Two antibacterial and PPARα/γ-agonistic unsaturated keto fatty acids from a coral-associated actinomycete of the genus Micrococcus

• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku,
• Nobuyasu Matsuura,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 297–304, doi:10.3762/bjoc.16.29

• natural products have been isolated from sponge-associated Micrococcus, including glycosylated glycerolipid [13][14], cyclic peptide [15], xanthone glycoside [16], and halogenated diphenyl ether [14]. Until now, however, no natural products are known from coral-associated Micrococcus. As a part of our

Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose

• Lukáš Kerner and
• Paul Kosma

Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2

• preliminary experiments, Lewis acid cleavage using BBr3, BCl3, and TiCl4, respectively, was not successful, although the latter reagent had previously been used to deprotect two benzyl groups from an allyl glycoside containing a 4-amino-4-deoxy-ʟ-arabinose residue [36]. Cleavage of the benzyl protecting

Two new aromatic polyketides from a sponge-derived Fusarium

• Mada Triandala Sibero,
• Tao Zhou,
• Keisuke Fukaya,
• Daisuke Urabe,
• Ocky K. Karna Radjasa,
• Agus Sabdono,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2019, 15, 2941–2947, doi:10.3762/bjoc.15.289

• metabolite of the fungus Geosmithia [24]. Plant metabolites, feralolide and its glycoside, possessing the same skeleton as 2 were reported from the medicinal herb Aloe vera [29], but this carbon skeleton is novel as a fungal secondary metabolite. Experimental General experimental procedures NMR spectra were

Chemical synthesis of the pentasaccharide repeating unit of the O-specific polysaccharide from Escherichia coli O132 in the form of its 2-aminoethyl glycoside

• Debasish Pal and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2019, 15, 2563–2568, doi:10.3762/bjoc.15.249

• from E. coli O132 is accomplished in the form of its 2-aminoethyl glycoside. The 2-aminoethyl glycoside is particularly important as it allows further glycoconjugate formation utilizing the terminal amine without affecting the stereochemistry of the reducing end. The target was achieved through a [3

• glycoside; diarrhea; galactofuranose; O-specific polysaccharide; total synthesis; Introduction O-Polysaccharides are the most complex molecular systems present in the bacterial cell wall owing to the presence of various sugar residues connected through diverse glycosidic linkages. These complex structures

• and Galf. In this communication we report on the total synthesis of this pentasaccharide repeating unit of the O-specific polysaccharide in the form of its 2-aminoethyl glycoside (Figure 1) through a [3 + 2] converging strategy. The building blocks were prepared by suitable protecting group

Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside

• Dimitri Fayolle,
• Nathalie Berthet,
• Bastien Doumeche,
• Olivier Renaudet,
• Peter Strazewski and
• Michele Fiore

Beilstein J. Org. Chem. 2019, 15, 937–946, doi:10.3762/bjoc.15.90

• Fisher reaction between pyranoses and fatty alcohols of different lengths [8][9]. Alkyl thioglycosides are known for their properties as co-surfactants [10] and present interesting antimicrobial activities [11], acting as glycosidase inhibitors and being resistant towards glycoside hydrolases [12][13

Synthesis of the aglycon of scorzodihydrostilbenes B and D

• Katja Weimann and
• Manfred Braun

Beilstein J. Org. Chem. 2019, 15, 610–616, doi:10.3762/bjoc.15.56

• brine and dried with magnesium sulfate. The solvent was removed in a rotary evaporator and the crude product (1.08 g) was purified by column chromatography (silica gel; ethyl acetate/n-hexane, 1:4 to 1:2) to give 91 mg (14%) of pure glycoside 12 as a colorless syrup. 1H NMR (CDCl3, 600 MHz) δ 2.04 (s

• -catalyzed addition of ketones 6 to styrenes 7. Yields: 8a: 65%; 8b: 68%; 8c: 73%; 8d: 40%. Cleavage of benzyl protecting groups in ketones 8a and 8b. Synthesis of scorzodihydrostilbene aglycon 9. Synthesis of glycoside 12 and deprotected epi-scorzodihydrostilbene D (13). Yields of isolated products: 12: 14

Low-budget 3D-printed equipment for continuous flow reactions

• Jochen M. Neumaier,
• Amiera Madani,
• Thomas Klein and
• Thomas Ziegler

Beilstein J. Org. Chem. 2019, 15, 558–566, doi:10.3762/bjoc.15.50

• results for the synthesis of methyl glycoside 3 were obtained using an overall flow rate of 200 μL/min leading to a residence time of 5 min and a yield of 44%. A similar Koenigs–Knorr type glycosylation under continuous flow has only been described previously for glucuronidation of bile acids [36

