Flow synthesis of a versatile fructosamine mimic and quenching studies of a fructose transport probe

• Matthew B. Plutschack,
• D. Tyler McQuade,
• Giulio Valenti and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 2022–2027, doi:10.3762/bjoc.9.238

• overexpress Glut5 and poorly transported into cells known to express little Glut5 [2][5][18]. We demonstrated that the transport is inhibited by fructose but not by other dietary sugars (glucose, glucosamine) [17]. Furthering our understanding of fluorescent probes like NBDM will expedite the development of

• colorimetric cytotoxicity assays as well as in vitro staining [25][26][27][28]. To better understand the behaviour of NBDM, we measured fluorescence at various concentrations and in the presence of various dyes, amino acids and sugars. The absorption and emission spectra are shown in Figure 1. The quenching

• carbohydrate concentrations. This issue is significant because sugar uptake studies are often performed in the presences of added non-labeled sugars such as glucose, fructose or glucosamine. To assess our hypothesis, we measured the fluorescence of NBDM in the presence of glucose, fructose and glucosamine. No

Straightforward synthesis of a tetrasaccharide repeating unit corresponding to the O-antigen of Escherichia coli O16

• Manas Jana and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 1757–1762, doi:10.3762/bjoc.9.203

• intermediates were prepared from the commercially available reducing sugars by using a number of recently developed reaction conditions (Figure 2). The notable features of the synthetic strategy include, (a) the use of thioglycosides as glycosyl donors in all glycosylation reactions; (b) the application of

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

• Guillaume Moreira,
• Laurence Charles,
• Mohamed Major,
• Florence Vacandio,
• Yohann Guillaneuf,
• Catherine Lefay and
• Didier Gigmes

Beilstein J. Org. Chem. 2013, 9, 1589–1600, doi:10.3762/bjoc.9.181

• of styrene derivatives. Another important property of TEMPO is that it is reduced by reducing sugars such as glucose [18]. The consumption of nitroxides by reducing agents such as a sugar or a polysaccharide is of prime importance when aiming at the synthesis of glycopolymers or the graft

• interaction of the SG1 with unprotected sugars leading to extra degradation of the nitroxide. Furthermore, these results are very encouraging to envision the modification of unprotected polysaccharides by grafting synthetic polymer chains by the SG1-based NMP technique. Stability of SG1 in the presence of

• unstable in the case of SG1. The successful nitroxide-mediated polymerization of styrene in DMA from an alkoxyamine based on cellobiose and SG1 confirmed the ability to perform SG1-based NMP in DMA (without lithium salts) in the presence of unprotected sugars, and consequently opened the way to the

Appel-reagent-mediated transformation of glycosyl hemiacetal derivatives into thioglycosides and glycosyl thiols

• Tamashree Ghosh,
• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 974–982, doi:10.3762/bjoc.9.112

• -thioglycosides and exclusively β-glycosyl thiols were formed under these conditions. The reaction conditions have been applied successfully for the preparation of thioglycosides and glycosyl thiols from D- and L-sugars as well as disaccharides. The stereochemistry of the anomeric centers of the thioglycosides

Short synthesis of the common trisaccharide core of kankanose and kankanoside isolated from Cistanche tubulosa

• Goutam Guchhait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 705–709, doi:10.3762/bjoc.9.80

• was synthesized from the suitably functionalized monosaccharide derivatives 2 [10], 3 [11], and 4 [12], which were prepared from the commercially available reducing sugars (Figure 1). The key features of this synthetic strategy are (a) the application of two regioselective glycosylations by using

End-labeled amino terminated monotelechelic glycopolymers generated by ROMP and Cu(I)-catalyzed azide–alkyne cycloaddition

