5019-25-0Relevant articles and documents
General Strategy for the Synthesis of Rare Sugars via Ru(II)-Catalyzed and Boron-Mediated Selective Epimerization of 1,2- trans-Diols to 1,2- cis-Diols
Li, Xiaolei,Tang, Weiping,Wu, Jicheng
, p. 3727 - 3736 (2022/03/02)
Human glycans are primarily composed of nine common sugar building blocks. On the other hand, several hundred monosaccharides have been discovered in bacteria and most of them are not readily available. The ability to access these rare sugars and the corresponding glycoconjugates can facilitate the studies of various fundamentally important biological processes in bacteria, including interactions between microbiota and the human host. Many rare sugars also exist in a variety of natural products and pharmaceutical reagents with significant biological activities. Although several methods have been developed for the synthesis of rare monosaccharides, most of them involve lengthy steps. Herein, we report an efficient and general strategy that can provide access to rare sugars from commercially available common monosaccharides via a one-step Ru(II)-catalyzed and boron-mediated selective epimerization of 1,2-trans-diols to 1,2-cis-diols. The formation of boronate esters drives the equilibrium toward 1,2-cis-diol products, which can be immediately used for further selective functionalization and glycosylation. The utility of this strategy was demonstrated by the efficient construction of glycoside skeletons in natural products or bioactive compounds.
Structure of the unusual Sinorhizobium fredii HH103 lipopolysaccharide and its role in symbiosis
Di Lorenzo, Flaviana,Speciale, Immacolata,Silipo, Alba,Alías-Villegas, Cynthia,Acosta-Jurado, Sebastián,Rodríguez-Carvajal, Miguel-ángel,Dardanelli, Marta S.,Palmigiano, Angelo,Garozzo, Domenico,Ruiz-Sainz, José-Enrique,Molinaro, Antonio,Vinardell, José-María
, p. 10969 - 10987 (2021/01/07)
Rhizobia are soil bacteria that form important symbiotic associations with legumes, and rhizobial surface polysaccharides, such as K-antigen polysaccharide (KPS) and lipopolysaccharide (LPS), might be important for symbiosis. Previously, we obtained a mutant of Sinorhizobium fredii HH103, rkpA, that does not produce KPS, a homopolysaccharide of a pseudaminic acid derivative, but whose LPS electrophoretic profile was indistinguishable from that of the WT strain. We also previously demonstrated that the HH103 rkpLMNOPQ operon is responsible for 5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-L-glyc-ero-L-manno-nonulosonic acid [Pse5NAc7(3OHBu)] production and is involved in HH103 KPS and LPS biosynthesis and that an HH103 rkpM mutant cannot produce KPS and displays an altered LPS structure. Here, we analyzed the LPS structure of HH103 rkpA, focusing on the carbohydrate portion, and found that it contains a highly heterogeneous lipid A and a peculiar core oligosaccharide composed of an unusually high number of hexuronic acids containing b-configured Pse5NAc7(3OHBu). This pseudaminic acid derivative, in its a-configuration, was the only structural component of the S. fredii HH103 KPS and, to the best of our knowledge, has never been reported from any other rhizobial LPS. We also show that Pse5NAc7(3OHBu) is the complete or partial epitope for a mAb, NB6-228.22, that can recognize the HH103 LPS, but not those of most of the S. fredii strains tested here. We also show that the LPS from HH103 rkpM is identical to that of HH103 rkpA but devoid of any Pse5NAc7(3OHBu) residues. Notably, this rkpM mutant was severely impaired in symbiosis with its host, Macroptilium atropurpureum.
Structural properties of D-mannopyranosyl rings containing O-Acetyl side-chains
Turney, Toby,Zhang, Wenhui,Oliver, Allen G.,Serianni, Anthony S.
