Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones

• Adesh Kumar Singh,
• Varsha Tiwari,
• Kunj Bihari Mishra,
• Surabhi Gupta and
• Jeyakumar Kandasamy

Beilstein J. Org. Chem. 2017, 13, 1139–1144, doi:10.3762/bjoc.13.113

• sulfone in 89% and 91%, respectively. Further, we have studied the oxidation of protected glucosamine thioglycoside (Table 2, entry 15) which provided 91% of sulfoxide and 82% of sulfone. The scope of the oxidation reaction was subsequently investigated with other monosaccharides such as galacto and

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• (i.e, AgNO3 or cetyltrimethylammonium bromide, CTAB), a control over the core morphology can be implemented with this methodology, as reported for the synthesis of mannose and galactose functionalized nanorods and nanostars [24] or glucosamine-coated nanostar AuNPs [22]. Respect to other methodologies

• vivo in immunocompetent healthy NMRI-mice and in humans [92]. The gold high X-ray absorption and a carbohydrate coating have been also exploited by Polito and co-workers to produce functional X-ray contrast agents based on glucosamine-coated AuNPs [22]. By micro-CT analysis performed on lung injured

Total synthesis of TMG-chitotriomycin based on an automated electrochemical assembly of a disaccharide building block

• Yuta Isoda,
• Norihiko Sasaki,
• Kei Kitamura,
• Shuji Takahashi,
• Sujit Manmode,
• Naoko Takeda-Okuda,
• Jun-ichi Tamura,
• Toshiki Nokami and
• Toshiyuki Itoh

Beilstein J. Org. Chem. 2017, 13, 919–924, doi:10.3762/bjoc.13.93

• electrochemical solution-phase synthesis developed by us. The synthesis of structurally well-defined TMG-chitotriomycin has been accomplished in 10-steps from a disaccharide building block. Keywords: automated synthesis; electrochemical oxidation; glycosylation; glucosamine; total synthesis; Introduction

• Degradation of chitin into oligoglucosamines and glucosamine is an important biological process and at least several enzymes such as chitinases and glucosaminidases are involved. Various types of inhibitors such as PUGNAc [1], nagastatin [2], NAG-thiazoline (NGT) [3], and pochonicine [4], have already been

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• of novel FCDs with improved properties. For example, simple monosaccharides such as glucose, glucosamine, mannose, fructose and their derivatives and common disaccharides, e.g., sucrose, lactose, and maltose have been employed to prepare fluorescent carbon dots (FCDs) using different methodologies

• -octadecene) that could subsequently be functionalised with hydrophilic PEG-diamine, providing an amine functionality for conjugation with glucosamine, histidine, arginine and folate. The yellow/red emissive loaded-CDs were shown to be viable bioimaging probes in live cells, since their emission did not

• , readily available neutral carbohydrate such as glucose as the carbon source in combination with a nitrogen-containing molecule. Glucosamine hydrochloride, which is a byproduct from the hydrolysis of chitosan and chitin polysaccharides found on crustacean shells, bears an amine functionality at C-2 and

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• negative controls. As positive control, we used chitosan (β-1,4 linked glucosamine) with average molecular weight, a fungal elicitor with known effect as NO and ROS inductor on A. thaliana [61]. Intracellular ROS was visualized using 2’,7’-dichlorodihydrofluorescein diacetate (H2DCF DA) as fluorescence

O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside

• Roman Sommer,
• Dirk Hauck,
• Annabelle Varrot,
• Anne Imberty,
• Markus Künzler and
• Alexander Titz

Beilstein J. Org. Chem. 2016, 12, 2828–2833, doi:10.3762/bjoc.12.282

• -glucosamine, have been described in rats as metabolites for detoxifying inorganic selenite intake [12][13]. Selenium-containing compounds are also widely used as tools for protein X-ray crystallography in structural biology. The determination of a protein structure depends on the correct phase recovering

Orthogonal protection of saccharide polyols through solvent-free one-pot sequences based on regioselective silylations

• Serena Traboni,
• Emiliano Bedini and
• Alfonso Iadonisi

Beilstein J. Org. Chem. 2016, 12, 2748–2756, doi:10.3762/bjoc.12.271

• ). The method proved also applicable to glucosamine hydrochloride, although in this case a higher excess of pyridine was needed for the conversion to occur (Scheme 1, reaction 2). Consistent with previous literature reports [68][69][70][71][72], silylation left unaltered the amino functionality which

Mutagenic activity of quaternary ammonium salt derivatives of carbohydrates

• Barbara Dmochowska,
• Karol Sikora,
• Anna Woziwodzka,
• Jacek Piosik and
• Beata Podgórska

