Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid

• Arne Homann,
• Riaz-ul Qamar,
• Sevnur Serim,
• Petra Dersch and
• Jürgen Seibel

Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24

• , functionalized carbohydrates both in vitro and in vivo [2][3]. Acetylated monosaccharides, for example 2-azidoacetylamino-2-deoxy-1,3,4,6-tetraacetyl-β-D-glucopyranoside (Ac4GlcNAz, 16), are believed to permeate the cell membrane by diffusion processes [4]. Recently, it was reported that neuraminic acid

• through the membrane of eukaryotic cells [3]. Neu5Hex (3) is a new substrate for metabolic glycoengineering which is proposed to be incorporated into the cell surface glycan structures. It was shown that carbohydrates in growth media contribute to alterations in glycosylation patterns in human cells [8

• -functionalized carbohydrates in the glycocalyx are specifically addressed by complementary functionalized fluorescence agents 9-[2-carboxy-4-[(2-propyn-1-ylamino)carbonyl]phenyl]-3,6-bis(dimethylamino)xanthylium, alkynylated TAMRA or benzoic acid 2-[6-(3-azidopropanyloxy)-3-oxo-3H-xanthen-9-yl] 3-azidopropanyl

Bis(oxazolines) based on glycopyranosides – steric, configurational and conformational influences on stereoselectivity

• Tobias Minuth and
• Mike M. K. Boysen

Beilstein J. Org. Chem. 2010, 6, No. 23, doi:10.3762/bjoc.6.23

• revealed strong steric and configurational effects of position 3 on asymmetric induction, further dramatic effects of the pyranose conformation were also observed. Keywords: asymmetric synthesis; carbohydrates; copper; cyclopropanation; ligand design; Introduction The design and optimisation of chiral

• ligands for metal catalysed transformations is of crucial importance for stereoselective synthesis and is therefore an active field of research. In this context, carbohydrates are interesting, even if comparatively rarely used as starting materials for the preparation of new chiral ligand structures

(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

• carbohydrates. Such oligosaccharide mimetics are potential therapeutic agents against HIV and other infections, against cancer, diabetes and other metabolic diseases. An efficient strategy to access this type of compounds is the replacement of the glycosidic linkage by amide or pseudoamide functions such as

• ; glycomimetics; pseudooligosaccharides; spaced sugars; Review Among the major classes of biomolecules, carbohydrates are characterized by nearly unlimited structural diversity. Monosaccharide units can combine to produce oligosaccharides in a number of permutations that increases rapidly with the number of

• proteins [5][6][7], cell–cell communication [8] and immune response to pathogens [7][9][10][11]. However, the application of oligosaccharides as potential therapeutic agents has its main drawback in the low instability of natural carbohydrates in biological systems. In addition, solid phase synthesis of

Benzyne arylation of oxathiane glycosyl donors

• Martin A. Fascione and
• W. Bruce Turnbull

Beilstein J. Org. Chem. 2010, 6, No. 19, doi:10.3762/bjoc.6.19

• ; stereoselective glycosylations; Introduction Carbohydrates play important roles in many biological processes including tumour metastasis [1][2], bacterial and viral recognition [3][4][5], and the immunological response [6][7][8]. In order to obtain pure samples of oligosaccharides for biological studies

Synthesis in the glycosciences

• Thisbe K. Lindhorst

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

• Thisbe K. Lindhorst Otto Diels Institute of Organic Chemistry, Christiana Albertina University of Kiel, Otto-Hahn-Platz 3/4, 24098 Kiel, Germany 10.3762/bjoc.6.16 All cells are coated in carbohydrates and glycoconjugates. Today, after decades where sugars were regarded mainly as a means of energy

• storage or simply as molecular material, it is now known that carbohydrates are deeply involved in cellular communication. This awareness of the biological importance of carbohydrates has led to glycosciences becoming an intriguing and fascinating field of interdisciplinary research. However, the

