2872-72-2Relevant articles and documents
A Unified Strategy to Access 2- And 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration
Carder, Hayden M.,Suh, Carolyn E.,Wendlandt, Alison E.
supporting information, p. 13798 - 13805 (2021/09/07)
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.
Copper-Catalyzed Anomeric O-Arylation of Carbohydrate Derivatives at Room Temperature
Verdelet, Tristan,Benmahdjoub, Sara,Benmerad, Belkacem,Alami, Mouad,Messaoudi, Samir
, p. 9226 - 9238 (2019/08/12)
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.
Copper-mediated anomeric: O -arylation with organoboron reagents
Dimakos, Victoria,Liu, Jacklyn J. W.,Ge, Zhenlu,Taylor, Mark S.
supporting information, p. 5671 - 5674 (2019/06/18)
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.
Phenyl glycosides – Solid-state NMR, X-ray diffraction and conformational analysis using genetic algorithm
Wa?ejko, Piotr,Bukowicki, Jaros?aw,Dobrzycki, ?ukasz,Socha, Pawe?,Paradowska, Katarzyna
, p. 126 - 136 (2019/01/03)
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)).
Structure-based discovery of glycomimetic FmlH ligands as inhibitors of bacterial adhesion during urinary tract infection
Kalas, Vasilios,Hibbing, Michael E.,Maddirala, Amarendar Reddy,Chugani, Ryan,Pinkner, Jerome S.,Mydock-McGrane, Laurel K.,Conover, Matt S.,Janetka, James W.,Hultgren, Scott J.
, p. E2819 - E2828 (2018/03/27)
Treatment of bacterial infections is becoming a serious clinical challenge due to the global dissemination of multidrug antibiotic resistance, necessitating the search for alternative treatments to disarm the virulence mechanisms underlying these infections. Uropathogenic Escherichia coli (UPEC) employs multiple chaperone- usher pathway pili tipped with adhesins with diverse receptor specificities to colonize various host tissues and habitats. For example, UPEC F9 pili specifically bind galactose or N-acetylgalactosamine epitopes on the kidney and inflamed bladder. Using X-ray structureguided methods, virtual screening, and multiplex ELISA arrays, we rationally designed aryl galactosides and N-acetylgalactosaminosides that inhibit the F9 pilus adhesin FmlH. The lead compound, 29β-NAc, is a biphenyl N-acetyl-β-galactosaminoside with a Ki of ～90 nM, representing a major advancement in potency relative to the characteristically weak nature of most carbohydrate-lectin interactions. 29β-NAc binds tightly to FmlH by engaging the residues Y46 through edge-to-face π-stacking with its A-phenyl ring, R142 in a salt-bridge interaction with its carboxylate group, and K132 through watermediated hydrogen bonding with its N-acetyl group. Administration of 29β-NAc in a mouse urinary tract infection (UTI) model significantly reduced bladder and kidney bacterial burdens, and coadministration of 29β-NAc and mannoside 4Z269, which targets the type 1 pilus adhesin FimH, resulted in greater elimination of bacteria from the urinary tract than either compound alone. Moreover, FmlH specifically binds healthy human kidney tissue in a 29β-NAc-inhibitable manner, suggesting a key role for F9 pili in human kidney colonization. Thus, these glycoside antagonists of FmlH represent a rational antivirulence strategy for UPEC-mediated UTI treatment.
Stereocontrolled Synthesis of Phenolic α-d-Glycopyranosides
St-Pierre, Gabrielle,Dafik, Laila,Klegraf, Ellen,Hanessian, Stephen
, p. 3575 - 3588 (2016/10/17)
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.
Palladium-catalyzed ullmann-type reductive homocoupling of iodoaryl glycosides
Bergeron-Brlek, Milan,Giguere, Denis,Shiao, Tze Chieh,Saucier, Catherine,Roy, Rene
scheme or table, p. 2971 - 2977 (2012/05/04)
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%.
Application of silver N-heterocyclic carbene complexes in O-glycosidation reactions
Talisman, Ian J.,Kumar, Vineet,Deschamps, Jeffrey R.,Frisch, Mark,Malhotra, Sanjay V.
experimental part, p. 2337 - 2341 (2011/12/04)
We report the efficient O-glycosidation of glycosyl bromides with therapeutically relevant acceptors facilitated by silver N-heterocyclic carbene (Ag-NHC) complexes. A set of four Ag-NHC complexes was synthesized and evaluated as promoters for glycosidation reactions. Two new bis-Ag-NHC complexes derived from ionic liquids 1-benzyl-3-methyl-1H-imidazolium chloride and 1-(2-methoxyethyl)-3-methylimidazolium chloride were found to efficiently promote glycosidation, whereas known mono-Ag complexes of 1,3-bis(2,4,6- trimethylphenyl)imidazolium chloride and 1,3-bis(2,6-di-isopropylphenyl) imidazolium chloride failed to facilitate the reaction. The structures of the promoters were established by X-ray crystallography and these complexes were employed in the glycosidation of different glycosyl bromide donors with biologically valuable acceptors, such as estrone, estradiol, and various flavones. The products were obtained in yields considered good to excellent, and all reactions were highly selective for the β isomer regardless of neighboring group effects.
O-Glycosidation reactions promoted by in situ generated silver N-heterocyclic carbenes in ionic liquids
Talisman, Ian Jamie,Kumar, Vineet,Razzaghy, Jacqueline,Malhotra, Sanjay V.
experimental part, p. 883 - 890 (2011/06/20)
We herein report O-glycosidation reactions promoted via silver N-heterocyclic carbene complexes formed in situ in ionic liquids. Seven different room temperature ionic liquids were screened for the glycosidation reaction of 4-nitrophenol with tetra-O-acetyl-α-d-galactopyranosyl bromide. Good to excellent yields were obtained using Ag-NHC complexes derived from imidazolium halide salts to promote the glycosidation reaction, whereas yields considered moderate to low were obtained without use of the silver carbene complex. Anion metathesis of the ionic liquids with inexpensive alkylammonium halides also resulted in silver N-heterocyclic carbene formation and subsequent O-glycosidation in the presence of silver carbonate. Effective utility of this methodology has been demonstrated with biologically relevant acceptors (including flavones and steroids) where O-β-glycoside products were obtained selectively in moderate to good yields. We have also demonstrated that the Ag-NHC complex is a superior promoter to traditionally used silver carbonate for the glycosidation of polyphenolic acceptors. The ionic liquids used in the study could be recycled three times without apparent loss in activity.
Copper(II) triflate: A versatile catalyst for the one-pot preparation of orthogonally protected glycosides
Tran, Anh-Tuan,Jones, Rachel A.,Pastor, Julien,Boisson, Julien,Smith, Nichola,Galan, M. Carmen
, p. 2593 - 2598 (2011/12/04)
The development of general and expedient methodologies for the preparation of orthogonally protected glycoside building blocks is essential for the efficient synthesis of complex oligosaccharides. Herein, we describe a new approach that uses copper(II) triflate as a versatile catalyst for the one-pot preparation of orthogonal protected thio- and O-glycosides from the corresponding unprotected counterparts. The conditions are mild, easy to handle and applicable to two and three one-pot tandem transformations, which include arylidene acetalation, esterification, regioselective reductive acetal ring opening, glycosylation and silylation processes. Copyright
