A protecting group-free synthesis of the Colorado potato beetle pheromone

• Zhongtao Wu,
• Manuel Jäger,
• Jeffrey Buter and
• Adriaan J. Minnaard

Beilstein J. Org. Chem. 2013, 9, 2374–2377, doi:10.3762/bjoc.9.273

• of glycosides (Scheme 1) [14] and expected that the approach might also be applicable in the synthesis of (S)-1. Triol 3, with vicinal primary, secondary, and tertiary hydroxy groups should be a suitable substrate for chemoselective oxidation with catalyst 2, enabling a protecting group-free

Gold-catalyzed glycosidation for the synthesis of trisaccharides by applying the armed–disarmed strategy

• Abhijeet K. Kayastha and
• Srinivas Hotha

Beilstein J. Org. Chem. 2013, 9, 2147–2155, doi:10.3762/bjoc.9.252

• oligosaccharides. The gold catalysis for glycosidation reactions, in which alkynylated glycosides are used, has emerged as one of the versatile options in this regard. A cleavage of the interglycosidic bond that was thought to be due to the higher reaction temperature and the acidic medium was observed during the

• moiety were screened. It was found that 1-ethynylcyclohexanyl (Ech) glycosides are suitable for carrying out the glycosidation at 25 °C in the presence of 5 mol % each of AuCl3 and AgSbF6. Subsequently, Ech-glycosides were observed to be suitable for the synthesis of trisaccharides under gold catalysis

• still no universal glycosyl donor [17][18], although the first glycoside was reported by Emil Fischer more than a century ago. A series of observations in our laboratory led to the identification of a gold(III)-catalyzed glycosidation reaction that uses alkynyl glycosides as glycosyl donors [19][20][21

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• natural indolocarbazole compounds have been isolated from several bacteria and marine invertebrates either as their glycosides (26–29) or aglycones (30–33) [17]. Based on the number of glycosidic bonds linking the carbohydrate moiety to the isoindole framework, the latter can be divided into two

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

• David Benito-Alifonso,
• Rachel A. Jones,
• Anh-Tuan Tran,
• Hannah Woodward,
• Nichola Smith and
• M. Carmen Galan

Beilstein J. Org. Chem. 2013, 9, 1867–1872, doi:10.3762/bjoc.9.218

• ][11][12][13][14] than there are available for other types of glycosides and even fewer that lead to fragments ready to be conjugated to glycoarray platforms [15]. One of the most troublesome steps in previous approaches is the synthesis of the α-glycosidic linkage between 2-acetamido-2-deoxy-D

Synthesis of meso-substituted dihydro-1,3-oxazinoporphyrins

• Satyasheel Sharma and
• Mahendra Nath

Beilstein J. Org. Chem. 2013, 9, 496–502, doi:10.3762/bjoc.9.53

• derived from porphyrins [11][12]. Previously, a large number of these molecules have been synthesized by the coupling of diverse pharmaceutically important moieties, such as carbohydrates [13][14][15], amino acid residues [16][17][18][19], steroids [20][21], glycosides [22][23][24], nitroxyl derivatives

Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

• Alexej Bubnov,
• Miroslav Kašpar,
• Věra Hamplová,
• Ute Dawin and
• Frank Giesselmann

Beilstein J. Org. Chem. 2013, 9, 425–436, doi:10.3762/bjoc.9.45

• silver-containing thermotropic liquid-crystalline materials based on bis(stilbazole) silver(I) cation in association with the amphiphilic counter-ion lauryl sulfate exhibit lyotropic and thermotropic liquid-crystalline behaviour [20]. A series of monoalkyl glycosides possesses a very stable thermotropic

• in the mesomorphic behaviour of alkyl glycosides has been made recently [24]. The methyl 6-O-(n-acyl)-α-D-glucopyranosides, with chain lengths between dodecanoyl and hexadecanoyl exhibit a monotropic SmA phase (i.e., occurring explicitly on cooling) only [25]. Even though a lot has already been done

Synthesis and testing of the first azobenzene mannobioside as photoswitchable ligand for the bacterial lectin FimH

• Vijayanand Chandrasekaran,
• Katharina Kolbe,
• Femke Beiroth and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2013, 9, 223–233, doi:10.3762/bjoc.9.26

• adhesive surfaces. Keywords: azobenzene glycosides; bacterial adhesion; E/Z photoisomerisation; FimH antagonists; mannobiosides; molecular switches; sweet switches; Introduction Adhesion of bacteria to surfaces can be a severe problem both in vivo and in vitro. Hence, inhibition of bacterial adhesion by

