Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

• Martyn Jevric,
• Julian Klepp,
• Johannes Puschnig,
• Oscar Lamb,
• Christopher J. Sumby and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

• reports of Karban et al. (Scheme 2) [19]. We envisaged that these hexose-derived building blocks with a 2,5-anhydro bond such as 5 could be useful materials for the construction of C-nucleosides such as formycin A (Figure 1) [22][23][24]. The preparation of C-glycosides usually involves the creation of

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• for the synthesis of O- [4][34][35] and C-glycosides [36] and by employing more reactive armed [1] glycosyl fluorides. In glycosylation reactions the solvent plays a critical role in terms of stabilizing the oxocarbenium ion intermediate and/or affecting the α,β-selectivity [1]. In 2017, Matheu et al

• -derived glycosyl fluorides, and novel conditions have been successfully applied for the synthesis of O-, S- and C-glycosides in moderate to excellent yields. The glycosylation in liquid SO2 is proposed to proceed via a solvent-separated ion pair and with stereoselectivity that is substrate-controlled and

• halides α-1a–c gave O-mannoside 3a as the major product in 58 to 71% yield, while overall yield of products 3a,c varied from 77% for α-1b to quant. for α-1a (Table S1, Supporting Information File 1). Pivaloyl-protected mannosyl fluoride α-1a was further applied for the synthesis of various O-, S- and C

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• fullerene ligands 66–68. Synthesis of C60-attached SCS pincer–palladium(II) complex 70. Synthesis of spiro-linked C-glycosides of fullerenes 71 and 72. Synthesis of quinone-substituted methanofullerene derivatives 76–78. Synthesis of spiroannelated methanofullerenes 79–81. The synthetic route for

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

• , followed by iodination and phosphonate introduction by an Arbusov reaction. Alternative approaches were elaborated from olefinic C-glycosides, which were converted into the corresponding C-linked hydroxymethyl derivatives and processed to give the glycosyl methylphosphonic acid derivatives [18][19]. As the

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

• adhesion in mice [18][19]. These compounds have been extensively optimized in many works published by both groups, culminating in the identification of mannophosphates as prodrugs to increase oral bioavailability [20] and mannose C-glycosides, such as compound 6 , demonstrating enhanced in vivo metabolic

Enzymatic synthesis of glycosides: from natural O- and N-glycosides to rare C- and S-glycosides

• Jihen Ati,
• Pierre Lafite and
• Richard Daniellou

Beilstein J. Org. Chem. 2017, 13, 1857–1865, doi:10.3762/bjoc.13.180

• ]. More recently, BcGT1 from Bacillus subtilis was shown to efficiently catalyse the glucosylation of thiol-containing acceptors [32]. C-Glycosyltransferases For more than 50 years, C-glycosides have been identified in plants [33][34] as secondary metabolites. At least 5 families of aromatic aglycones

• chemoenzymatic syntheses of C-glycosides were described in other publications [40][49][50][51]. In all described C-GTs, the aglycone acceptor was found to be a derivative of polyhydroxybenzaldehyde, that exhibit an acidic carbon on the aromatic ring. Depending on the nature of the substrate and the C-GT involved

• thiofuranosides [76]. C-Glycosides synthesis There is no example of C-glycoside synthesis promoted by GHs reported in the literature so far, although as depicted by the mechanism, this kind of biocatalysed reaction can be envisioned. Conclusion To conclude, the enzymatic mechanisms that rule the activities of GTs

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• rationale remains elusive. To demonstrate that their conditions were viable in the presence of other hydroxy groups on the saccharides a small series of phenyl C-glycosides were synthesized (Table 5). In all cases the reaction was high yielding and perfectly stereospecific for both anomers even in the

• absence of a C2–OH group (Table 5, entries 5 and 6). The remarkable stereospecificity of this reaction coupled with its ability to provide C-glycosides, a class of compounds important in natural products [66] and drug design [67], makes this methodology a very powerful one. One very clear drawback

Aqueous semisynthesis of C-glycoside glycamines from agarose

• Juliana C. Cunico Dallagnol,
• Alexandre Orsato,
• Diogo R. B. Ducatti,
• Miguel D. Noseda,
• Maria Eugênia R. Duarte and
• Alan G. Gonçalves