, p. 1166 - 1174 (2019/08/13)
The crystal structures of 1,2,3,4,6-penta-O-Acetyl--d-mannopyranose, C16H22O11, and 2,3,4,6-Tetra-O-Acetyl--d-mannopyranosyl-(1.2)-3,4,6-Tri-O-Acetyl--d-mannopyranosyl-( 1.3)-1,2,4,6-Tetra-O-Acetyl--d-mannopyranose, C40H54O27, were determined and compared to those of methyl 2,3,4,6-Tetra-O-Acetyl--d-mannopyranoside, methyl -d-mannopyranoside andmethyl -d-mannopyranosyl-(1.2)--d-mannopyranoside to evaluate the effects of O-Acetylation on bond lengths, bond angles and torsion angles. In general, O-Acetylation exerts little effect on the exo-and endocyclic C-C and endocyclic C-O bond lengths, but the exocyclic C-O bonds involved in O-Acetylation are lengthened by -0.02 A ° . The conformation of the O-Acetyl side-chains is highly conserved, with the carbonyl O atom either eclipsing the H atom attached to a 2-Alcoholic C atom or bisecting the H-C-H bond angle of a 1-Alcoholic C atom. Of the two C-O bonds that determine O-Acetyl side-chain conformation, that involving the alcoholic C atom exhibits greater rotational variability than that involving the carbonyl C atom. These findings are in good agreement with recent solution NMR studies of O-Acetyl side-chain conformations in saccharides. Experimental evidence was also obtained to confirm density functional theory (DFT) predictions of C-O and O-H bond-length behavior in a C-O-H fragment involved in hydrogen bonding.
ACYLATED ACTIVE AGENTS AND METHODS OF THEIR USE FOR THE TREATMENT OF AUTOIMMUNE DISORDERS
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Page/Page column 157; 128, (2019/12/28)
Disclosed herein are acylated active agents (e.g., acylated catechin polyphenols, acylated carotenoids, acylated mesalamines, acylated sugars, acylated shikimic acids, acylated ellagic acid, acylated ellagic acid analogue, and acylated hydroxybenzoic acids), active agent combinations (e.g., with a second agent that is a fatty acid) and methods of their use, e.g., for modulating an autoimmunity marker or for treating an autoimmune disorder.
One-pot oxidation-hydrocyanation sequence coupled to lipase-catalyzed diastereoresolution in the chemoenzymatic synthesis of sugar cyanohydrin esters
Hietanen, Ari,Kanerva, Liisa T.
experimental part, p. 2729 - 2737 (2012/07/13)
A three-step, one-pot synthesis and diastereoresolution sequence is described in anhydrous toluene starting from methyl α-D-2,3,4-tri-O- acetylgalacto- (1a), -manno- (1b) and -glucopyranosides (1c). The reaction sequence, including consecutive transformations through the aldehyde [PhI(OAc)2, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)] and cyanohydrin [basic resin or (R)-oxynitrilase] into the (6R)-cyanohydrin ester (lipase) is shown to proceed in a one-pot cascade, except that the basic resin (when used) should be removed before the addition of the enzymatic acylation reagents. We have shown that the effective transformation of 1a (75 % reaction yield) through labile intermediates gives the stable (6R)-cyanohydrin butanoate (85 % de). Further diastereomeric purification by chromatography is possible, although the product is already of high diastereopurity. (6R)-Cyanohydrin esters are obtained through acylation with Burkholderia cepacia lipase. The (6S)-ester (de 99 %) is produced by Candida rugosa lipase when the sequence is started from 1c whereas the other sugar derivatives are less suited to the reaction with lipase. Copyright
Methyl 1,2-orthoesters as useful glycosyl donors in glycosylation reactions: A comparison with n-pent-4-enyl 1,2-orthoesters
Uriel, Clara,Ventura, Juan,Gomez, Ana M.,Lopez, J. Cristobal,Fraser-Reid, Bert
experimental part, p. 3122 - 3131 (2012/07/13)
Mannopyranose-derived methyl 1,2-orthoacetates (R = Me) and -benzoates (R = Ph) can function as glycosyl donors - upon BF3·Et 2O activation in CH2Cl2 - in glycosylation reactions with monosaccharide acceptors to afford disaccharides in good yields. In the process, glycosylation is preferred to acid-catalyzed rearrangement leading to methyl mannopyranosides. Methyl 1,2-orthoesters can be also used in regioselective glycosylation protocols with monosaccharide diols, in which they display good regioselectivity. Copyright
Unexpected stereocontrolled access to 1α,1′β-disaccharides from methyl 1,2-ortho esters
Uriel, Clara,Ventura, Juan,Gomez, Ana M.,Lopez, J. Cristobal,Fraser-Reid, Bert
experimental part, p. 795 - 800 (2012/03/22)
Mannopyranose-derived methyl 1,2-orthoacetates (R = Me) and 1,2-orthobenzoates (R = Ph) undergo stereoselective formation of 1α,1′β-disaccharides, upon treatment with BF 3?Et2O in CH2Cl2, rather than the expected acid-catalyzed reaction leading to methyl glycosides by way of a rearrangement-glycosylation process of the liberated methanol.