Beilstein J. Org. Chem. 2016, 12, 1434–1439, doi:10.3762/bjoc.12.138

• . The polymers (oligosaccharides) of D-glucose found, for example, in wood (cellulose) and D-glucosamine present in shells of crabs and insects (chitin), are the widely known ones [1][2]. Another class of carbohydrate biopolymer derivatives – D-ribose and 2-deoxy-D-ribose – constitutes the backbone of

Synthesis and in vitro cytotoxicity of acetylated 3-fluoro, 4-fluoro and 3,4-difluoro analogs of D-glucosamine and D-galactosamine

• Štěpán Horník,
• Lucie Červenková Šťastná,
• Petra Cuřínová,
• Jan Sýkora,
• Kateřina Káňová,
• Roman Hrstka,
• Ivana Císařová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2016, 12, 750–759, doi:10.3762/bjoc.12.75

• Background: Derivatives of D-glucosamine and D-galactosamine represent an important family of the cell surface glycan components and their fluorinated analogs found use as metabolic inhibitors of complex glycan biosynthesis, or as probes for the study of protein–carbohydrate interactions. This work is

• focused on the synthesis of acetylated 3-deoxy-3-fluoro, 4-deoxy-4-fluoro and 3,4-dideoxy-3,4-difluoro analogs of D-glucosamine and D-galactosamine via 1,6-anhydrohexopyranose chemistry. Moreover, the cytotoxicity of the target compounds towards selected cancer cells is determined. Results: Introduction

• more than cisplatin and 5-fluorouracil (IC50 28 ± 3 μM and 54 ± 5 μM, respectively). Conclusion: A complete series of acetylated 3-fluoro, 4-fluoro and 3,4-difluoro analogs of D-glucosamine and D-galactosamine is now accessible by 1,6-anhydrohexopyranose chemistry. Intermediate fluorinated 1,6-anhydro

Self and directed assembly: people and molecules

• Tony D. James

Beilstein J. Org. Chem. 2016, 12, 391–405, doi:10.3762/bjoc.12.42

• electron transfer (PET) cation sensors developed by A. P. De Silva. (b) Fluorescence photoinduced electron transfer (PET) saccharide sensor. (c) Fluorescence AND logic sensors for D-glucosamine hydrochloride. (a) Pyrene diboronic acids (n = 3–8). (b) Pyrene monoboronic acid. (c) Block chart showing the

Mycothiol synthesis by an anomerization reaction through endocyclic cleavage

• Shino Manabe and
• Yukishige Ito

Beilstein J. Org. Chem. 2016, 12, 328–333, doi:10.3762/bjoc.12.35

• Streptomycetes [5][6][7][8][9][10]. It consists of an N-acetylcysteine, a D-glucosamine, and a D-myo-inositol moiety (Figure 1). D-Glucosamine is α-linked to D-myo-inositol at the 1-position, and N-acetylcysteine is linked to the amino group of D-glucosamine. The conformation of MSH has been investigated by NMR

• ]. After cleavage, the N-acetylcysteine S-conjugate is transported out of the cell, while the inositol–glucosamine conjugate is recycled to afford MSH. MSH also plays an important role in the growth and survival of Mycobacterium tuberculosis. Because MSH-dependent pathways are not found in eukaryotes, the

• stereochemistry of the glucosamine and cysteine moieties [21][22]. Hung also reported the utility of the 2-azido-2-deoxyglycosyl donor and resolved inositol isomers in a recent MSH synthesis [23]. Knapp et al. reported an intramolecular aglycone delivery method in order to achieve complete α-stereoselectivity [24

Spiro-fused carbohydrate oxazoline ligands: Synthesis and application as enantio-discrimination agents in asymmetric allylic alkylation

• Jochen Kraft,
• Martin Golkowski and
• Thomas Ziegler

Beilstein J. Org. Chem. 2016, 12, 166–171, doi:10.3762/bjoc.12.18

• stereo-differentiating potential of carbohydrate ligands in this type of reaction where their gluco-PHOX ligand, derived from glucosamine, resulted in a high enantiomeric excess of up to 98% [14]. Recently, Vidal et al. reported on a spiro-bis(isooxazoline) ligand A (Figure 1) [15] prepared via 1,3

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• singlet at δ = 7.78 ppm confirming the cycloaddition of derivatives 3 and 10. D-Glucosamine is an essential constituent of many naturally occurring oligosaccharides such as bacterial and fungal cell walls. Mainly, it is available as N-acetylglucosamine in β-glycosidic linkages (β-D-GlcNAc) [37

• ]. Chitinases are special enzymes involved in processing this valuable metabolite. Therefore, triazolocholesterol–glucopyranosylamine conjugates 16, 17 and 20 (Scheme 4) were prepared to compare the pharmacological effects of the modification of the D-glucopyranose moiety in VI (Figure 1) as glucosamine in