Beilstein J. Org. Chem. 2017, 13, 1222–1229, doi:10.3762/bjoc.13.121

• . The unpolymerized product shows AnGal as a C-threofuranose motif [7] (see agarobiose, 2, Scheme 1) and because C-glycosides are useful moieties for chemical synthesis and medicinal chemistry, agarose hydrolysis products can be considered interesting carbohydrate-based building blocks [8] to be

Synthesis of D-manno-heptulose via a cascade aldol/hemiketalization reaction

• Yan Chen,
• Xiaoman Wang,
• Junchang Wang and
• You Yang

Beilstein J. Org. Chem. 2017, 13, 795–799, doi:10.3762/bjoc.13.79

• evaluation of carbohydrate–lectin interactions by conjugation with fluorescent quantum dots via click chemistry [13][14]. Besides, differentially protected D-manno-heptulose building blocks could serve as valuable precursors for the synthesis of C-glycosides [15][16]. The known synthesis of D-manno-heptulose

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

• Mikael Bols and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12

• C-glycosides it has been possible to obtain conformationally derived stereocontrol so that persilylated donors adopting a 1C4 conformation give the β-products. However, for O-glycosylation, this type of selectivity has been difficult to achieve. Some very useful stereoselectivities are obtained with

Diastereoselective synthesis of 3,4-dihydro-2H-pyran-4-carboxamides through an unusual regiospecific quasi-hydrolysis of a cyano group

• Mikhail Yu. Ievlev,
• Oleg V. Ershov,
• Mikhail Yu. Belikov,
• Angelina G. Milovidova,
• Viktor A. Tafeenko and
• Oleg E. Nasakin

Beilstein J. Org. Chem. 2016, 12, 2093–2098, doi:10.3762/bjoc.12.198

• influenza caused by influenza A and B viruses contain a 3,4-dihydro-2H-pyran fragment [5]. Moreover, dihydropyrans have been proven to be particularly useful in the preparation of cyclic components of macrocyclic antibiotics [6][7] and as precursors in the synthesis of C-glycosides [8]. Modern and

Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes

• Ivan Šnajdr,
• Kamil Parkan,
• Filip Hessler and
• Martin Kotora

Beilstein J. Org. Chem. 2015, 11, 1392–1397, doi:10.3762/bjoc.11.150

• ClCH2CH2Cl the latter required the presence of CuI in CH2Cl2 to achieve good yields of the products. A simple method for the preparation of α- and β-vinyl C-deoxyribosides was also developed. In addition, feasibility of deprotection and further transformations were briefly explored. Keywords: C-glycosides

• (8) There have been, to the best of our knowledge, just a handful of reports of cross-metathesis reactions of other vinyl C-glycosides. Among these reports metatheses of 1-(D-glucopyranosyl)prop-2-ene derivatives with various alkenes [36][37][38][39][40] and one report regarding a 1-(α-D

Synthesis of 1,2-cis-2-C-branched aryl-C-glucosides via desulfurization of carbohydrate based hemithioacetals

• Henok H. Kinfe,
• Fanuel M. Mebrahtu,
• Mandlenkosi M. Manana,
• Kagiso Madumo and
• Mokela S. Sokamisa

Beilstein J. Org. Chem. 2015, 11, 583–588, doi:10.3762/bjoc.11.64

• stereospecific preparation of 2,3-unsaturated-aryl-C-glycosides (Ferrier products). Keywords: aryl-C-glucoside; desulfurization; Ferrier product; hemithioacetal; Introduction 1-C (C-glycosides) and 2-C-branched carbohydrates are important carbohydrate analogues which have found wide application in

• glycochemistry and medicinal chemistry [1][2][3][4][5]. C-Glycosides, especially aryl-C-glycosides, are the main structural features of a number of biologically active natural products such as pluramycins (antibacterial and antitumor activities), angucyclines (antibacterial, antitumor activities, and inhibitors

• of oxidative enzymes), and benzoisochromanequinones (antibacterial, antitumor and antiplatelet aggregation activities) [2]. Moreover, the stability of the C–C glycosidic bond in C-glycosides provides the potential to serve as inhibitors of carbohydrate degrading enzymes [1][2][3][4][5]. Owing to

