Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• tetrasaccharide 74, which demonstrated its versatility and efficacy. Another study [43] showed that 1,6-anhydro sugars 76 and 78 could be synthesized by utilizing salient features of gold-catalyzed glycosidations. 2.2 Aldehydes and ketones as nucleophiles Different oxygen heterocycles can be obtained from the

Metathesis access to monocyclic iminocyclitol-based therapeutic agents

• Ileana Dragutan,
• Valerian Dragutan,
• Carmen Mitan,
• Hermanus C.M. Vosloo,
• Lionel Delaude and
• Albert Demonceau

Beilstein J. Org. Chem. 2011, 7, 699–716, doi:10.3762/bjoc.7.81

• , can be considered as carbohydrate mimics in which the endocyclic oxygen atom of sugars has been replaced by an imino group. This vast and highly diversified class has attracted considerable interest due to the remarkable biological profile shown by many of its members which has been detailed in a

• number of excellent books and reviews [1][2][3][4][5][6][7][8][9][10][11][12]. Natural iminosugars (i.e., alkaloids mimicking the structures of sugars, widespread in many plants or microorganisms) [12][13][14][15], as well as non-natural counterparts, are becoming important leads for drug development in

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

• of a 3,4-butanediacetal-protected mannoside. The azidooctyl groups of these synthetic mannans were elaborated to fluorescent glycoconjugates and squaric ester derivatives useful for further conjugation studies. Keywords: fluorescently-labelled sugars; glycoconjugates; lipomannan; mycobacteria

Preparation of aminoethyl glycosides for glycoconjugation

• Robert Šardzík,
• Gavin T. Noble,
• Martin J. Weissenborn,
• Andrew Martin,
• Simon J. Webb and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2010, 6, 699–703, doi:10.3762/bjoc.6.81

• general aminoethylation method that was applicable to all targets was found, which rather suggests that protocols need to be tailored for each sugar. Results and Discussion Coupling reactions Aminoethyl glycosides have previously been generated in a number of ways. Free sugars have been glycosylated with

• ], bromoethanol [16] or azidoethanol [17] and subsequently transformed into the amine. In the interest of finding fast reliable methods, we have investigated two general aminoethylation protocols: First, the direct glycosylation of peracetylated sugars, which can be either purchased or easily prepared from free

• sugars and can be used without purification. Where these proved to be unreactive, the anomeric acetates were converted to glycosyl bromides, usually in quantitative yields, and products were used without further purification. Where possible, N-Cbz-protected aminoethanol was used as the glycosyl acceptor

Addition of lithiated enol ethers to nitrones and subsequent Lewis acid induced cyclizations to enantiopure 3,6-dihydro-2H-pyrans – an approach to carbohydrate mimetics

• Fabian Pfrengle and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 75, doi:10.3762/bjoc.6.75

• ]. A final hydrogenation step gave aminopyran 30 in high overall yield. Aminopyrans 24, 26, 28 and 30 can be regarded as mimetics of differently configured (2-deoxy) 4-amino sugars [24][25][26]. Aminopyrans 24 and 28 have already been linked via amide bonds to the thiol shell of gold nanoparticles

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

• drawbacks inherent to polymer structures. Due to the high versatility of click chemistry in the presence of functional groups, it was then of interest to attempt the reaction with unprotected sugars. Moreover, this chemistry can be carried out not only in various organic solvents, but also in aqueous

Synthesis of glycosylated β³-homo-threonine conjugates for mucin-like glycopeptide antigen analogues

• Florian Karch and
• Anja Hoffmann-Röder

Beilstein J. Org. Chem. 2010, 6, No. 47, doi:10.3762/bjoc.6.47

• instance, stable TACA mimics comprising C-glycosides [11][12][13][14], S-glycosides [15][16][17][18][19] and deoxyfluoro sugars [20] have been used to circumvent hydrolytic degradation by endogenous glycosidases. In principle, antigenicity of the artificial TACA derivatives should be enhanced by minor

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

• any significant background fluorescence (Figure 1). In both the Neu5Hex fed HEp-2 and the incubation with Ac4GlcNAz a clear staining of the cellular glycocalyx at the expected wavelengths was observed. Conclusion Sialic acids are prominent sugars which are located in the terminal position on cell

(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

• ; 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

• ]. In addition, SAAs have been widely used in the field of material sciences as carbohydrate-derived monomers for the design of novel chiral polyamides [18]. Nevertheless, these review articles mainly focus on amide-linked sugars and do not pay too much attention to other types of pseudosugars. A

• notable exception is the contribution by Wessel and Dias Lucas, who recently published an interesting review where oligosaccharide mimetics which deviate from the natural linking pattern were discussed [19]. This review also included pseudoamide-linked sugars (Figure 1). In this current review we have

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

Synthesis of a new class of aminocyclitol analogues with the conduramine D-2 configuration

