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

• azide during the scale-up of the reaction but this caused a decrease of the overall reaction yields. In all cases, the test reactions were performed starting from D-glucosamine hydrochloride as a model compound for the synthesis of 1,3,4,6-tetra-O-acetyl-N-azidoacetyl-D-glucosamine (Ac4GlcNAz = 1

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

• with either glucosamine thioglycoside 17 and glucosamine trichloroacetimidate 18 or perbenzylated thioglycoside 19, which are both important building blocks for the synthesis of heparin and heparan sulfate. Three repetitions of a glycosylation using each three equivalents trichloroacetimidate 18

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

• with alpha and beta linkage, one beta-linked D-glucosamine and one beta-linked D-mannosyl moiety (Figure 1). Although several therapeutics have appeared in the past to control the diarrheal epidemics caused by E. coli infections, emergence of resistant strains is a serious concern in the development of

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

• mixture of the unreacted lactone 4, the fully reduced alditol 6 as the main product, and a small amount of the desired aldoheptose 5 was formed. When N-acetyl-D-glucosamine was subjected to this reduction method, the corresponding heptitol 6 was isolated as the main product under all conditions tried

Automated synthesis of sialylated oligosaccharides

• Davide Esposito,
• Mattan Hurevich,
• Bastien Castagner,
• Cheng-Chung Wang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 1601–1609, doi:10.3762/bjoc.8.183

• semi-protected oligosaccharide. The automated synthesis of 20 (Scheme 3) started with the glycosylation of resin-bound linker 17 with glucosamine building block 18 (2 × 5 equiv) [5] in the presence of N-iodosuccinimide and triflic acid. Fluorenylmethoxycarbonyl (Fmoc) removal was followed by

• 19. Analysis of the crude mixture by LC–MS showed incomplete glycosylation of the resin bound glucosamine by building block 4. The reaction was optimized to identify the best glycosylation conditions for building block 4 under the solid-phase paradigm. Performing the glycosylation at a higher

• been implicated in inflammation and cancer metastasis [26], and was chosen as a model glycan for the construction of branched compounds. Glucosamine building block 23, containing C3-levulinoyl (Lev) and C4-Fmoc protecting groups [27], was first reacted with the linker. The glycosylation was followed by

Synthesis of 4” manipulated Lewis X trisaccharide analogues

• Christopher J. Moore and
• France-Isabelle Auzanneau

Beilstein J. Org. Chem. 2012, 8, 1134–1143, doi:10.3762/bjoc.8.126

• that the reactivity of these donors towards the BF3·OEt2-promoted glycosylation at O-4 of the N-acetylglucosamine glycosyl acceptors followed the ranking 4-F > 4-OAc ≈ 4-OMe > 4-Cl. The resulting disaccharides were deprotected at O-3 of the glucosamine residue and fucosylated, giving access to the

• : (1) the galactosylation then fucosylation of a glucosamine acceptor [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47]; (2) the fucosylation then galactosylation of a glucosamine acceptor [48][49][50][51][52][53]; or (3) the fucosylation at O-3 of a lactosamine derivative

• 12 [56] and 13 [12] (Figure 2). Synthesis of monosaccharide building blocks 8–11 Glucosamine acceptor 8 was prepared in two steps from the known [14] benzylidene 7: the benzylidene acetal was first hydrolyzed, and then the resulting diol (79%) was selectively benzoylated at O-6 (BzCl-collidine

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• saccharides. Glycosaminoglycans (GAG) are long polysaccharide chains containing sulfated saccharides of uronic acids (either iduronic or glucuronic acid) and glucosamine or galactosamine as repetitive disaccharide units. GAGs exist at the cell-surface as well as in the ECM and are attached to proteins [16

Kinetic studies and predictions on the hydrolysis and aminolysis of esters of 2-S-phosphorylacetates

• Milena Trmčić and
• David R. W. Hodgson

Beilstein J. Org. Chem. 2010, 6, 732–741, doi:10.3762/bjoc.6.87

• a thiophosphate nucleophile from commonly used bromoacetate ester cross-linking agents. Results: We found cross-linking between uridine-5′-monophosphorothioate and D-glucosamine using N-hydroxybenzotriazole and N-hydroxysuccinimde bromoacetates to be ineffective. In order to gain insight into these

• preliminary studies into thiophosphate-amine cross-linking using both N-hydroxybenzotriazole 1 (R = Bt) and N-hydroxysuccinimde 1 (R = NHS) esters of bromoacetic acid with thiophosphate 4 and D-glucosamine as a representative thiophosphate and a representative amine, respectively (Scheme 2). A mixed water

