Synthesis and structure of tricarbonyl(η⁶-arene)chromium complexes of phenyl and benzyl D-glycopyranosides

• Thomas Ziegler and
• Ulrich Heber

Beilstein J. Org. Chem. 2012, 8, 1059–1070, doi:10.3762/bjoc.8.118

• Thomas Ziegler Ulrich Heber Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076 Tuebingen, Germany 10.3762/bjoc.8.118 Abstract A series of 15 glycoside-derived tricarbonyl(η6-arene)chromium complexes were prepared in 19–87% yield by heating fully acetylated or

• prevent the excessive sublimation of Cr(CO)6 during the formation of the arene–chromium complexes [17]. Therefore, we used method (b) for the preparation of tricarbonyl(η6-arene)chromium complexes of glycosides as follows. One equivalent of phenyl or benzyl glycoside 1 and one equivalent of Cr(CO)6 were

• sample with iodine in CHCl3 followed by measurement of the NMR spectrum of the formed glycoside. The latter showed a CH-coupling constant at the anomeric center of 173.9 Hz, which is indicative of an α-anomer [19]. As additional proof for the anomeric configuration of 2f, we also prepared β-anomer 2g

Low-generation dendrimers with a calixarene core and based on a chiral C₂-symmetric pyrrolidine as iminosugar mimics

• Marco Marradi,
• Stefano Cicchi,
• Francesco Sansone,
• Alessandro Casnati and
• Andrea Goti

Beilstein J. Org. Chem. 2012, 8, 951–957, doi:10.3762/bjoc.8.107

• [14]. Multivalent calixarenes functionalised with carbohydrate units (glycocalixarenes) [15] have been extensively reported in the literature and represent examples of sugar clustering on macrocyclic structures [16][17]. Thanks to the “glycoside cluster effect” [18][19][20], glycocalixarenes can

• enhance the avidity of interactions between glycans and lectins [15]. Some glycocalixarenes have shown remarkable inhibition properties towards galectins [21][22] or Pseudomonas Aeruginosa lectin [23], the inhibition ability being dependent on the macrocyclic conformation and presentation of the glycoside

• units. With the purpose of expanding the valency and increasing the glycoside density, glycodendrimers have also been synthesised and their properties in protein–carbohydrate interactions have been studied [24][25][26]. However, the innovative frontier of combining glycodendrimeric arrangements onto a

The use of glycoinformatics in glycochemistry

• Thomas Lütteke

Beilstein J. Org. Chem. 2012, 8, 915–929, doi:10.3762/bjoc.8.104

• glycan chain, and by glycoside hydrolases (GH) that remove specific monosaccharides [3]. For this reason there is no technique available to amplify carbohydrates comparable to Polymerase Chain Reaction (PCR) or protein expression systems. Instead, carbohydrates have to be analyzed in physiological

• the enzymes that build or degrade the glycan chains in vivo, the glycosyltransferases or glycoside hydrolases, respectively [46][47][48][49]. To plan such experiments, however, detailed knowledge of the substrate-specificity of these enzymes is required. The same applies to glycan-binding proteins

• (glycosyltransferases, glycoside hydrolases, polysaccharide lyases and carbohydrate esterases) as well as proteins that feature carbohydrate-binding modules is CAZy (Carbohydrate Active Enzymes). This database classifies proteins by sequence comparison and clusters them into families by using well-established

High-affinity multivalent wheat germ agglutinin ligands by one-pot click reaction

• Henning S. G. Beckmann,
• Heiko M. Möller and
• Valentin Wittmann

Beilstein J. Org. Chem. 2012, 8, 819–826, doi:10.3762/bjoc.8.91

• ligands for the Shiga-like [14][15] and cholera toxins [16][17] both belonging to the AB5 family of bacterial toxins. The frequent observation that the binding affinity of a multivalent ligand increases exponentially with the number of binding sites has been termed the glycoside cluster effect [18][19