• ) in order to make a photoswitchable FimH antagonist available. Photoirradiation of azobenzene glycosides at ~365 nm effects E→Z isomerisation of the N=N double bond, and thermal relaxation or irradiation at ~450 nm leads to Z→E back isomerisation [13][14]. In the case that the E→Z isomerisation

• , glycosylation of the key intermediate 10 by using the mannosyl donor 3 gave the desired mannobioside 11 in 76% yield. Finally, removal of the O-acetyl groups according to Zemplén led to the unprotected 1,3-linked target mannobioside α-D-Man-(1→3)-D-Man (2). With the two azobenzene glycosides 6 and 2 at hand

A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors

• El Sayed H. El Ashry,
• El Sayed H. El Tamany,
• Mohy El Din Abdel Fattah,
• Mohamed R. E. Aly,
• Ahmed T. A. Boraei and
• Axel Duerkop

Beilstein J. Org. Chem. 2013, 9, 135–146, doi:10.3762/bjoc.9.16

• , Germany 10.3762/bjoc.9.16 Abstract Glycosylations of 5-(1H-indol-2-yl)-1,3,4-oxadiazoline-2(3H)-thione delivered various degrees of S- and/or N-glycosides depending on the reaction conditions. S-Glycosides were obtained regiospecifically by grinding oxadiazolinethiones with acylated α-D-glycosyl halides

• in basic alumina, whereas 3-N-(glycosyl)oxadiazolinethiones were selectively obtained by reaction with HgCl2 followed by heating the resultant chloromercuric salt with α-D-glycosyl halides in toluene under reflux. On using Et3N or K2CO3 as a base, mixtures of S- (major degree) and N-glycosides (minor

• purification of mixtures of S- or N-glycosides to obtain the pure N-glycosides. The aminolysis of the respective S- or N-glycosides with ammonia in aqueous methanol served as further confirmation of their structures. While in S-glycosides the glycosyl moiety was cleaved off again, 3-N-(glycosyl

Acylsulfonamide safety-catch linker: promise and limitations for solid–phase oligosaccharide synthesis

• Jian Yin,
• Steffen Eller,
• Mayeul Collot and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 2067–2071, doi:10.3762/bjoc.8.232

• the fast release and analysis of glycosides. Linker-functionalized resin 11 contains both cleavage sites, and was accessed by coupling the cesium salt of linker 10 with Merrifield chloride resin prior to capping and deprotection (Scheme 2). A second resin 12, containing only the safety-catch cleavage

The Amadori rearrangement as glycoconjugation method: Synthesis of non-natural C-glycosyl type glycoconjugates

• Katharina Gallas,
• Gerit Pototschnig,
• Florian Adanitsch,
• Arnold E. Stütz and
• Tanja M. Wrodnigg

Beilstein J. Org. Chem. 2012, 8, 1619–1629, doi:10.3762/bjoc.8.185

• chemical stability towards physiological hydrolysis of the glycosidic linkage, compared to the naturally occurring O- as well as N-glycosides [26]. A broad application of this reaction is not feasible as yet. However, according to its mechanism, the scope of the Amadori rearrangement could well comprise a

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

• methylated aryl O-, S-, N- and C-glycosides of D-glucopyranose and D-mannopyranose with hexacarbonylchromium. All tricarbonylchromium complexes were fully characterized. The structures of nine crystalline complexes were determined by X-ray diffraction, revealing unusual intra- and intermolecular nonclassical

• hydrogen bonds. Keywords: aryl glycosides; carbohydrates; transition-metal complex; tricarbonyl(arene)chromium; Introduction In 1957, Fischer and Öfele published the preparation of tricarbonyl(η6-benzene)chromium, which was the first arene tricarbonylchromium complex [1]. Since then, a plethora of

• reactions [9][10][11][12]. Tricarbonylchromium complexes of type C and D were obtained via benzannulation of glucal-derived pentacarbonylchromium carbenes or by reaction of alkynyl C-glycosides with pentacarbonylchromium carbenes [13]. Further syntheses and characterizations of more examples of carbohydrate

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

• diastereomeric (monovalent) C-glycosidic Con A ligands displayed only a small difference in the free energies of binding to Con A, a sizable difference was measured between the corresponding multivalent C-glycosides (calculated per monovalent ligand within the glycopolymer). Such effects can be analyzed in the

Triterpenoid saponins from the roots of Acanthophyllum gypsophiloides Regel

• Elena A. Khatuntseva,
• Vladimir M. Men’shov,
• Alexander S. Shashkov,
• Yury E. Tsvetkov,
• Rodion N. Stepanenko,
• Raymonda Ya. Vlasenko,
• Elvira E. Shults,
• Genrikh A. Tolstikov,
• Tatjana G. Tolstikova,
• Dimitri S. Baev,
• Vasiliy A. Kaledin,
• Nelli A. Popova,
• Valeriy P. Nikolin,
• Pavel P. Laktionov,
• Anna V. Cherepanova,
• Tatiana V. Kulakovskaya,
• Ekaterina V. Kulakovskaya and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2012, 8, 763–775, doi:10.3762/bjoc.8.87