• Latif Kelebekli,
• Yunus Kara and
• Murat Celik

Beilstein J. Org. Chem. 2010, 6, No. 15, doi:10.3762/bjoc.6.15

• ]. Carba analogues of oligosaccharides (carbasugars), generated by replacing the endocyclic O-atom in a monosaccharide [1][2][3][4][5][6][7][8][9][10][11], are thought to be better drug candidates than natural sugars, since they are hydrolytically stable. Spurred on by the heightened interest in the design

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

• ][43][48][49][50]). Extractions of sugars 6b, 7b, 8b, 9 and 10 from the solid state into a CDCl3 solution of receptor 4 or 5 (1 mM) provided evidence for strong complexation of β-glucoside 6b and β-galactoside 8b. The extraction of solid methyl α-glucoside 7b, α-galactoside 9 and α-mannoside 10 into a

• CDCl3 solution of receptor 4 or 5 indicated a weaker binding of these sugars than that of 6b and 8b (see Table 1). The extraction experiments indicated that the imidazole-based receptor 4 is a more powerful carbohydrate receptor than the indole-based compound 5. Receptor 4 was able to dissolve about 1

• was carried out on silica gel 60 F254 plates employing chloroform/methanol mixtures as the mobile phase. Melting points are uncorrected. Sugars 6–11, 4(5)-imidazole-carbaldehyde (18) and 3-indole-carbaldehyde (19) are commercially available. General procedure for the synthesis of compounds 4 and 5: To

Acid- mediated reactions under microfluidic conditions: A new strategy for practical synthesis of biofunctional natural products

• Katsunori Tanaka and
• Koichi Fukase

Beilstein J. Org. Chem. 2009, 5, No. 40, doi:10.3762/bjoc.5.40

• preparing bioactive natural products [27][28][29][30][31][32][33]. Our successful examples are cation-mediated reactions, such as α-sialylation [28][32], β-mannosylation [31], and reductive opening of the benzylidene acetal groups in sugars [30], for which improved procedure under the microfluidic

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• materials (e.g. amino acids, sugars, tartaric acid, etc.) or on asymmetric reactions {e.g. Sharpless asymmetric epoxidation (AE), Sharpless asymmetric dihydroxylation (AD), diastereoselective Williamson etherification, etc.}. Semi-synthesis of natural ACGs as well as derivatised ACGs (e.g. amines, esters

Part 1. Reduction of S-alkyl- thionocarbonates and related compounds in the presence of trialkylboranes/air

• Jean Boivin and
• Van Tai Nguyen

Beilstein J. Org. Chem. 2007, 3, No. 45, doi:10.1186/1860-5397-3-45

• such as sugars.[3] On the other hand, iodides and S-alkylxanthates are useful compounds that easily produce carbon radicals involved in radical chain reactions (cyclisation, intermolecular addition onto an olefin, etc) in which trapping of the final radical results in the transfer of the iodine atom or

• reduction. In this context, the Surzur-Tanner/Giese rearrangement was particularly illustrative. [22][23][24][25] The 2 → 1 migration of the acyloxy group in glycosyl radicals is well documented and allows an easy preparation of 2-deoxy-sugars. At 20°C in 1,2-dichloroethane, a 50/50 mixture of the "regular

An efficient synthesis of tetramic acid derivatives with extended conjugation from L-Ascorbic Acid

• Biswajit K. Singh,
• Surendra S. Bisht and
• Rama P. Tripathi

Beilstein J. Org. Chem. 2006, 2, No. 24, doi:10.1186/1860-5397-2-24

• of multi-step solid and solution phase syntheses exist for the preparation of both achiral and chiral tetramic acid derivatives. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] In an ongoing programme towards the development of new antitubercular agents from sugars, we have been

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

• not occur in compounds 3, 4 or 5 under fluoride-catalysed desilylation conditions and as a result no intramolecular migration products were observed. However, for all sugars, a small proportion of bis-acetylated (compounds c) and non-acetylated (compounds d) compounds have also been isolated (Table 3

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

• stability, along with enhanced chemical and thermal stability properties. Recent reports have highlighted the potential of ionic liquids to be used as an ideal solvent for acetylation, ortho-esterification and benzylidenation of sugars,[4][5][6] and for certain glycosylation reactions. Sasaki et al

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

• glycosidases have been carried out. For these C8-glycomimetics, weak activities were observed, which can probably be explained by a too high conformational flexibility of such structures. Experimental See Supporting Information File 1. Sugars, iminosugars and carbasugars. Retrosynthetic analysis. 1D proton NMR

Towards practical biocatalytic Baeyer- Villiger reactions: applying a thermostable enzyme in the gram- scale synthesis of optically- active lactones in a two-liquid- phase system

• Frank Schulz,
• François Leca,
• Frank Hollmann and
• Manfred T. Reetz

Beilstein J. Org. Chem. 2005, 1, No. 10, doi:10.1186/1860-5397-1-10

• homogeneity.[56] In order to stabilize the production enzyme in the presence of an organic phase, we evaluated various buffer additives such as sugars, non-ionic detergents, and bovine serum albumin (BSA) which are known to exert beneficial effects on other enzymes.[57] The most pronounced effect on the