• ligands. In this report, we describe the preparation of such a series of multivalent WGA ligands by a one-pot procedure for diazo transfer and azide–alkyne cycloaddition [48] starting from commercially available di- and triamines and the propargyl glycoside of N,N’-diacetylchitobiose. Binding potencies

• provoked without any workup procedure by the addition of tris(benzyltriazolylmethyl)amine [55] (TBTA), sodium ascorbate, and the propargyl glycoside 1 [56] of N,N’-diacetylchitobiose and heating of the mixture to 80 °C by microwave irradiation, until TLC showed complete consumption of the intermediate

Formation of carbohydrate-functionalised polystyrene and glass slides and their analysis by MALDI-TOF MS

• Martin J. Weissenborn,
• Johannes W. Wehner,
• Christopher J. Gray,
• Robert Šardzík,
• Claire E. Eyers,
• Thisbe K. Lindhorst and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2012, 8, 753–762, doi:10.3762/bjoc.8.86

• be useful in a bacterial adhesion inhibition assay against the bacterial lectin FimH [20][21]. The second glycoside 7 has been used previously for well-established enzymatic surface modifications [22]. Both these compounds can be synthesised by starting from commercially available 11

Synthesis and antiviral activities of spacer-linked 1-thioglucuronide analogues of glycyrrhizin

• Christian Stanetty,
• Andrea Wolkerstorfer,
• Hassan Amer,
• Andreas Hofinger,
• Ulrich Jordis,
• Dirk Claßen-Houben and
• Paul Kosma

Beilstein J. Org. Chem. 2012, 8, 705–711, doi:10.3762/bjoc.8.79

• the diphenylmethyl ester of glycyrrhetinic acid 7 [19] was then used for the introduction of the spacer-extended 1-thio-glucopyranosiduronate residue. Coupling of the 3β-amino derivative 7 with two equivalents of the 2-iodoethyl glycoside 6 in DMF in the presence of Hünig base proceeded smoothly to

• exhibited no toxicity at concentrations up to 250 μM and significantly enhanced the anti-influenza virus activity of the natural triterpene glycoside glycyrrhizin. Structure of glycyrrhizin (GL), carbenoxolone (CBX), and spacer analogues. 400 MHz 1H NMR expansion plots of the carbohydrate region of compound

Sonogashira–Hagihara reactions of halogenated glycals

• Dennis C. Koester and
• Daniel B. Werz

Beilstein J. Org. Chem. 2012, 8, 675–682, doi:10.3762/bjoc.8.75

• monosaccharide, this approach is unique due to its use of fully functionalized sugars, thus avoiding further refunctionalization steps to obtain the native C-glycoside. Results and Discussion Despite the numerous organometallic reactions performed with substituted glycals, to the best of our knowledge there has

• SN2-type reaction takes place leading to the α-gluco-configured C-glycoside 15a in a moderate yield of 30% (Table 4). The aluminium centre coordinates the epoxide oxygen allowing the hydride to attack from the same side, leading to β-configured alkyl-C-glycosides. The epoxidation/ring-opening sequence

An easy α-glycosylation methodology for the synthesis and stereochemistry of mycoplasma α-glycolipid antigens

• Yoshihiro Nishida,
• Yuko Shingu,
• Yuan Mengfei,
• Kazuo Fukuda,
• Hirofumi Dohi,
• Sachie Matsuda and
• Kazuhiro Matsuda

Beilstein J. Org. Chem. 2012, 8, 629–639, doi:10.3762/bjoc.8.70

• asymmetric glycerol moiety. Results and Discussion A practical synthetic access to GGPL-I homologues GGPL-I provides two key asymmetric centers to be controlled, literally, in the synthetic pathway. One is the configuration at the chiral glycerol moiety, and another is the sugar α-glycoside linkage. In

2-Allylphenyl glycosides as complementary building blocks for oligosaccharide and glycoconjugate synthesis

• Hemali D. Premathilake and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2012, 8, 597–605, doi:10.3762/bjoc.8.66

