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

• current enzymatic methods described for the synthesis of unusual C- and S-glycosidic linkages, their mechanisms and the corresponding perspectives. Review Glycosyltransferases Glycosyltransferases (GTs, E.C. 2.4.1.x) catalyse the addition of a glycosyl moiety to an acceptor, using an activated sugar as

• sugar during GT-catalysed reactions, GTs are also classified as inverting or retaining (Figure 1). Inverting GTs operate via a SN2 mechanism in a single displacement step where an acid/base residue enhances the nucleophilicity of the acceptor, via an oxocarbenium-like transition state. Unlike inverting

• aggression. Their biosynthetic pathway requires the action of a S-GT (UGT74B1) that catalyses the reaction between a thiohydroximate acceptor and UDP-α-D-glucose as sugar donor to yield the corresponding desulfoglucosinolate (Figure 2) [20][21]. UGT74B1 from A. thaliana is a versatile enzyme in terms of

Effect of uridine protecting groups on the diastereoselectivity of uridine-derived aldehyde 5’-alkynylation

• Raja Ben Othman,
• Mickaël J. Fer,
• Laurent Le Corre,
• Sandrine Calvet-Vitale and
• Christine Gravier-Pelletier

Beilstein J. Org. Chem. 2017, 13, 1533–1541, doi:10.3762/bjoc.13.153

• sugar moiety [6]. Many of them concern the C-2’ and C-3’ sugar positions. However, functionalization at C-5’ has been much less reported, particularly the stereocontrolled formation of a stereogenic center at C-5’, in spite of its important role for biological activity (Figure 1) [16][17][18][19]. In

2-Methyl-2,4-pentanediol (MPD) boosts as detergent-substitute the performance of ß-barrel hybrid catalyst for phenylacetylene polymerization

• Julia Kinzel,
• Daniel F. Sauer,
• Marco Bocola,
• Marcus Arlt,
• Tayebeh Mirzaei Garakani,
• Andreas Thiel,
• Klaus Beckerle,
• Tino Polen,
• Jun Okuda and
• Ulrich Schwaneberg

Beilstein J. Org. Chem. 2017, 13, 1498–1506, doi:10.3762/bjoc.13.148

• membrane of Escherichia coli (E. coli) [30]. For extraction of membrane proteins, commonly micelle-forming detergents such as sodium dodecyl sulfate (SDS), polyethylene–polyethyleneglycol (PE–PEG), sugar glycosides or polyoxyethylenes are applied [24][25][28][31][32]. SDS is an efficient detergent for

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

• 1-O-phosphofuranosyl hexoses in good to excellent yield (Table 1, entries 1–4) [43]. The conditions provided only a very modest stereoselectivity, however, the α anomer was slightly favored regardless of the stereochemistry of the sugar at C2. Most importantly, very little or no ring expansion to

• 1,6-anhydrosugars: The treatment of a 2-deoxy-2-N-acetylated sugar with DMC and an amine base in the absence of any nucleophile provides the observable (by 1H NMR) or even isolatable (LacNAc) corresponding oxazoline derivative in moderate to very good yield (Scheme 21, pathway A) [68][69]. It is

• transformations as well. Under the same conditions but using a C2–OH sugar, the corresponding isolatable 1,6-anhydrosaccharide is formed in good to excellent yield [71]. The authors proposed as the intermediate species the unstable 1,2-anhydrosaccharide resulting from nucleophilic displacement of the activated

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

• -anhydro-α-L-galactopyranose unit (naturally present in the agarose structure) to all glycamines synthesized, constituting an amino-substituted C-threofuranoside moiety, which is closely related to (+)-muscarine. Keywords: amino sugar; 3,6-anhydro-α-L-galactopyranose; polysaccharide (agar); protecting

• exchange resin, which by eliminating acetate ions enabled the elimination of remaining ammonia by reduced pressure evaporation. The amino sugar rich fraction was then concentrated and chromatographed on silica gel using MeOH/2 M NH4OH as mobile phase. An aqueous solution containing the isolated free-base