Recognition properties of receptors consisting of imidazole and indole recognition units towards carbohydrates

• Monika Mazik and
• André Hartmann

Beilstein J. Org. Chem. 2010, 6, No. 9, doi:10.3762/bjoc.6.9

• units as the entities used in nature, and 2-aminopyridine group as a heterocyclic analogue of the asparagine/glutamine primary amide side chain, were prepared and their binding properties towards carbohydrates were studied. The design of these receptors was inspired by the binding motifs observed in the

• crystal structures of protein–carbohydrate complexes. 1H NMR spectroscopic titrations in competitive and non-competitive media as well as binding studies in two-phase systems, such as dissolution of solid carbohydrates in apolar media, revealed both highly effective recognition of neutral carbohydrates

• selected carbohydrates are described and compared with those of the previously described receptors. Keywords: carbohydrates; hydrogen bonds; molecular recognition; receptors; supramolecular chemistry; Introduction Analysis of the binding motifs found in the crystal structures of protein–carbohydrate

Synthesis of chiral cyclohexanes and carbasugars by 6-exo-dig radical cyclisation reactions

• Rajeev K. Shrivastava,
• Elise Maudru,
• Gurdial Singh,
• Richard H. Wightman and
• Keith M. Morgan

Beilstein J. Org. Chem. 2008, 4, No. 43, doi:10.3762/bjoc.4.43

• of carbohydrates as precursors for highly functionalised carbocyclic rings systems has found wide utility in organic synthesis [1][2][3][4][5][6][7][8][9][10][11]. In particular there is a large amount of literature devoted to the synthesis of cyclopentanes [12][13] that employs a 5-exo-dig ring

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

• Frédéric R. Leroux,
• Baptiste Manteau,
• Jean-Pierre Vors and
• Sergiy Pazenok

Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13

• hypofluorite (FOCF3) to olefins [38]. The introduction of the trifluoromethoxy substituent into carbohydrates was realized using tris(dimethylamino)sulfonium trifluoromethoxide (TASOCF3) as OCF3-transfer reagent [39]. This compound can be prepared by reaction of carbonyl fluoride with tris(dimethylamino

• )sulfonium difluorotrimethylsilicate in anhydrous THF at −75 °C (Scheme 9) [40]. The trifluoromethoxide anion is a relatively poor nucleophile. However, when reacted with primary triflate esters of carbohydrates, the anion displaced the triflate under mild conditions. However, although aromatic

Investigation of acetyl migrations in furanosides

• O. P. Chevallier and
• M. E. Migaud

Beilstein J. Org. Chem. 2006, 2, No. 14, doi:10.1186/1860-5397-2-14

• ribosides, acyl migration could be prevented when desilylation was catalysed by cerium ammonium nitrate. Introduction Over the years, a number of methods aimed at achieving chemoselective acylation of carbohydrates have been developed.[1][2][3] In addition to the challenges encountered in the selective

• intermolecular trans-esterification was also taking place. To identify the reaction conditions and the structural features of the acetylated furanosides facilitating acetyl migration upon protecting group manipulation, the various protected carbohydrates (1–5) were treated with tetrabutyl ammonium fluoride (TBAF

Study of thioglycosylation in ionic liquids

• Jianguo Zhang and
• Arthur Ragauskas

Beilstein J. Org. Chem. 2006, 2, No. 12, doi:10.1186/1860-5397-2-12

• carbohydrates in [bmim]BF4 per se was not quenched with low molar equivalents of water, and [bmim]BF4 acted not only as reaction media, but may also performed like "molecular sieves" at the same time. The recyclability of [bmim]BF4 for thioglycosylation reactions was accessed by repeating the synthesis of 3a

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• glycosidase inhibitors obtained since this diversity is introduced in an ultimate step of the synthesis. Introduction There is a considerable interest in the design of molecules able to mimic carbohydrates which play critical roles in various biological events such as for example, cell-cell recognition and