• of pHs. D-Glucosamine was chosen as a model amine system to investigate these properties because of its relatively low pKaH of 7.75 [7]. Thus, even at relatively low pHs, a substantial proportion of the amine will be in its neutral, nucleophilic form. In addition, by structural analogy with

Synthesis of 6-PEtN-α-D-GalpNAc-(1–>6)-β-D-Galp-(1–>4)-β-D-GlcpNAc-(1–>3)-β-D-Galp-(1–>4)-β-D-Glcp, a Haemophilus influenzae lipopolysacharide structure, and biotin and protein conjugates thereof

• Andreas Sundgren,
• Martina Lahmann and
• Stefan Oscarson

Beilstein J. Org. Chem. 2010, 6, 704–708, doi:10.3762/bjoc.6.80

• -containing lactose derivative a suitably protected lacto-N-neotetraose tetrasaccharide structure was constructed through subsequential couplings with two thioglycoside donors, a glucosamine residue followed by a galactose derivative, using NIS/AgOTf as promoter. Removal of a silyl protecting group at the

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

• surfactants for mini-emulsion polymerization [5][6]. Amphiphilic block copolymers with pendant glucosamine units have been obtained by living cationic polymerization and their interaction with wheat germ agglutinin lectin investigated [7]. More recently, the synthesis of neoglycopolymers by living radical

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

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

• Tobias Minuth Mike M. K. Boysen Institute of Organic Chemistry, Gottfried-Wilhelm-Leibniz University of Hannover, Schneiderberg 1B, D-30167 Hannover, Germany 10.3762/bjoc.6.23 Abstract In previous studies we found that the asymmetric induction of bis(oxazolines) based on D-glucosamine strongly

• though N-acylated derivatives of D-glucosamine easily form bicyclic carbohydrate oxazolines, until recently only a few examples of mono(oxazoline) ligands [15][16][17] and the corresponding bis(oxazolines) [18] based on this monosaccharide have appeared in the literature. In the course of our work we

• have introduced new glucosamine-derived bis(oxazolines) 2a–c with uniform protective groups on all oxygen functions [19][20][21] and derivatives 3a–f with cyclic 4,6-O-benzylidene protection as well as various other 3-O-substituents that differ in steric demand and electronic nature [20][21]. These

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

• successive galactosylation then fucosylation of a glucosamine acceptor [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]; 2. a stepwise approach in which the sequence of glycosylation of the glucosamine acceptor is reversed, i.e. the fucosylation is followed by the galactosylation [28][29

• approach to prepare these Lex derivatives began with the galactosylation at O-4 of glycosyl acceptor 4 with the known [39][40][41] galactosyl donor 7 followed by deprotection at O-3 of the glucosamine residue and fucosylation of the resulting disaccharide with the known [42] ethylthioglycoside 9. Since in

• addition to the Lex trisaccharide we are also interested in preparing fragments of the dimLex antigen, we examined the glycosylation at O-4 of glucosamine glycosyl acceptors with galactosyl donor 8, which is chloroacetylated rather than acetylated at O-3. Finally, we also investigated the reactivity

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

• applied to β-mannoside synthesis [31][39][40][43][44][45]. We also have achieved excellent β-selectivity in the reaction of 4,6-O-benzylidenemannopyranosyl-N-phenyltrifluoroacetimidate (4) with N-Troc-glucosamine acceptor 5 (R = Bn, 93% yield, β : α = 95 : 5 on 20 mg scale) using the bulky and dual Lewis

• successful. Gratifyingly, by applying the established conditions above, the glucose, glucosamine, and galactose 4,6-O-benzylidene acetals 7–10 were selectively transformed into the corresponding 4- or 6-O-benzyl derivatives 12–16 in nearly quantitative yields (entries 2–6). Thus, the treatment of 7 with BH3

• ·Et2NH selectively provided 4-O-benzyl derivative 12 in quantitative yield (entry 2). The benzylidene group of glucosamine derivative 8 was also selectively cleaved under the microfluidic conditions by utilizing either Et3SiH or BH3·Et2NH as a hydride source to provide the 6- and 4-O-benzyl derivatives

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

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

• ), D-glucosamine 21 and carbamoyl phosphate (Scheme 4) [29][30][31][32]. The key intermediate, AHBA, is also a common precursor to other anticancer drugs, such as rifamycin and ansamycin. 2.2. Mode of action Mitomycins are quinone antitumor antibiotics that exert their biological activity through DNA