• ). By performing the reductive amination between 2 and dimethylamine hydrochloride we obtained a mixture of epimers (8 and epi-8) which differed on the stereochemistry of the C-2 of the 3,6-anhydro amino sugar moiety. This was related to the fact that during the course of the reductive amination, the

Sugar-based micro/mesoporous hypercross-linked polymers with in situ embedded silver nanoparticles for catalytic reduction

• Qing Yin,
• Qi Chen,
• Li-Can Lu and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 1212–1221, doi:10.3762/bjoc.13.120

• reduction of 4-nitrophenol (4-NP) with an activity factor ka = 51.4 s−1 g−1, which is higher than some reported AgNP-containing composite materials. Keywords: catalytic reduction; hypercross-linking; porous polymers; silver nanoparticles; sugar; Introduction Hypercross-linked polymers (HCPs) are

• ]. The chemical structure of monosaccharides is commonly a polyhydroxylated aldehyde or ketone with a pyranose ring structure. These hydroxy groups can be easily benzylated to afford sugar-based monomers containing multiple aromatic skeletons. Recently, Liu and Dai have reported a class of novel

• molecules into the holes with the catalyst active sites [38][39]. Therefore, it is of great interest to improve the catalytic efficiency by encapsulating the nanocatalyst in a porous organic polymer. Keeping these issues in mind, three novel sugar-based porous organic polymers SugPOP-1–3 were designed and

Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

• Serge Pérez and
• Daniele de Sanctis

Beilstein J. Org. Chem. 2017, 13, 1145–1167, doi:10.3762/bjoc.13.114

• distortion and particular caution should be given to crystallographic reports where there is a wrong linkage distance specification or a mistaken anomer and handedness. Automated detection, building and validation of sugar models starting from X-ray diffraction data are being implemented [34]. Carbohydrate

• the biosynthesis of glycosidic linkage requires the transfer of a sugar residue from a donor to an acceptor [35]. Acceptor substrates are carbohydrates, proteins, lipids, DNA, flavonol, antibiotics and steroids. In contrast, glycosyl donor substrates are mostly sugar nucleotides, such as UDP-GlcNAc

• . Initially CBMs were classified as a cellulose-binding domain, but their occurrence in other carbohydrate active enzymes required a dedicated classification, separate from other non-catalytic proteins, and similiar to lectins, antibodies and sugar-transport molecules. Depositions in the PDB for CBMs amount

An eco-compatible strategy for the diversity-oriented synthesis of macrocycles exploiting carbohydrate-derived building blocks

• Sushil K. Maurya and
• Rohit Rana

Beilstein J. Org. Chem. 2017, 13, 1106–1118, doi:10.3762/bjoc.13.110

• , Himachal Pradesh, 176 061, India 10.3762/bjoc.13.110 Abstract An efficient, eco-compatible diversity-oriented synthesis (DOS) approach for the generation of library of sugar embedded macrocyclic compounds with various ring size containing 1,2,3-triazole has been developed. This concise strategy involves

• the iterative use of readily available sugar-derived alkyne/azide–alkene building blocks coupled through copper catalyzed azide–alkyne cycloaddition (CuAAC) reaction followed by pairing of the linear cyclo-adduct using greener reaction conditions. The eco-compatibility, mild reaction conditions

• synthesis of sugar-embedded glycoconjugates [52][53]. Further, the linear syntheses of macrocycles based on multistep protocols are not cost-effective and the development of efficient, sustainable, greener and economical methods is highly desired. Synthetic methods to produce a diverse collection of

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

• , the main drawbacks of this protocol are the longer reaction times (12–24 hours), the lower glycan loading and the difficulty for a fine control of the organic shell composition. The last category collects all the protocols based on chemical conjugations of sugar residues to ligands displayed on the

• metal surface of pre-formed AuNPs. Despite the longer times required for the NP synthesis and the first coating, the main advantages of this approach are the use of a lower amount of precious sugar residues and the possibility to exploit different orthogonal surface functionalizations. Reactions

