- A Unified Strategy to Access 2- And 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration
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The selective manipulation of carbohydrate scaffolds is challenging due to the presence of multiple, nearly chemically indistinguishable O-H and C-H bonds. As a result, protecting-group-based synthetic strategies are typically necessary for carbohydrate modification. Here we report a concise semisynthetic strategy to access diverse 2- and 4-deoxygenated carbohydrates without relying on the exhaustive use of protecting groups to achieve site-selective reaction outcomes. Our approach leverages a Mn2+-promoted redox isomerization step, which proceeds via sugar radical intermediates accessed by neutral hydrogen atom abstraction under visible light-mediated photoredox conditions. The resulting deoxyketopyranosides feature chemically distinguishable functional groups and are readily transformed into diverse carbohydrate structures. To showcase the versatility of this method, we report expedient syntheses of the rare sugars l-ristosamine, l-olivose, l-mycarose, and l-digitoxose from commercial l-rhamnose. The findings presented here validate the potential for radical intermediates to facilitate the selective transformation of carbohydrates and showcase the step and efficiency advantages attendant to synthetic strategies that minimize a reliance upon protecting groups.
- Carder, Hayden M.,Suh, Carolyn E.,Wendlandt, Alison E.
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supporting information
p. 13798 - 13805
(2021/09/07)
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- Copper-Catalyzed Anomeric O-Arylation of Carbohydrate Derivatives at Room Temperature
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Direct and practical anomeric O-arylation of sugar lactols with substituted arylboronic acids has been established. Using copper catalysis at room temperature under an air atmosphere, the protocol proved to be general, and a variety of aryl O-glycosides have been prepared in good to excellent yields. Furthermore, this approach was extended successfully to unprotected carbohydrates, including α-mannose, and it was demonstrated here how the interaction between carbohydrates and boronic acids can be combined with copper catalysis to achieve selective anomeric O-arylation.
- Verdelet, Tristan,Benmahdjoub, Sara,Benmerad, Belkacem,Alami, Mouad,Messaoudi, Samir
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p. 9226 - 9238
(2019/08/12)
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- Phenyl glycosides – Solid-state NMR, X-ray diffraction and conformational analysis using genetic algorithm
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The X-ray structures of 2,6-dimethylphenyl and phenyl 2,3,4,6-tetra-O-acetyl β-glucosides (1 and 3) and phenyl α-mannoside (6) were obtained. The independent part of the unit cell of the glycosides 1 and 6 was formed by one molecule, and for the glucoside 3, two molecules in the crystal cell were observed. In deacetylated glycosides 4 and 6 the crystal structure was established by a hydrogen bond network formed between the sugar hydroxyls and solvent molecules. The 13C CPMAS NMR spectra of aryl glycosides 1–6 were analysed. In the spectrum of 3, doubling of the C4 aryl signal was observed which confirmed the presence of two independent molecules in the solid sample. The GAAGS (Genetic Algorithm-Assisted Grid Search) method was used to determine the low-energy conformers of α-mannosides and β-glucosides. The orientation of the aryl pendant group was calculated using Molecular Mechanics (MMFF94) as well as Quantum Mechanics theory (DFT, B3LYP/6-31 + G(d,p)).
- Wa?ejko, Piotr,Bukowicki, Jaros?aw,Dobrzycki, ?ukasz,Socha, Pawe?,Paradowska, Katarzyna
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p. 126 - 136
(2019/01/03)
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- Copper-mediated anomeric: O -arylation with organoboron reagents
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Copper-mediated couplings of arylboroxines with glycosyl hemiacetals furnish O-aryl glycosides via Csp2-O bond formation. The method enables the anomeric O-arylation of protected pyranose and furanose derivatives, and is tolerant of functionalized arylboroxine partners. Whereas mixtures of anomers are formed from glucopyranose, galactopyranose and arabinofuranose hemiacetals, the α-anomer is generated selectively from mannopyranose and mannofuranose-derived substrates.
- Dimakos, Victoria,Liu, Jacklyn J. W.,Ge, Zhenlu,Taylor, Mark S.
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supporting information
p. 5671 - 5674
(2019/06/18)
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- Stereocontrolled Synthesis of Phenolic α-d-Glycopyranosides
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Adopting the ‘remote activation concept’ toward stereocontrolled glycoside synthesis with minimal use of protection groups, a general synthesis of phenolic 1,2-cis glycopyranosides is reported, as exemplified by aryl α-d-galacto-, α-d-gluco- and 2-azido α-d-glucopyranosides among others using glycosyl donors bearing an anomeric (3-bromo-2-pyridyloxy) group and catalyzed by methyl triflate.
- St-Pierre, Gabrielle,Dafik, Laila,Klegraf, Ellen,Hanessian, Stephen
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p. 3575 - 3588
(2016/10/17)
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- Palladium-catalyzed ullmann-type reductive homocoupling of iodoaryl glycosides
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A catalytic synthesis of novel biaryl-linked divalent glycosides was achieved using an electroreductive palladium-catalyzed iodoaryl-iodoaryl coupling reaction. This new method was optimized for the synthesis of divalent biaryl-linked mannopyranosides that was subsequently generalized toward several carbohydrate substrates with yields up to 96%.