• ]. Unfortunately, the synthetic steps for the glycoside preparation could not be combined in a multistep reaction, due to clogging of the packed bed reactor, most likely due to the formation of silver bromide during the Koenigs–Knorr reaction. No such clogging was observed when the column was packed with Fetizon’s

• synthesis of acetobromo-α-D-glucose 2. b) Photograph of a typical setting for continuous flow reaction. Preparation of acetobromo-α-D-glucose 2. Flow Koenigs–Knorr reaction to methyl glycoside 3 with silver triflate. Preparation of glycosyl donor 5. Two-step glycosylation reactions starting from pyranose 3

Convergent synthesis of the pentasaccharide repeating unit of the biofilms produced by Klebsiella pneumoniae

• Arin Gucchait,
• Angana Ghosh and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2019, 15, 431–436, doi:10.3762/bjoc.15.37

• the biofilm producing polysaccharide secreted by K. pneumoniae. A convergent synthesis of a pentasaccharide as its 2-aminoethyl glycoside containing a β-D-mannosidic moiety and a α-D-glucuronic acid moiety is presented herein. The presence of a 2-aminoethyl group at the reducing end of the

• pentasaccharide may provide ready availability of an amino functionality to expedite the conjugation of the pentasaccharide with an appropriate protein without affecting the sugar rings in the molecule [12][13]. Results and Discussion The target pentasaccharide as its 2-aminoethyl glycoside 1 was synthesized

• reaction conditions furnished the D-glucuronic acid containing pentasaccharide derivative, which on global deprotection under hydrogenolysis in the presence of Pearlman’s catalyst [40] afforded the target pentasaccharide as its 2-aminoethyl glycoside 1 in 61% yield (Scheme 4). Conclusion In summary, a

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

•  4). The reaction between Nam (1a) and 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose (2a) in acetonitrile at room temperature resulted in the corresponding triacetate derivative of NR+ triflate (OTf−) 9a which was converted without isolation into NR+OTf− by methanolysis. The final N-glycoside contained 13

Unexpected loss of stereoselectivity in glycosylation reactions during the synthesis of chondroitin sulfate oligosaccharides

• Teresa Mena-Barragán,
• José L. de Paz and
• Pedro M. Nieto

Beilstein J. Org. Chem. 2019, 15, 137–144, doi:10.3762/bjoc.15.14

• DBU. The glycosylation reaction with 2-propanol using TMSOTf as Lewis acid at 0 ºC cleanly provided the β-isopropyl glycoside 13 in 65% yield. Interestingly, no α-anomer was detected in the reaction mixture. Finally, cleavage of the levulinyl group using hydrazine monohydrate in pyridine/acetic acid

Lectins of Mycobacterium tuberculosis – rarely studied proteins

• Katharina Kolbe,
• Sri Kumar Veleti,
• Norbert Reiling and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2019, 15, 1–15, doi:10.3762/bjoc.15.1

• glycocalyx is a major determinant of cell type, function, and developmental state, and can have serious pathogenic consequences in the event of dysregulation [43]. The glycoside composition of the mycobacterial cell wall differs strongly from the glycocalyx of eukaryotic cells (Figure 2). The bacterial cell

• polysaccharide mannan, composed of linear α(1→6)-linked, and α(1→2)- and α(1→3)-branched mannopyranosides, and the glycoside p-nitrophenyl α-D-mannopyranoside showed even higher hemagglutination inhibitory potency. These initial experiments let to the assumptions that mycotin is a secreted D-arabinoside- and α-D

• -mannopyranoside-binding lectin [72]. The relatively high glycoside concentrations (in the mM range) used in this hemagglutination inhibition assays; however, indicate that the tested mono- and polysaccharides are not the optimal or native ligands for this lectin. Other mycobacteria, like Mtb, have since been

Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step

• Pierre-Antoine Nocquet,
• Aurélie Macé,
• Frédéric Legros,
• Jacques Lebreton,
• Gilles Dujardin,
• Sylvain Collet,
• Arnaud Martel,
• Bertrand Carboni and
• François Carreaux

Beilstein J. Org. Chem. 2018, 14, 2949–2955, doi:10.3762/bjoc.14.274

• structures 3-amino-2-deoxy sugars [1]. For instance, N,N-dimethyl-L-vancosamine is an essential component of pluramycin antibiotics such as kidamycin and pluramycin A via a C-glycosidic linkage (Figure 1). For constructing aryl C-glycoside bonds, glycal derivatives are versatile synthetic intermediates