• immunosorbent assay (ELISA), the selectivity and sensitivity of the binding were demonstrated to be dependent on the sugar nature and on the NP morphology. The cellular uptake experiments on HeLa, HepG2 and MDA-MB-231 cells showed in fact an higher clathrin-mediated internalization for rod-shaped AuNPs in

Use of costic acid, a natural extract from Dittrichia viscosa, for the control of Varroa destructor, a parasite of the European honey bee

• Kalliopi Sofou,
• Demosthenis Isaakidis,
• Apostolos Spyros,
• Anita Büttner,
• Athanassios Giannis and
• Haralambos E. Katerinopoulos

Beilstein J. Org. Chem. 2017, 13, 952–959, doi:10.3762/bjoc.13.96

• total volume of 1 L. In the second field test (B) a solution was prepared using 1 g of “group B” mixture diluted in sugar suryp 1:1 instead of deionized water. To allow for a comparison each bee population was divided into four groups. Two of these groups were treated with commercial acaricides. A

• fourth, the control group, was sprayed with deionized water. As commercial acaricide preparations were used a) bayvarol (active ingredient: flumethrine) and b) a 4% solution of oxalic acid in 50% sugar solution. The total volume of solutions that were sprayed directly on the bees per beehive was 200 mL

Opportunities and challenges for the sustainable production of structurally complex diterpenoids in recombinant microbial systems

• Katarina Kemper,
• Max Hirte,
• Markus Reinbold,
• Monika Fuchs and
• Thomas Brück

Beilstein J. Org. Chem. 2017, 13, 845–854, doi:10.3762/bjoc.13.85

• the diverse biosynthesis of the structurally highly diverse family of isoprenoids. Both pathways use intermediate products of the central sugar metabolism as carbon sources [25]. In most eukaryotes (all mammals, yeast, fungi, archaea and plants (more precisely in the cytosol and mitochondria)) the

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

• aldol/hemiketalization reaction of a C4 aldehyde with a C3 ketone provides the differentially protected ketoheptose building block, which can be further reacted to furnish target D-manno-heptulose. Keywords: aldol reaction; cascade reaction; D-manno-heptulose; higher-carbon sugar; ketoheptose

• ; Introduction D-manno-Heptulose is a rare naturally occurring seven-carbon sugar first isolated from avocado [1], which exhibited promising diabetogenic effects through suppression of the glucose metabolism and insulin secretion via competitive inhibition of the glucokinase pathway [2][3][4][5][6]. Accordingly

• chain elongations of aldoses employing the Henry reaction, the aldol reaction, and the Wittig reaction for the preparation of ketoheptoses [20][21][22], sugar lactones were also often utilized for the synthesis of D-manno-heptulose via reactions with C-nucleophiles or conversion into exocyclic glycals

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

• autoclave chamber with heating to 200 °C for 12 h (Scheme 3) [29]. The fluorescence emission could be tuned by changing the ratio of sugar and KH2PO4. For instance a molar ratio of 1:26 (glucose/KH2PO4) afforded blue-fluorescent CDs (QY = 0.02), whereas a 1:36 ratio yielded green-fluorescent CDs (QY = 0.01

• offers all the advantages of glucose, while already containing an N atom. A few examples in the literature have already utilised this sugar as the starting material in the synthesis of CDs with interesting results. One of the earliest examples of the hydrothermal preparation of FCDs using glucosamine

• hydrothermal synthesis of amino-functionalised green fluorescent CDs using glucosamine hydrochloride in the presence of excess sodium pyrophosphate (Na4P2O7) (Scheme 15) [19]. The team showed that heating an aqueous mixture of the sugar and Na4P2O7 for 10 h to 180 °C in a Teflon-lined autoclave resulted in

Revaluation of biomass-derived furfuryl alcohol derivatives for the synthesis of carbocyclic nucleoside phosphonate analogues