• carbon C-3 of the B ring of the lactose scaffold. On the other hand, modified cholesterols with a chalcone residue (6c), a hydroxyhexyl arm (11a), and NDMM protected glucosamine tag (16) showed low cytotoxicity as triazole 40. These conjugates showed IC50 values of 31.2, 27.1 and 30.3 μM, respectively

Synthesis and evaluation of the biostability and cell compatibility of novel conjugates of nucleobase, peptidic epitope, and saccharide

• Dan Yuan,
• Xuewen Du,
• Junfeng Shi,
• Ning Zhou,
• Abdulgader Ahmed Baoum,
• Khalid Omar Al Footy,
• Khadija Omar Badahdah and
• Bing Xu

Beilstein J. Org. Chem. 2015, 11, 1352–1359, doi:10.3762/bjoc.11.145

• conjugates 1–4, we chose thymine as the nucleobase, TTPV and LGFNI, which are two well-characterized peptide binding motifs [16], as the peptidic epitopes, and glucosamine as the saccharide. As a control, we changed the sequence of peptides to ETPV or EPTV. To investigate the function of the saccharide, we

• chain from the resin with 95% trifluoroacetic acid (TFA) without N-protecting groups. Later, NAS was obtained by reacting D-glucosamine hydrochloride with the fully protected NA. After cleaving the protecting group on amino acids with 95% TFA, we used reversed-phase high-performance liquid

• ) glucosamine, conjugates 1–8 are innocuous to HeLa cells for treatment of 3 days. Because of a longer doubling time of PC12 than HeLa cells [43][44], we incubated PC12 cells for 7 days. Conjugate 1–8 showed little toxicity to PC12 cells (Figure 5). The mixture of 5 + 8, which has the highest self-assembly

N-Alkyl derivatives of diosgenyl 2-amino-2-deoxy-β-D-glucopyranoside; synthesis and antimicrobial activity

• Agata Walczewska,
• Daria Grzywacz,
• Dorota Bednarczyk,
• Małgorzata Dawgul,
• Andrzej Nowacki,
• Wojciech Kamysz,
• Beata Liberek and
• Henryk Myszka

Beilstein J. Org. Chem. 2015, 11, 869–874, doi:10.3762/bjoc.11.97

• . Keywords: antimicrobial activities; D-glucosamine; diosgenin glycosylation; N-alkylation; Introduction Saponins are a group of steroid or triterpenoid glycosides, widely distributed in the plant kingdom [1]. Saponins are characteristic by their foaming properties in aqueous solution, causing them to be

• -hydroxy derivatives of D-glucose and L-rhamnose [49]. Glycosylation of diosgenin with twelve different derivatives of D-glucosamine (2a–d, 3a–d, and 5a–d), was examined using “normal” and “reverse” procedures [50] (Table 1). In the “normal” procedure, the promoter (silver triflate or trimethylsilyl

Synthesis and characterization of pH responsive D-glucosamine based molecular gelators

• Navneet Goyal,
• Hari P. R. Mangunuru,
• Bargav Parikh,
• Sonu Shrestha and
• Guijun Wang

Beilstein J. Org. Chem. 2014, 10, 3111–3121, doi:10.3762/bjoc.10.328

• for soft biomaterials. Low molecular weight hydrogelators are especially useful for exploring biomedical applications. Previously, we found that 4,6-O-benzylidene acetal protected D-glucose and D-glucosamine are well-suited as building blocks for the construction of low molecular weight gelators. To

• better understand the scope of D-glucosamine derivatives as gelators, we synthesized and screened a novel class of N-acetylglucosamine derivatives with a p-methoxybenzylidene acetal protective group. This modification did not exert a negative influence on the gelation. On the contrary, it actually

• naproxen from the pH responsive gels were also analyzed under acidic and neutral conditions. Our findings are useful for the design of novel triggered release self-assembling systems and can provide an insight into the influence of the the structure on gelation. Keywords: glucosamine; hydrogelators

Synthesis of aromatic glycoconjugates. Building blocks for the construction of combinatorial glycopeptide libraries

• Markus Nörrlinger and
• Thomas Ziegler

Beilstein J. Org. Chem. 2014, 10, 2453–2460, doi:10.3762/bjoc.10.256

• also previously used for the preparation of a similar t-butyl succinate of glucosamine [25]. Upon treatment with trifluoroacetic acid in dichloromethane, esters 11 were converted into the corresponding free acids 12 in 91–98% yield (Table 1). Finally, glycopeptide building blocks 1 and 2 were prepared