• ]. Additionally, 4-pentenol is rather expensive ($ 323/50 g, Aldrich), and although O-pentenyl can be introduced from the anomeric acetate directly, the most economical synthesis includes a three-step protocol, with halide, orthoester, and the rearrangement of the latter to glycoside. Results and Discussion As a

Electrochemical generation of 2,3-oxazolidinone glycosyl triflates as an intermediate for stereoselective glycosylation

• Toshiki Nokami,
• Akito Shibuya,
• Yoshihiro Saigusa,
• Shino Manabe,
• Yukishige Ito and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2012, 8, 456–460, doi:10.3762/bjoc.8.52

• limitations of the glycosylation reaction using electrochemically generated glycosyl triflates are in progress in our laboratory. 1H NMR spectrum of glycosyl triflate 2a. Electrochemical conversion of thioglycosides to glycosyl triflates. Triflic acid mediated isomerization of β-glycoside. 1H- and 13C NMR

Facile synthesis of nitrophenyl 2-acetamido-2-deoxy-α-D-mannopyranosides from ManNAc-oxazoline

• Karel Křenek,
• Petr Šimon,
• Lenka Weignerová,
• Barbora Fliedrová,
• Marek Kuzma and
• Vladimír Křen

Beilstein J. Org. Chem. 2012, 8, 428–432, doi:10.3762/bjoc.8.48

• solvent (CH2Cl2, THF, toluene, benzene), all of which were not successful. Finally, we found that trimethylsilyl trifluoromethanesulfonate in dichloromethane [11] was capable of catalyzing the oxazoline ring opening with phenol to afford α-phenyl glycoside 4 in a reasonable 56% yield. This reaction was

• also tested with p-nitrophenol; however, the required p-nitrophenyl glycoside 6 was produced under these conditions only in trace amounts (observed by TLC). Our and previously published results [11] indicate that the deactivation of phenol by the electron-withdrawing nitro group substantially decreases

• its reactivity in the glycosylation reaction with oxazoline and, on the other hand, the presence of electron-donating groups increases the yields. The resulting phenyl glycoside 4 was treated with a solution of red fuming nitric acid in acetic acid [16], producing a mixture of o-nitrophenyl glycoside

Synthesis of heteroglycoclusters by using orthogonal chemoselective ligations

• Baptiste Thomas,
• Michele Fiore,
• Isabelle Bossu,
• Pascal Dumy and
• Olivier Renaudet

Beilstein J. Org. Chem. 2012, 8, 421–427, doi:10.3762/bjoc.8.47

• viruses or bacteria [2][3][4][5]. In a suitable density and spatial display, clusters of carbohydrate indeed allow multiple contacts with a target protein, thus increasing avidity by means of the “glycoside cluster effect” [6][7]. While the recent progress in glycomics has led to the design of

Dependency of the regio- and stereoselectivity of intramolecular, ring-closing glycosylations upon the ring size

• Patrick Claude,
• Christian Lehmann and
• Thomas Ziegler

Beilstein J. Org. Chem. 2011, 7, 1609–1619, doi:10.3762/bjoc.7.189

• leaving group [5][6][7][8][9]. In the “aglycon-delivery concept”, the glycosyl acceptor is attached to a labile acetal [10][11][12][13][14] or silylene group [15][16][17], which is cleaved and the glycosyl acceptor is “delivered” to the anomeric center upon its activation. In the “prearranged-glycoside

• intramolecular, ring-closing condensation occurs affording a tethered saccharide (Figure 1). Despite the fact that the “prearranged-glycoside concept” for intramolecular glycosylation has been successfully applied to the construction of glycosidic bonds that are otherwise difficult to establish (i.e., β-D

• the prearranged glycoside 5a, only the β(1→3)-linked product 6a (50%) and the α(1→3)-linked product 7a (6%) were obtained upon intramolecular glycosylation, forming an 18-membered macrocyclic ring. No (1→2)-linked disaccharides 8 were detected. The structures of 6a and 7a were unambiguously assigned