Pathoblockers or antivirulence drugs as a new option for the treatment of bacterial infections

• Matthew B. Calvert,
• Varsha R. Jumde and
• Alexander Titz

Beilstein J. Org. Chem. 2018, 14, 2607–2617, doi:10.3762/bjoc.14.239

• these compounds showed superior thermodynamics and kinetics of binding to LecB compared to mannose, resulting in a prolonged receptor residence time of several minutes [48]. In a complementary approach, glycomimetic C-glycoside 17 was obtained, aiming at improved metabolic stability and selectivity [49

Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues

• Kai Zhang,
• Jiarong Li,
• Honglin Liu,
• Haiyou Wang and
• Lamusi A

Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207

• ether bond at the C17 position under acidic conditions. Synthesis of spinetoram J analogues All carbohydrates and alcohols were activated by CNCCl3 with DBU as catalyst initially to afford glycoside donors, and then the 17-pseudoaglycone of spinetoram J was glycosylated with donors in the presence of

• BF3·(C2H5)2O under Ar gas. Due to the high yields and few byproducts in the synthesis of glycoside donors, the donors could be used directly in the glycosylation without purification. Insecticidal activity The insecticidal activities of synthetic spinetoram J and its analogues were evaluated using

Synthesis of 1,4-imino-L-lyxitols modified at C-5 and their evaluation as inhibitors of GH38 α-mannosidases

• Maroš Bella,
• Sergej Šesták,
• Ján Moncoľ,
• Miroslav Koóš and
• Monika Poláková

Beilstein J. Org. Chem. 2018, 14, 2156–2162, doi:10.3762/bjoc.14.189

• , indolizidines etc. which exhibited remarkable biological activities and are highly interesting as pharmaceutical agents [15][16][17][18][19]. In addition, iminosugars exhibited a powerful inhibitory activity against a wide range of glycoside hydrolases [20][21][22]. One naturally occurring iminosugar, alkaloid

• swainsonine, interferes with the glycosylation pathway where it specifically inhibits GH38 glycoside hydrolases [23][24]. Up to date, swainsonine is the most potent Golgi mannosidase II (GMII) inhibitor. It is known that inhibition of the biosynthesis of complex N-glycans in the Golgi apparatus influences

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• spirocyclic glycoside that was launched as antidiabetic agent in 2012 in Japan [15]. Rolapitant (5) is a marketed drug that was approved in 2015 for the treatment of nausea and vomiting [16]. Compound 6 is a spiropyrimidinetrione analogue which is currently in clinical trials for the treatment of gonorrhea

Anomeric modification of carbohydrates using the Mitsunobu reaction

• Julia Hain,
• Patrick Rollin,
• Werner Klaffke and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1619–1636, doi:10.3762/bjoc.14.138

• achieve good results in the Mitsunobu procedure. We have reviewed on the one hand the literature on anomeric esterification, including glycosyl phosphates, and on the other hand glycoside synthesis, including S- and N-glycosides. The mechanistic details of the Mitsunobu reaction are discussed as well as

• circumstances. Keywords: anomeric stereoselectivity; carbohydrates; glycoside synthesis; Mitsunobu reaction; Introduction Fifty years ago, Oyo Mitsunobu reported a preparation of esters from alcohols and carboxylic acids supported by two auxiliary reagents, diethyl azodicarboxylate (DEAD) and

• outcome of the reaction towards β-configured products [53]. In this case, phenolic chromium tricarbonyl complexes of weaker acids such as p-cresol were employed to improve the yield. The challenge of glycoside synthesis using sugars devoid of a C-2 participating group is also highlighted by a total

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• , Tokushima, 770-8505, Japan 10.3762/bjoc.14.137 Abstract To synthesize nucleoside and oligosaccharide derivatives, we often use a glycosylation reaction to form a glycoside bond. Coupling reactions between a nucleobase and a sugar donor in the former case, and the reaction between an acceptor and a sugar

• glycoside bond. In the case of nucleoside synthesis, a coupling reaction between a persilylated nucleobase and a sugar donor is typically used [15][16][17]. On the other hand, the reaction between an acceptor and sugar donor is carried out in the presence of an appropriate activator for oligosaccharide