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions

• Bichlien H. Nguyen,
• Robert J. Perkins,
• Jake A. Smith and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2015, 11, 280–287, doi:10.3762/bjoc.11.32

• , commercially available, photovoltaic cell. Electrochemical recycling of a chemical oxidant. Examples of solar-driven direct electrochemical oxidations. Overoxidation of dithioketal. Examples of solar-driven, indirect electrochemical oxidations. Solar-driven synthesis of C-glycosides. Solar-driven oxidative

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

• Shekaraiah Devari,
• Manjeet Kumar,
• Ramesh Deshidi,
• Masood Rizvi and
• Bhahwal Ali Shah

Beilstein J. Org. Chem. 2014, 10, 2649–2653, doi:10.3762/bjoc.10.277

• , India 10.3762/bjoc.10.277 Abstract A novel metal-free strategy for a rapid and α-selctive C-alkynylation of glycals was developed. The reaction utilizes TMSOTf as a promoter to generate in situ trimethylsilylacetylene for C-alkynylation. Thanks to this methodology, we can access C-glycosides in a

• single step from a variety of acetylenes , i.e., arylacetylenes and most importantly aliphatic alkynes. Keywords: α-selective; C-alkynylation; glycal; metal free; TMSOTf; Introduction C-Glycosides represent an important class of carbohydrate mimics, owing to their presence in a large number of

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• debromination. The debenzylation and the N–O bond cleavage occur as next steps. Under these improved conditions the isomeric bicyclic 1,2-oxazine 15b was converted into aminopyran 17b in a good yield of 77%. The formed aminopyrans 17a and 17b can be regarded as amino C-glycosides. Compound 17a is related to

• involved in different diseases such as cancer [4], inflammation [5], and infections [6]. However, the use of carbohydrates as drugs has been strongly limited due to the hydrolytic lability of the glycosidic bond [7] and the weak binding affinities of single molecules. With the development of artificial C

• -glycosides which possess structural and functional aspects of the corresponding carbohydrates, these disadvantages can be overcome, resulting in an improved bioavailability, higher affinities and improved selectivities [8][9][10][11][12][13]. Recent results indicate that divalent rigid carbohydrate

Efficient carbon-Ferrier rearrangement on glycals mediated by ceric ammonium nitrate: Application to the synthesis of 2-deoxy-2-amino-C-glycoside

• Alafia A. Ansari,
• Y. Suman Reddy and
• Yashwant D. Vankar

Beilstein J. Org. Chem. 2014, 10, 300–306, doi:10.3762/bjoc.10.27

• -glycosides; carbon-Ferrier rearrangement; ceric ammonium nitrate; 2-deoxy-2-aminoglycosides; Overman rearrangement; Introduction The growing significance of C-glycosides can be attributed to their potential use as inhibitors of carbohydrate-processing enzymes [1][2][3], their extraordinary stability

• compared to O-glycosides, and their widespread applicability as intermediates in the synthesis of biologically important molecules [4][5][6][7][8]. C-glycosides are also subunits of several biologically active natural products [9][10][11]. Consequently, numerous reports are available in literature on the

• synthesis of C-glycosides [12][13][14]. Among these, the Ferrier rearrangement [15] of glycals with protic acids [5][16][17] or Lewis acids [18][19][20][21][22] and carbon nucleophiles such as allylsilanes [23], silylacetylenes [24], silyl enol ethers [25], olefins [26], and organozinc reagents [27] has

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

• 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

• benzyl O-, N-, S- and C-glycosides. Results and Discussion Preparation of η6-tricarbonylchromium complexes of glycosides In general, tricarbonyl(η6-arene)chromium compounds can be prepared in a wide variety of methods [4]. However, the following two methods are the most commonly employed ones: (a) ligand

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

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

Synthesis of glycosylated β³-homo-threonine conjugates for mucin-like glycopeptide antigen analogues

• Florian Karch and
• Anja Hoffmann-Röder

Beilstein J. Org. Chem. 2010, 6, No. 47, doi:10.3762/bjoc.6.47

• instance, stable TACA mimics comprising C-glycosides [11][12][13][14], S-glycosides [15][16][17][18][19] and deoxyfluoro sugars [20] have been used to circumvent hydrolytic degradation by endogenous glycosidases. In principle, antigenicity of the artificial TACA derivatives should be enhanced by minor