• Ronald Okoth and
• Amit Basu

Beilstein J. Org. Chem. 2013, 9, 608–612, doi:10.3762/bjoc.9.66

• accomplished by amidation with an azido-amine linker followed by Cu(I)-catalyzed azide–alkyne cycloaddition with propargyl sugars. Subsequent Teoc deprotection and conjugation with pyrenyl isothiocyanates afforded well-defined end-labeled glycopolymers. Keywords: capping agent; carbohydrate; glycan; olefin

De novo synthesis of D- and L-fucosamine containing disaccharides

• Daniele Leonori and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 332–341, doi:10.3762/bjoc.9.38

• sugars [34][35][36][37][38][39][40][41][42][43] provides an attractive alternative for rapid access to the required building blocks, but this approach has not been reported for D- or L-fucosamine [29][30][31][32][33][44][45][46]. Here, a full account of the de novo synthesis of differentially protected D

Efficient synthesis of phenylene-ethynylene rods and their use as rigid spacers in divalent inhibitors

• Francesca Pertici,
• Norbert Varga,
• Arnoud van Duijn,
• Matias Rey-Carrizo,
• Anna Bernardi and
• Roland J. Pieters

Beilstein J. Org. Chem. 2013, 9, 215–222, doi:10.3762/bjoc.9.25

• hydrophilic than simple sugars. We have been developing pseudo-disaccharide molecules such as 23 [32] (Scheme 7) as mimics of mannose disaccharides for the interaction with DC-SIGN and other C-lectins [33][34][35]. This molecule and its derivatives [36] contain lipophilic moieties that generally increase

Peptoids and polyamines going sweet: Modular synthesis of glycosylated peptoids and polyamines using click chemistry

• Daniel Fürniss,
• Timo Mack,
• Frank Hahn,
• Sidonie B. L. Vollrath,
• Katarzyna Koroniak,
• Ute Schepers and
• Stefan Bräse

Beilstein J. Org. Chem. 2013, 9, 56–63, doi:10.3762/bjoc.9.7

• fast methods for the decoration of biomimetic molecules with sugars is of fundamental importance. The glycosylation of peptoids and polyamines as examples of such biomimetic molecules is reported here. The method uses Cu-catalyzed azide alkyne cycloaddition to promote the reaction of azidosugars with

• azide alkyne cycloadditions. In addition, the up-scaling of some particular azide-modified sugars is described. Keywords: click chemistry; glycans; peptoids; polyalkynes; polyamines; solid-phase chemistry; Introduction To date, oligosaccharides have gained more and more interest as potential drugs in

• peptoid synthesis and decoration with sugars. As a model compound we started with the synthesis of a hexaglycosylated peptoid hexamer. Therefore, we synthesized a hexaalkynated peptoid structure 26,27 on resin (Scheme 3). The synthesis of a hexaalkynated peptoid backbone 26,27 was carried out on Rink or

Synthesis of a derivative of α-D-Glcp(1->2)-D-Galf suitable for further glycosylation and of α-D-Glcp(1->2)-D-Gal, a disaccharide fragment obtained from varianose

• Carla Marino,
• Carlos Lima,
• Karina Mariño and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2012, 8, 2142–2148, doi:10.3762/bjoc.8.241

• HPAEC–PAD Varianose was isolated from a culture of Penicillium varians [3] and its identity was proved by methylation and GLC–MS analysis. D-Galactose, D-mannose and D-glucose in the ratio 70:15:15 and the corresponding diagnostic peaks for the methylated sugars were observed, as previously described [4

Convergent synthesis of the tetrasaccharide repeating unit of the cell wall lipopolysaccharide of Escherichia coli O40

• Abhijit Sau and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2012, 8, 2053–2059, doi:10.3762/bjoc.8.230

• the suitably protected monosaccharide derivatives 2 [13], 3 [14], 4 [15] and 5 [16], which were prepared from the commercially available reducing sugars, by applying a series of functional group protection–deprotection methodologies (Figure 2). The synthetic strategy has a number of notable features