• the hypervalent iodine-mediated oxidative reactions with theses derivatives provide a different method to build glycosidic bonds. Diversity in glycoside bond forming reactions would contribute to improve the oligosaccharide synthesis. Conclusion The Pummerer-type glycosylation includes oxidation of a

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

AuBr₃-catalyzed azidation of per-O-acetylated and per-O-benzoylated sugars

• Jayashree Rajput,
• Srinivas Hotha and
• Madhuri Vangala

Beilstein J. Org. Chem. 2018, 14, 682–687, doi:10.3762/bjoc.14.56

• -benzoylated disaccharides needed 2–3 h of heating at 55 °C. Keywords: acylated sugars; azidation; gold(III) bromide; N-glycoside; oxophilicity; Introduction The past few decades had seen the enrichment of transition metal complexes in various glycosylation strategies [1]. In particular, gold complexes with

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• types of protecting groups – allyloxycarbonyl (Alloc), hexyldimethylsilyl (TDS) and benzyl – were sequentially removed to provide the target compound 58. A monophosphoryl lipid A analogue 59 wherein the anomeric center of the proximal GlcN moiety is modified as methyl glycoside was prepared in a similar

• methyl glycoside 59 showed somewhat higher pro-inflammatory activity. Interestingly, attachment of varying 3-O-substitutions at position 3 of the reducing GlcN moiety in MPLA analogue 60 did not enhance the adjuvant activity [107]. Importantly, synthetic MPLA derivatives having variable acylation pattern

Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

• Vivek Poonthiyil,
• Thisbe K. Lindhorst,
• Vladimir B. Golovko and
• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2

• , oligosaccharides usually bind lectins in a multivalent cooperative fashion. This avidity is significantly greater than the sum of the individual monomeric carbohydrate–protein interactions, and is sometimes referred to as the ‘cluster glycoside’ effect [6]. In order to study biological processes that involve these

Electron-deficient pyridinium salts/thiourea cooperative catalyzed O-glycosylation via activation of O-glycosyl trichloroacetimidate donors

• Mukta Shaw,
• Yogesh Kumar,
• Rima Thakur and
• Amit Kumar

Beilstein J. Org. Chem. 2017, 13, 2385–2395, doi:10.3762/bjoc.13.236

• , the optimized method is also utilized for the regioselective O-glycosylation by using a partially protected acceptor. Keywords: cooperative catalysis; electron-deficient pyridinium salts; O-glycoside; regioselectivity; thiourea; Introduction The glycosidic linkage is the principal bond present in a

• with phosphorus acids) for stereoselective O-glycoside bond formation [30]. Similarly, Galan et al. reported a method for the preparation of 2-deoxyglycosides from glycals under the influence of cooperative catalysis (chiral phosphoric acids/thiourea derivatives) [31]. Encouraged by these reports and

• acceptor 2a in 1:1.1 molar ratio with 10 mol % of 3a in dry DCM at room temperature, the desired O-glycoside 5a was isolated in 56% yield and with poor selectivity (Table 1, entry 2). The use of 25 mol % of 3a was required to drive the reaction to completion with 86% yield (Table 1, entry 3). This result

Diosgenyl 2-amino-2-deoxy-β-D-galactopyranoside: synthesis, derivatives and antimicrobial activity

• Henryk Myszka,
• Patrycja Sokołowska,
• Agnieszka Cieślińska,
• Andrzej Nowacki,
• Maciej Jaśkiewicz,
• Wojciech Kamysz and
• Beata Liberek

Beilstein J. Org. Chem. 2017, 13, 2310–2315, doi:10.3762/bjoc.13.227

• the β anomer). Glycosylation of diosgenin with 2 was performed in dichloromethane by a “reverse” procedure: The glycosyl donor was added to the solution of diosgenin and the promoter (silver triflate) [31]. This procedure afforded the expected β glycoside 3 in 80% yield. The structure of 3 was

An efficient synthesis of a C₁₂-higher sugar aminoalditol

• Łukasz Szyszka,
• Anna Osuch-Kwiatkowska,
• Mykhaylo A. Potopnyk and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2017, 13, 2146–2152, doi:10.3762/bjoc.13.213

• ; Anal. calcd for C76H79N3O11: C, 75.41; H, 6.58; N, 3.47; found: C, 75.41; H, 6.47; N, 3.34. Acetolysis of glycoside 4; synthesis of 5 Azide 4 (0.36 g, 0.3 mmol) was dissolved in ethyl acetate (2.3 mL) to which acetic anhydride (4.6 mL) and sulfuric acid (0.72 mL of the solution: conc. H2SO4 (0.05 mL