a group of symmetrical and unsymmetrical thiomaradolipids which would be of high value for biological studies.
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The first synthesis of a thioglycoside analogue of the immunostimulant KRN7000.
Organic letters, 2008Co-Authors: Ravindra T Dere, Xiangming ZhuAbstract:The first total synthesis of a thioglycoside analogue of KRN7000, a potential immunostimulant, is described. Two key intermediates are α-galactosyl thiol 4 and phytosphingosine derivative 5, which were both prepared from d-galactose.
Robert A Field - One of the best experts on this subject based on the ideXlab platform.
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convergent synthesis of a trisaccharide as its 2 trimethylsilyl ethyl glycoside related to the flavonoid triglycoside from gymnema sylvestre
Carbohydrate Research, 2006Co-Authors: Robert A FieldAbstract:The glycone part of the flavonoid triglycoside, kaempferol 3-O-β-d-glucopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside, has been synthesized in good yield and stereoselectivity using N-iodosuccinimide and HClO4–silica promoted glycosylations of thioglycoside donors.
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convergent synthesis of a trisaccharide as its 2 trimethylsilyl ethyl glycoside related to the flavonoid triglycoside from gymnema sylvestre
Carbohydrate Research, 2006Co-Authors: Robert A FieldAbstract:The glycone part of the flavonoid triglycoside, kaempferol 3-O-beta-D-glucopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-galactopyranoside, has been synthesized in good yield and stereoselectivity using N-iodosuccinimide and HClO4-silica promoted glycosylations of thioglycoside donors.
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the hydrophobic mannoside manα1 6manα1 s ch2 7 ch3 acts as an acceptor for the udp gal glycosylphosphatidylinositol anchor α1 3 galactosyltransferase of trypanosoma brucei
Biochemical Journal, 1995Co-Authors: Sabine Pingel, Robert A Field, Maria Lucia S Guther, Michael DuszenkoAbstract:The variant surface glycoproteins (VSGs) of Trypanosoma brucei are attached to the plasma membrane via a glycosylphosphatidylinositol (GPI) membrane anchor. This anchor contains the core sequence ethanolamine-PO4-6Man alpha 1-2Man alpha 1-6Man alpha 1-4GlcN alpha 1-6myo-inositol, which is conserved in all GPI anchors, and a unique alpha Gal side chain attached to the 3-position of the alpha Man residue adjacent to the alpha GlcN residue. Here we report that trypanosome membranes can catalyse the transfer of Gal from UDP-Gal to the hydrophobic thioglycoside Man alpha 1-6Man alpha 1-S-(CH2)7-CH3. Characterization of the galactosylated products by electrospray mass spectrometry, exoglycosidase digestion and periodate-oxidation studies revealed that the major product was Man alpha 1-6(Gal alpha 1-3)Man alpha 1-S-(CH2)7-CH3. The similarity of this product to part of the mature VSG GPI anchor suggests that the thioglycoside is able to act as an acceptor for the trypanosome-specific UDP-Gal-GPI anchor alpha 1,3-galactosyltransferase.
John M Gardiner - One of the best experts on this subject based on the ideXlab platform.
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synthesis of l iduronic acid derivatives via 3 2 1 and 2 2 2 l iduronic lactones from bulk glucose derived cyanohydrin hydrolysis a reversible conformationally switched superdisarmed rearmed lactone route to heparin disaccharides
Journal of Organic Chemistry, 2015Co-Authors: Steen U Hansen, Charlotte E Dalton, Marek Barath, Glenn Kwan, James Raftery, Gordon C Jayson, Gavin J Miller, John M GardinerAbstract:l-Idofuranoside cyanohydrin 1 is converted on large scale into a mixture of l-IdoA methyl pyranosides and furanosides, which is converged to provide short 2-step routes to bicyclic [3.2.1] or [2.2.2] l-iduronate lactones. The former is obtained via a 100 g scale synthesis of 3-OBn l-IdoA. A two-step conversion of this mixture provides either pure anomer of the novel [2.2.2] l-iduronate thioglycoside lactones. Both [3.2.1] and [2.2.2] lactones are converted into GlcN-IdoA heparin precursor disaccharides. The [2.2.2] lactone enables a scalable 3-step route from 1 to a new type of highly disarmed O-4 iduronate thioglycoside, which is an effective acceptor with glucoazide thioglycoside donors. The resulting new iduronic [2.2.2] lactone disaccharides are readily rearmed by mild methanolysis to provide GlcN-IdoA thiophenyl disaccharide donors, intercepting their established utility for the assembly of both heparin- and heparan sulfate-like oligosaccharides. The [2.2.2] lactonization acts as a conformational switch to superdisarm iduronate components, reversible by lactone ring opening. In addition, the separated 2,4-diacetates also provide short access to all four anomeric and ring size isomers of l-iduronic acid methyl glycosides, including the first syntheses of the parent idofuranosides. X-ray structures are reported for a [2.2.2] iduronate lactone and examples of both methyl l-idopyranoside and novel methyl-l-idofuranoside systems.