Synthesis and antifungal properties of papulacandin derivatives

• Marjolein van der Kaaden,
• Eefjan Breukink and
• Roland J. Pieters

Beilstein J. Org. Chem. 2012, 8, 732–737, doi:10.3762/bjoc.8.82

• -1042 [25], corynecandin [26][27] and the F-10748 series [28]. These structures vary mostly with respect to the two partially unsaturated acyl chains on the sugars. Small changes in these fatty acid tails have only small effects on the activity. However, more drastic changes in these tails or the lack

Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

• Christiane E. Kupper,
• Ruben R. Rosencrantz,
• Birgit Henßen,
• Helena Pelantová,
• Stephan Thönes,
• Anna Drozdová,
• Vladimir Křen and
• Lothar Elling

Beilstein J. Org. Chem. 2012, 8, 712–725, doi:10.3762/bjoc.8.80

• and final product were analysed with HPLC, method B. Deprotection of heptasaccharide–linker–NH2: synthesis of 17 Deprotection of the poly-LacNAc oligomer (17) was performed as described previously, except that sugars were not lyophilised but instead dissolved in water and stored at −20 °C [55

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

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

• that the simple method will allow us to prepare a variety of α-glycolipid antigens other than GGPLs and to prove their biological significance [43]. By the 1H NMR conformational analysis, which was based on our former studies on deuterium-labeled sn-glycerols and sugars, we have proven that GGPL-I and

Branching out at C-2 of septanosides. Synthesis of 2-deoxy-2-C-alkyl/aryl septanosides from a bromo-oxepine

• Supriya Dey and
• Narayanaswamy Jayaraman

Beilstein J. Org. Chem. 2012, 8, 522–527, doi:10.3762/bjoc.8.59

• bond formation with alkyl and aryl substituents. Keywords: C–C bond formations; 2-deoxy sugars; organometallic reactions; septanosides; unsaturated sugars; Introduction Septanoses and septanosides are unnatural, seven-membered cyclic sugars [1]. Methods of preparation and the exploration of the

• properties of these unnatural sugars are of high interest [2]. An early isolation of septanose was achieved through cyclization of generic hexose sugars, which afforded minor amounts of septanose, along with furanose and pyranose, which formed in major amounts [3]. Synthetic approaches to septanoses have

• metathesis reactions of appropriately installed diene derivatives [11][12][13]; (iv) ring expansion of 1,2-cyclopropanated sugars [14][15][16][17]; (v) Baeyer–Villiger oxidation of inositol derivatives [18][19] and (vi) electrophile-induced cyclization [20]. We recently developed a new methodology to prepare

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

• 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

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

• different sugar units instead of a single motif, namely heteroglycocluster, reflects the presence of sugars found in native biological systems more closely than homoglycocluster does. Although recognition mechanisms are not fully understood, these studies suggest that heteroglycoclusters should interact

• with proteins through distinct binding sites, which may influence both affinity and selectivity [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. In this context, we previously reported a combinatorial procedure to prepare libraries of heteroglycoclusters displaying sugars and/or amino

• heteroglycoclusters by using a protocol based on orthogonal chemoselective ligations. Two series of compounds containing different combinations of two different sugars have been designed (Figure 1). In one series (heteroglycocluster 2:2), two αMan, αFuc and/or βLac are conjugated at alternate positions into the

Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• BC when the ancient Sumerians and Babylonians practiced the brewing of beer and winemaking [6]. Indeed, in vivo fermentation of sugars to ethanol by yeast is a complex process involving at least 12 enzymes and 2 cofactors, NAD+ and ADP. Nowadays microbial biotransformations have become an

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

• reaction was much less regioselective than the Mitsunobu couplings. Moreover, the major regioisomer in the palladium-catalysed reaction was the 2-amino sugar, whereas in the Mitsunobu reactions, the 4-amino sugars were formed exclusively. A small amount of stereochemical scrambling of an intermediate π

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