Variations on the SnCl4 and CF3CO2Ag-promoted glycosidation of sugar acetates: a direct, versatile and apparently simple method with either α or β stereocontrol
Xue, Jia Lu,Cecioni, Samy,He, Li,Vidal, Sébastien,Praly, Jean-Pierre
experimental part, p. 1646 - 1653 (2009/12/24)
Glycosidation of sugar peracetates (d-gluco, d-galacto) with SnCl4 and CF3CO2Ag led to either 1,2-cis-, or 1,2-trans-glycosides, depending primarily on the alcohols used. In particular, 1,2-trans-glycosides, expected from acyl-protected glycosyl donors, were formed in high yields with alcohols sharing specific features such as bulkiness, presence of electron-withdrawing groups or polyethoxy motifs. In contrast, simple alcohols afforded ～1:1 mixtures of 2,3,4,6-tetra-O-acetyl, and 3,4,6-tri-O-acetyl 1,2-cis-glycosides due to anomerization and/or acid-catalyzed fragmentation of 1,2-orthoester intermediates. After reacetylation or deacetylation, acetylated or fully deprotected 1,2-cis-glycosides (α-d-gluco, α-d-galacto) were obtained in ～90% yields by a simple and direct method.
Indium trichloride promoted stereoselective synthesis of O-glycosides from trialkyl orthoformates
Mukherjee, Debaraj,Yousuf, Syed Khalid,Taneja, Subhash C.
, p. 4944 - 4948 (2008/09/21)
A novel, highly stereoselective method for O-glycosylation of glycals and glycosylbromides is developed using orthoformates as acceptors in the presence of InCl3 to afford the corresponding O-glycopyranosides in 66-94% yield. Both perbenzyl and peracetyl glycals afford the corresponding 2,3-unsaturated-O-glycosides with high α-selectivity. Stoichiometric amounts of orthoformates are sufficient to bring about this transformation instead of large excesses of alcohols.
Tandem epoxidation-alcoholysis or epoxidation-hydrolysis of glycals catalyzed by titanium(IV) isopropoxide or Venturello's phosphotungstate complex
Levecque, Pieter,Gammon, David W.,Kinfe, Henok Hadgu,Jacobs, Pierre,De Vos, Dirk,Sels, Bert
body text, p. 1557 - 1568 (2009/07/10)
Venturello's phosphotungstate complex and titanium(IV) isopropoxide [Ti(O-i-Pr)4] were successfully used as catalysts for the epoxidation-alcoholysis of glycals using hydrogen peroxide [H2O 2]. Reaction substrates included a range of variously protected glycals and different alcohols were used as solvents. Ti(O-i-Pr)4 was only effective in methanol as solvent, but gave methyl glycosides in high yields and high selectivities. The Venturello complex proved to be a very versatile and efficient catalyst. Apart from epoxidation-alcoholysis in alcoholic solvents it also showed activity in biphasic conditions to allow for glycosylation of long-chain alcohols and was very effective in the stereoselective dihydroxylation of benzylated glucal.