• , consistent with the molecular formula С75H118O39. GLC analysis of the acetylated (S)-2-octyl glycosides derived after full acid hydrolysis of compound 1 revealed the presence of D-galactose (D-Gal), L-arabinose (L-Ara), 6-deoxy-D-glucose (D-Qui), D-xylose (D-Xyl), L-rhamnose (L-Rha), D-fucose (D-Fuc), and D

• methanol and the slurry was diluted with acetone (160 mL). The formed precipitate was filtered and dried to give 22.2 g of total glycosides (fraction B). Combined fractions A and B (36.7 g) were subjected to preparative HPLC (Ascentis C18, 5 μm, 250 × 21.2 mm) using a mixture of 65% methanol and 35% 0.05 M

• analyses. Compounds 1 and 2 were hydrolyzed with 2 M CF3CO2H (120 °C, 2 h) and the absolute configurations of the monosaccharides were determined by GLC of acetylated (S)-(+)-2-octyl glycosides according to the published method [29]. GLC was performed using an Agilent 7820A chromatograph equipped with an

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

• -mercaptoundecanoic acid (1), which is tritylated with 2 in a straightforward synthesis, in 98% yield, following the procedure of Kovács et al. [23] (Scheme 1). The acid 3 was coupled with either of the aminoethyl glycosides 4 [24][25][26] or the GlcNAc derivative 6 [27], which were prepared according to literature

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

• glycals using several aromatic and aliphatic alkynes. This Pd-catalyzed cross-coupling reaction presents a facile access to alkynyl C-glycosides and sets the stage for a reductive/oxidative refunctionalization of the enyne moiety to regenerate either C-glycosidic structures or pyran derivatives with a

• substituent in position 2. Keywords: C-glycosides; enyne; glycals; reductive/oxidative refunctionalization; Sonogashira–Hagihara reaction; Introduction Carbohydrates are key players in a plethora of biological processes, such as cell-development, metastasis, cell–cell aggregation and viral infection [1][2

• , modified mono- or disaccharides have come into the focus of medicinal chemists [8][9]. An important class of carbohydrate mimetics are the C-glycosides [10][11][12][13]. In such compounds the oxygen of the O-glycosidic bond is substituted by a methylene unit rendering them stable to enzymatic degradation

Phytoalexins of the Pyrinae: Biphenyls and dibenzofurans

• Cornelia Chizzali and
• Ludger Beerhues

Beilstein J. Org. Chem. 2012, 8, 613–620, doi:10.3762/bjoc.8.68

• 34 species of the Pyrinae, only Sorbus aucuparia formed a phytoalexin, namely aucuparin (3) [20]. Another abiotic elicitor, mercury, caused accumulation of 4'-methoxyaucuparin (10) in Rhaphiolepis umbellata at concentrations higher than after fungal infection [14][19]. So far, no glycosides of

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

• orthogonality was shown for O-pentenyl versus O-propargyl glycosides by Hotha et al. [17] and for S-glycosyl O-methyl phenylcarbamothioate (SNea) versus thioglycosides/thioimidates by us [18], but still their applicability to multistep synthesis remains to be proven. Working to expand this concept, our group

• oligosaccharide synthesis [6]. However, suitable reaction conditions for the orthogonal activation of these two classes of leaving groups are yet to be found. Commonly, O-glycosides are too stable to be used as effective glycosyl donors [21]. Pent-4-enyl O-glycosides introduced by Fraser-Reid are unique in this

• part of the ongoing research effort to develop versatile building blocks, we present herein the development of a new ortho-allylphenyl (AP) leaving group. In line with other efforts [23][24][25][26], the AP group was specifically designed to address the drawbacks of O-pentenyl glycosides and to create

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

• , Wako, Saitama 351-0198, Japan 10.3762/bjoc.8.52 Abstract Glycosyl triflates with a 2,3-oxazolidinone protecting group were generated from thioglycosides by low-temperature electrochemical oxidation. The glycosyl triflates reacted with alcohols to give the corresponding glycosides β-selectively at low

• amino sugars [7][8], the selectivity highly depends on the nature of the glycosyl acceptors and reaction conditions. In the last decade, 2,3-oxazolidinone protected 2-amino-2-deoxy-glycosides have been developed as glycosyl donors for the stereoselective synthesis of amino sugars [9][10][11][12][13][14