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions

• Anne-Katrin Späte,
• Verena F. Schart,
• Julia Häfner,
• Andrea Niederwieser,
• Thomas U. Mayer and
• Valentin Wittmann

Beilstein J. Org. Chem. 2014, 10, 2235–2242, doi:10.3762/bjoc.10.232

• higher fluorescence staining of cell-surface glycoconjugates, the glucosamine derivative gave higher labeling efficiency with protein preparations containing also intracellular proteins. Keywords: bioorthogonal chemistry; carbohydrates; cyclopropenes; inverse-electron-demand Diels-Alder reactions

• them well-accessible for labeling reactions [31]. However it has become of increasing interest to also investigate intracellular glycoproteins. We, thus, developed the glucosamine and galactosamine derivatives Ac4GlcNCyoc (1) and Ac4GalNCyoc (2) which are expected to be incorporated into O-GlcNAcylated

• carried out as described for the synthesis of Ac4ManNCyoc (3) [24]. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-((2-methylcycloprop-2-en-1-yl)methoxycarbonylamino)-D-glucopyranose (Ac4GlcNCyoc, 1). To a solution of glucosamine hydrochloride (5, 2 g, 9.2 mmol) in MeOH (20 mL) NaOMe (18 mL of a 0.5 M solution in MeOH

Design, automated synthesis and immunological evaluation of NOD2-ligand–antigen conjugates

• Marian M. J. H. P. Willems,
• Gijs G. Zom,
• Nico Meeuwenoord,
• Ferry A. Ossendorp,
• Herman S. Overkleeft,
• Gijsbert A. van der Marel,
• Jeroen D. C. Codée and
• Dmitri V. Filippov

Beilstein J. Org. Chem. 2014, 10, 1445–1453, doi:10.3762/bjoc.10.148

• attached to the anomeric center of the glucosamine moiety using oxazoline 6 [37][38][39]. Deacetylation and subsequent installation of the benzylidene protective group then gave alcohol 9. Coupling of 9 with (S)-2-chloropropanoic acid in the presence of sodium hydride resulted in the formation of protected

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• and chitosan derivatives for pharmaceutical applications was described [22]. Chitosan is the polysaccharide obtained from the abundant chitin by alkali or enzymatic degradation. It consists of a backbone of β-(1→4)-linked D-glucosamine units with a variable degree of N-acetylation. The protonated

• amino groups of chitosan favor interaction with negatively charged cellular surfaces. The amino groups of chitosan may be derivatized with PEG chains, thus modifying the physicochemical properties. Chitosan was first modified in the amino group of the glucosamine units with a PEG-aldehyde to yield an

• from N-phthaloylchitosan by etherification with poly(ethylene glycol) monomethyl ether (mPEG) iodide obtaining different degrees of O-substitution [56]. Several strategies were designed to obtain regioselective PEGylation at C-6 of the glucosamine unit [57]. Other methods of PEGylation included, among

Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7

• Pintu Kumar Mandal,
• Debashis Dhara and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2014, 10, 293–299, doi:10.3762/bjoc.10.26

• well-known role in interactions between plants and bacteria [16][17][18][19][20][21]. Recently, Sigida et al. reported the structure of the repeating unit of the LPS present in the cell wall of Azospirillum brasilense strain Sp7: a tetrasaccharide consisting of D-galactose, D-glucosamine, L-rhamnose

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

• 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

• , Amberlite IR-120 H+ (100 mL), 0 °C, water, 4 h. b) NH2OH·HCl, NaOAc, MeOH, rt, 6 h. c) H2, Pd/C (10%), 4.4% formic acid, MeOH, rt, 10 h. The initial polymer-supported nitrite set up. A solution of glucosamine hydrochloride was passed over the resin into a round bottom flask and then stirred with heating

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

• yielded 4,6-diol 16 in less than 30 minutes at room temperature. Disaccharide 16 was then regio- and stereoselectively glycosylated with N-Troc protected glucosamine donor 12 taking advantage of the higher reactivity of the primary OH at C-6 with respect to the C-4 OH group and trisaccharide 17 was

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

• containing D-glucosamine, L-rhamnose, D-glucose and D-galactofuranose moieties in a 1:1:1:1 ratio (Figure 1). The emergence of multi drug resistant bacterial strains forces medicinal chemists to develop new approaches to combat bacterial infections. Since the structure of the O-antigen influences the

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

• Mayeul Collot,
• Steffen Eller,
• Markus Weishaupt and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

• protecting group of the glucosamine was reduced under Staudinger conditions (Scheme 6, Supporting Information File 1). Therefore, imidate 34 was glycosylated to functionalized resin 23. In the next step the azide was reduced by using PMe3 under basic and aqueous conditions. The use of THF swelled the PS