- Bergeron-Brlek, Milan,Giguere, Denis,Shiao, Tze Chieh,Saucier, Catherine,Roy, Rene
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scheme or table
p. 2971 - 2977
(2012/05/04)
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- COMPOUNDS AND METHODS FOR TREATING BACTERIAL INFECTIONS
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The present invention encompasses compounds and methods for treating urinary tract infections.
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Page/Page column 69-70
(2011/05/06)
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- Odorless eco-friendly synthesis of thio- and selenoglycosides in ionic liquid
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An environmentally benign odorless methodology for the preparation of 1,2-trans-thio- and selenoglycosides is reported. In a one-pot condition, the reductive cleavage of disulfides and diselenides using triethylsilane and borontrifluoride diethyletherate combination followed by the reaction of the in situ generated thiolate and selenoetes with glycosyl acetate derivatives in recyclable room-temperature ionic liquid, [BMIM]BFresulted in excellent yields of thio- and selenoglycosides avoiding the use of obnoxious thiols/selenols and metallic catalysts.
- Sau, Abhijit,Misra, Anup Kumar
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experimental part
p. 1905 - 1911
(2011/10/08)
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- Synthesis of glycocinnasperimicin D
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The first total synthesis of amino sugar antibiotic glycocinnasperimicin D (1) has been achieved by a convergent, three-component coupling strategy. The key steps involve the Heck-Mizoroki reaction by using the iodophenyl glycoside 50 and acryl amide 32 to furnish the right core structure of 1, and the construction of the urea glycoside employing the reaction of glycosyl isocyanate 8 with amino sugar 9. Glycosyl isocyanate 8 was prepared by the oxidation of isonitrile 10, which displayed excellent reactivity in the coupling event. Synthetic roadblocks, encountered during this synthetic effort, have led to the development of the α-selective, Lewis acid catalyzed phenyl glycosylation process with 2-amino-hexopyranose and a procedure for acetonide deprotection without affecting the silyl ethers.
- Nishiyama, Taihei,Kusumoto, Yoshifumi,Okumura, Ken,Hara, Kanako,Kusaba, Shohei,Hirata, Keiko,Kamiya, Yukihiro,Isobe, Minoru,Nakano, Keiji,Kotsuki, Hiyoshizo,Ichikawa, Yoshiyasu
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supporting information; experimental part
p. 600 - 610
(2010/05/02)
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- Iodine-hexamethyldisilane (HMDS)-mediated anomerization of peracetylated 1,2-trans-linked alkyl and aryl glycosides
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Treatment of peracetylated alkyl and aryl 1,2-trans-glycosides with iodine in the presence of HMDS has been found to result in the anomerization leading to the formation of the respective 1,2-cis-glycosides. In the case of alkyl glycosides with aglycons of short alkyl chain length complete anomerization to the α-glycosides was observed while with those of longer chain length the process was found to be incomplete. The observations have been interpreted mechanistically.
- Malik, Satish,Shah, Krupesh J.,Ravindranathan Kartha
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scheme or table
p. 867 - 871
(2010/06/14)
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- Glycocinnasperimicin D Synthetic Studies: Synthesis of Cinnamoyl Glycosides via Iodination-Heck Reaction Sequence Starting from Phenyl Glycosides
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A new approach for the synthesis of cinnamoyl glycoside has been developed via iodination-Heck reaction sequence starting from phenyl glycoside. Successful application of this procedure accomplished the construction of the right core structure of aminosug
- Nishiyama, Taihei,Ichikawa, Yoshiyasu,Isobe, Minoru
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- The catalytic synthesis of aryl O-glycosides using triaryloxyboranes
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Triaryloxyboranes worked as highly reactive glycosyl acceptors of glycosyl acetates to afford aryl O-glycosides in excellent yields. A catalytic amount of ytterbium(III) trifluoromethanesulfonate activated the formation reaction of aryl O-glycosidic linka
- Yamanoi, Takashi,Yamazaki, Ippo
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p. 4009 - 4011
(2007/10/03)
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- Stannic chloride promoted synthesis of mannosides
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Use of anhyd.SnCl4 has been described for the synthesis of aryl, arylalkyl and alkyl α-D-mannopyranosides.A possible mechanism for the formation of α-anomer in these reactions is discussed.
- Irani, Rustom K,Sinha, Bharati,Bose, J L
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p. 519 - 521
(2007/10/02)
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- Synthesis of Levoglucosenone
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Levoglucosenone was synthesized from D-galactose via reductive decarboxylation as a key reaction.Among the catalysts used for the key reaction, hydrous zirconium oxide was found to have the best activity.
- Shibagaki, Makoto,Takahashi, Kyoko,Kuno, Hideyuki,Honda, Ichiro,Matsushita, Hajime
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p. 306 - 310
(2007/10/02)
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- Anhydrous Cupric Sulphate-catalysed Synthesis of Glycosides
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Anhydrous CuSO4 has been successfully used as a catalyst for the glycosidation of phenols and alcohols using fully acetylated sugars.In this reaction, formation of the anomeric glycosides without concomitant anomerisation implies the involvement of a carbonium oxonium ion hybrid derived from the fully acetylated sugar.
- Sinha, Bharati,Pansare, V. S.
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p. 825 - 826
(2007/10/02)
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