Convergent synthesis of the tetrasaccharide repeating unit of the O-antigen of Shigella boydii type 9

• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2011, 7, 1182–1188, doi:10.3762/bjoc.7.137

• glycoside in high yield. Keywords: diarrhea; glycosylation; O-antigen; oligosaccharide; Shigella boydii; Introduction Diarrhoeal disease is a common cause of death in the tropical countries and it is the second mostly causing infant deaths worldwide. Shigella is one of the well-studied human pathogens

• towards the preparation of glycoconjugates, we report herein a convergent chemical synthesis of the tetrasaccharide as its 4-methoxyphenyl glycoside 1 corresponding to the O-antigen of Shigella boydii type 9 using a [2 + 2] block glycosylation strategy (Figure 2). Results and Discussion The convergent

• synthesis of the target tetrasaccharide 1 as its 4-methoxyphenyl glycoside has been achieved applying a number of recently developed elegant reaction methodologies. A number of notable features are present in the synthetic strategy, which are (a) convergent [2 + 2] block glycosylation; (b) application of

Amine-linked diglycosides: Synthesis facilitated by the enhanced reactivity of allylic electrophiles, and glycosidase inhibition assays

• Ian Cumpstey,
• Jens Frigell,
• Elias Pershagen,
• Tashfeen Akhtar,
• Elena Moreno-Clavijo,
• Inmaculada Robina,
• Dominic S. Alonzi and
• Terry D. Butters

Beilstein J. Org. Chem. 2011, 7, 1115–1123, doi:10.3762/bjoc.7.128

• unsaturated glycoside 4 to be achieved; phosphomolybdic acid [32] gave the product (α:β, 8:1) in 63% yield. Deacetylation of 4 and regioselective silylation of the primary alcohol gave the threo allylic alcohol 2. The sulfonamide nucleophiles 6, 7 and 9 were prepared from the corresponding amines 5 [33] and 8

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• is a C-glycoside isomer of uridine and plays an important role in proteosynthesis. In organisms, pseudouridine is biosynthesized from uridine via the action of pseudouridine synthases. Nevertheless, the specific role of pseudouridines is still the subject of much research. In order to study

Synthesis of glycoconjugate fragments of mycobacterial phosphatidylinositol mannosides and lipomannan

• Benjamin Cao,
• Jonathan M. White and
• Spencer J. Williams

Beilstein J. Org. Chem. 2011, 7, 369–377, doi:10.3762/bjoc.7.47

• remaining hydroxyl groups afforded the glycoside 13, which was desilylated with HF·pyridine complex to yield 14. This chemoselective transformation uses conditions that are similar to those reported by Tam et al. [23], and result in desilylation in a significantly shorter period than that previously

• reported using HCl in MeOH/Et2O [22]. The diol 15 was prepared by treatment of 12 with 2,3-butanedione and trimethyl orthoformate in the presence of catalytic acid in refluxing MeOH (Scheme 2) [37]. Trace amounts of the corresponding methyl glycoside were also obtained, arising from limited methanolysis of

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• . This procedure has been successfully used to prepare C-aryl glycoside from C-alkynyl glycoside and ethylene according to an EYCM/Diels–Alder/oxidation sequence (Scheme 6) [52][53]. The selective cyclopropanation of the most electron deficient double bond of the unsymmetrical dienic system has been

Catalysis: transition-state molecular recognition?