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Synthesis of l‑Iduronic Acid Derivatives via [3.2.1] and [2.2.2] l‑Iduronic Lactones from Bulk Glucose-Derived Cyanohydrin Hydrolysis: A Reversible Conformationally Switched Superdisarmed/Rearmed Lactone Route to Heparin Disaccharides
2015Co-Authors: Steen U. Hansen, Charlotte E Dalton, Glenn Kwan, James Raftery, Gordon C Jayson, Gavin J Miller, Marek Baráth, John M GardinerAbstract:l-Idofuranoside cyanohydrin 1 is converted on large scale into a mixture of l-IdoA methyl pyranosides and furanosides, which is converged to provide short 2-step routes to bicyclic [3.2.1] or [2.2.2] l-iduronate lactones. The former is obtained via a 100 g scale synthesis of 3-OBn l-IdoA. A two-step conversion of this mixture provides either pure anomer of the novel [2.2.2] l-iduronate thioglycoside lactones. Both [3.2.1] and [2.2.2] lactones are converted into GlcN-IdoA heparin precursor disaccharides. The [2.2.2] lactone enables a scalable 3-step route from 1 to a new type of highly disarmed O-4 iduronate thioglycoside, which is an effective acceptor with glucoazide thioglycoside donors. The resulting new iduronic [2.2.2] lactone disaccharides are readily rearmed by mild methanolysis to provide GlcN-IdoA thiophenyl disaccharide donors, intercepting their established utility for the assembly of both heparin- and heparan sulfate-like oligosaccharides. The [2.2.2] lactonization acts as a conformational switch to superdisarm iduronate components, reversible by lactone ring opening. In addition, the separated 2,4-diacetates also provide short access to all four anomeric and ring size isomers of l-iduronic acid methyl glycosides, including the first syntheses of the parent idofuranosides. X-ray structures are reported for a [2.2.2] iduronate lactone and examples of both methyl l-idopyranoside and novel methyl-l-idofuranoside systems
Suvarn S Kulkarni - One of the best experts on this subject based on the ideXlab platform.
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total synthesis of the lipid anchor attached core trisaccharides of lipoteichoic acids of streptococcus pneumoniae and streptococcus oralis uo5
Organic Letters, 2020Co-Authors: Balasaheb K Ghotekar, Ananda Rao Podilapu, Suvarn S KulkarniAbstract:Herein we report an efficient total synthesis of lipid-anchor-appended core trisaccharides of lipoteichoic acids of Streptococcus pneumoniae and Streptococcus oralis Uo5. The key features include the expedient synthesis of the rare sugar 2,4,6-trideoxy-2-acetamido-4-amino-d-Galp building block via one-pot sequential SN2 reactions and the α-selective coupling of d-Thioglucoside with the diacyl glycerol acceptor to construct a common disaccharide acceptor, which was utilized in the total synthesis of target molecules 1 and 2.
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From l-Rhamnose to Rare 6-Deoxy-l-Hexoses
Organic letters, 2016Co-Authors: Someswara Rao Sanapala, Suvarn S KulkarniAbstract:Efficient and rapid transformation of cheaply available l-rhamnose into all the isomeric 6-deoxy-l-hexoses via regio- and stereoselective nucleophilic displacements of triflates is reported. The synthesis entails regioselective protections, one-pot double displacements of triflates, and cascade inversions. The methodology allows facile access to all the rare 6-deoxy-l-hexoses as stable thioglycoside building blocks.
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From l‑Rhamnose to Rare 6‑Deoxy‑l‑Hexoses
2016Co-Authors: Someswara Rao Sanapala, Suvarn S KulkarniAbstract:Efficient and rapid transformation of cheaply available l-rhamnose into all the isomeric 6-deoxy-l-hexoses via regio- and stereoselective nucleophilic displacements of triflates is reported. The synthesis entails regioselective protections, one-pot double displacements of triflates, and cascade inversions. The methodology allows facile access to all the rare 6-deoxy-l-hexoses as stable thioglycoside building blocks
Jinq-chyi Lee - One of the best experts on this subject based on the ideXlab platform.
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N-Iodosuccinimide and acid-washed molecular sieves (NIS/AW-300 MS) as promoters in thioglycoside activation
Tetrahedron, 2014Co-Authors: Chun-hsu Yao, Jinq-chyi LeeAbstract:Abstract The development of an alternative promoter system for thioglycoside activation comprising N -iodosuccinimide (NIS) and acid-washed molecular sieves (AW-300 MS) has been studied and found to mediate high-yielding coupling with a variety of glycosyl acceptors. The utility of this combination is further exemplified by its application to reactivity-based coupling of thioglycosides and sequential one-pot regioselective glycosylation.
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n iodosuccinimide and acid washed molecular sieves nis aw 300 ms as promoters in thioglycoside activation
Tetrahedron, 2014Co-Authors: Chun-hsu Yao, Jinq-chyi LeeAbstract:Abstract The development of an alternative promoter system for thioglycoside activation comprising N-iodosuccinimide (NIS) and acid-washed molecular sieves (AW-300 MS) has been studied and found to mediate high-yielding coupling with a variety of glycosyl acceptors. The utility of this combination is further exemplified by its application to reactivity-based coupling of thioglycosides and sequential one-pot regioselective glycosylation.