• ][15][16][17][18][19][20][21][22][23][24]. These glycosyl donors afford the corresponding glycosides in a 1,2-trans or 1,2-cis selective manner by action with various types of glycosyl acceptors. However, it is still uncertain whether glycosyl triflate intermediates [25], which were detected by 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

• partly to the content of ManNAc. Thus, ManNAc units play a significant role in bacterial pathogenicity and virulence (e.g., Streptococcus pneumoniae) [4][5]. Surprisingly, glycosidases active upon β-ManpNAc and α-ManpNAc glycosides are not known so far. Therefore, the building blocks for the chemical

• preparation of glycoproteins [9][10], various alcohol glycosides [11][12], phosphates [13] and oligosaccharides [12]. To the best of our knowledge, glycosylation of phenolic OH with oxazoline has not been accomplished so far. Therefore, we decided to test oxazoline 3 [14] glycosylation in our synthetic

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

• propargyl [41] glycosides 1-3 (Figure 1) and the cyclopeptide 4 (Scheme 1). This scaffold containing two lysines (Lys) functionalized with an aldehyde and two norleucines (Nle) bearing an azide group was prepared by using a strategy adapted from the procedure described previously [42]. In the first step

• observed that a tetravalent glycocluster can be obtained in good yields and as a unique 1,4-regioisomer by using a catalytic amount of copper micropowder in a mixture of isopropanol and ammonium acetate buffer [42]. Therefore we decided to follow similar conditions in this study with propargyl glycosides

• CuAAC reactions were subsequently performed with propargyl glycosides αMan 1b, αFuc 2b and βLac 3b as described above (Scheme 2). No difference in reactivity from the previous 2:2 series was observed, thereby confirming the efficiency of this strategy for the preparation of well-defined

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

• glucosyl moieties was mainly responsible for the observed regioselectivity and anomeric selectivity of the ring-closing glycosylation step. Keywords: intramolecular glycosylation; molecular modeling; prearranged glycosides; Introduction Intramolecular O-glycosidic bond formation of tethered glycosyl

• donors and acceptors (prearranged glycosides) resembles to some extent enzyme-catalyzed glycosylation reactions where the glycosyl donor and glycosyl acceptor are first bound in the active site of an enzyme and thus, the glycosidic bond forms intramolecularly. Three different concepts for the

• mannosylations that double diastereodifferentiation is responsible in part for the anomeric selectivity of such intramolecular glycosylations, although the exact cause of this effect has not been unambiguously identified so far [27]. Therefore, we prepared a series of prearranged glycosides constructed out of a

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

• in the presence of propargyl glycosides and propargyl ethers was developed [41]. Recently, Li et al. reported the gold(I)-catalyzed glycosylation with glycosyl ortho-alkynylbenzoates 73 as donors [42]. This glycosylation protocol was used in an efficient synthesis of a cyclic triterpene

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

• synthesis. Synthesis of bis heterocyclic derivatives Sarfati and co-workers published an interesting and facile synthesis of C-5 alkylated 2'-deoxyuridine and uridine derivatives [40]. The C-5 position can be substituted by glycosides of either 2-acetamido-2-deoxy-β-D-glucopyranose or α-D-mannopyranose. All

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

• –alkyne cycloaddition (CuAAC) reaction [33][34]. Results and Discussion Since their introduction by Palcic and co-workers [35], hydrophobic alkyl glycosides have proven to be valuable derivatives for enzymatic assays, as their lipophilic nature allows easy product isolation by either reversed-phase

• chromatography or simple solvent partitioning. Incorporation of an azidooctyl group confers many of the same benefits as an octyl aglycon, with the additional advantage that the azido group may be elaborated into glycoconjugates. However, the synthesis of azidooctyl glycosides can be challenging as the use of

• %). Orthoesters are common by-products of glycosylation reactions and typically rearrange under acidic conditions to give trans-linked glycosides [43]. Thus, 14 and 16 were treated with 0.25 equiv of an alternative Lewis acid, TMSOTf, and allowed to react for a longer time to allow the intermediate orthoester to

Carbasugar analogues of galactofuranosides: α-O-linked derivatives

• Jens Frigell and
• Ian Cumpstey

Beilstein J. Org. Chem. 2010, 6, 1127–1131, doi:10.3762/bjoc.6.129

• common than their β-linked anomers, from which they are distinguished by their 13C C1 chemical shifts (α, 103.8 ppm; β, 109.9 ppm for the methyl glycosides) [3], and 3J1,2 1H,1H coupling constants (α, 4 Hz; β, 2 Hz) [4]. Nevertheless, α-galactofuranosides occur as components of a number of