• Ian H. Williams

Beilstein J. Org. Chem. 2010, 6, 1026–1034, doi:10.3762/bjoc.6.117

• cases of methyl transfer and of glycoside hydrolysis to illustrate and to update the same theme from a computational point of view. Discussion The transition state is of strategic importance within the field of chemical reactivity. Owing to its location in the region of the highest energy point on the

• − ΔGRint by virtue of the differential distortion energy ΔGTdist − ΔGRdist. TS recognition in enzymic glycoside hydrolysis The endo-1,4-β-xylanase (BCX) from Bacillus circulans catalyses the hydrolysis of xylan and β-xylobiosides with net retention of anomeric configuration by means of a double

New amphiphilic glycopolymers by click functionalization of random copolymers – application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin

• Otman Otman,
• Paul Boullanger,
• Eric Drockenmuller and
• Thierry Hamaide

Beilstein J. Org. Chem. 2010, 6, No. 58, doi:10.3762/bjoc.6.58

• best result was obtained with commercially available triethylene glycol monochloride. Thus, peracetylated mannose 1 was reacted with triethyleneglycol monochloride, in the presence of boron trifluoride etherate to afford glycoside 2 [12] in 50–55% yield. After purification, the latter was converted to

Synthesis of lipophilic 1-deoxygalactonojirimycin derivatives as D-galactosidase inhibitors

• Georg Schitter,
• Elisabeth Scheucher,
• Andreas J. Steiner,
• Arnold E. Stütz,
• Martin Thonhofer,
• Chris A. Tarling,
• Stephen G. Withers,
• Jacqueline Wicki,
• Katrin Fantur,
• Eduard Paschke,
• Don J. Mahuran,
• Brigitte A. Rigat,
• Michael Tropak and
• Tanja M. Wrodnigg

Beilstein J. Org. Chem. 2010, 6, No. 21, doi:10.3762/bjoc.6.21

• study of glycoside-hydrolysing enzymes. These sugar mimetics have been found to have anti-viral, anti-cancer, anti-diabetes, anti-infective, as well as insect anti-feedant and plant growth regulatory effects. Because of their diverse properties, iminosugars have enjoyed continuous interest since their

• substituents of the new N-modified 1-galactonojirimycin derivatives on their biological interaction with respective glycoside hydrolases are described. Results and Discussion The key intermediate for the synthesis of N-modified lipophilic 1-deoxygalactonojirimycin derivatives 16–20 as well as 22 was the 3,4-O

(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• -deazaguanine (c7G), forms a 1:1 complex with pentameric adenyl DNA. Deazaguanine nucleobase was chosen because of the unique glycoside bond stability and its ability to prevent G-quartet formation. To increase the already strong binding of DNG to DNA, DNG was combined with a ligand capable of binding

Convergent syntheses of Le^X analogues

• An Wang,
• Jenifer Hendel and
• France-Isabelle Auzanneau

Beilstein J. Org. Chem. 2010, 6, No. 17, doi:10.3762/bjoc.6.17

• respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly

• , the reaction mixture was either stirred for 1 h at 50 °C in an oil bath (Supporting Information File 1, Method A) or submitted to microwave irradiation for 5 min at 50 °C (Supporting Information File 1, Method B). After acetylation of the excess chlorohexanol to ease its removal, pure glycoside 14 was

• isolated in excellent yield whether method A or B was followed. Thus, these syntheses of glycoside 14 constitute efficient alternatives to that reported by Nitz et al. in which the starting material was the corresponding anomeric bromide [45]. Nucleophilic displacement of the chlorine atom in glycoside 14

Synthesis in the glycosciences

• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2010, 6, No. 16, doi:10.3762/bjoc.6.16

• . Since the isolation of those complex glycans which are active in cellular communication is problematic, oligosaccharide synthesis is an important area of research. Moreover, what Professor Hans Paulsen, one of the greatest exponents of glycoside synthesis, observed in 1982 [2] still holds true today

• syntheses”. It is therefore not surprising that the majority of contributions collected in this Thematic Series deal with methods, both chemical and enzymatic, for oligosaccharide synthesis. One approach to deal with the problem of glycoside synthesis is the preparation of so-called glycomimetics. This is a

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• D-ribose 193. Treatment of D-ribose in acetone with allylic alcohol in presence of catalytic amount of sulfuric acid provided the corresponding protected acetonide allyl glycoside. The primary alcohol was transformed into a N-Boc amine by successive Mitsunobu reaction, reduction and acylation to