• Bemba Sidi Mohamed,
• Christian Périgaud and
• Christophe Mathé

Beilstein J. Org. Chem. 2017, 13, 251–256, doi:10.3762/bjoc.13.28

• catalytic hydrogenation of furfural; the latter is obtained from the dehydration of xylose, a 5-carbon sugar derived from vegetal biomass. Furfuryl alcohol finds widespread application in the chemical industries and for example is employed for the production of synthetic fibers, fine chemicals, etc. In fine

A postsynthetically 2’-“clickable” uridine with arabino configuration and its application for fluorescent labeling and imaging of DNA

• Heidi-Kristin Walter,
• Bettina Olshausen,
• Ute Schepers and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2017, 13, 127–137, doi:10.3762/bjoc.13.16

• structure of double-helical DNA elucidates that the positioning of the fluorophores in the major groove may be improved by inversion of the configuration at the 2’-position of the anchor nucleoside sugar. In fact, arabino nucleic acids are an important class of antisense oligonucleotides [20] since their

Diels–Alder reactions of myrcene using intensified continuous-flow reactors

• Christian H. Hornung,
• Miguel Á. Álvarez-Diéguez,
• Thomas M. Kohl and
• John Tsanaktsidis

Beilstein J. Org. Chem. 2017, 13, 120–126, doi:10.3762/bjoc.13.15

• ’ replacement of existing, fossil resources based synthesis routes with economic alternatives based on renewable sources. Besides chemical platforms based on sugar, lignin or fatty acid containing feedstocks, terpenes present another plant derived feedstock which is of great interest for a variety of industrial

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

• times as compared to benzyl. The increased reactivity of the silylated glycosyl donors is partially due to the O-silyl group being somewhat less electron withdrawing than the benzyl, but also due to the ability of bulky silyl groups to cause a change in the sugar ring conformation [21]. The influences

• effect on the basicity and the donor reactivity stems from the conformational change in the sugar ring, which causes the OR groups in the 3 and 4 and occasionally the 2-position to adopt an (pseudo)axial orientation, which is less electron withdrawing [23]. This conformational change is induced when

• having trans-vicinal OR groups (Figure 3). Normally the bisequatorial orientation is preferable due to 1,3-diaxial interactions of axial substituents. This steric interaction can however be overridden when the R groups are sufficient bulky and hence the sugar ring changes the conformation. The

Versatile synthesis of end-reactive polyrotaxanes applicable to fabrication of supramolecular biomaterials

• Atsushi Tamura,
• Asato Tonegawa,
• Yoshinori Arisaka and
• Nobuhiko Yui

Beilstein J. Org. Chem. 2016, 12, 2883–2892, doi:10.3762/bjoc.12.287

• obtained from NOF Corporation (Tokyo, Japan). α-Cyclodextrin (α-CD) was obtained from Ensuiko Sugar Refining (Tokyo, Japan). 4-(Azidomethyl)benzoic acid was synthesized according to the previous report [27]. 4-Azidobenzoic acid, 4-methylbenzoic acid, p-(tert-butyl)phenylacetylene, and 2-(2-hydroxyethoxy

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

• organic synthesis in view of their compatibility with a wide range of conditions. Their regioselective installation on polyols generally requires lengthy reactions and the use of high boiling solvents. In the first part of this paper we demonstrate that regioselective silylation of sugar polyols can be

• very recently described also with the above mentioned method based on silyl methallylsulfinates [23]. On the other hand, the method herein proposed was found compatible with a reducing sugar such as D-mannose, which was converted in a good yield into the corresponding 6-O-silylated product 13, isolated

• compounds. Regioselective silylation of 1 under solvent free conditionsa. Regioselective silylation of saccharide primary alcohols under solvent-free conditionsa. Solvent-free regioselective silylations committing secondary alcoholsa. One-pot, regioselective protection of sugar polyols with silyl and alkyl

A versatile route to polythiophenes with functional pendant groups using alkyne chemistry

• Xiao Huang,
• Li Yang,
• Rikard Emanuelsson,
• Jonas Bergquist,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 2682–2688, doi:10.3762/bjoc.12.265

• economically available D-mannitol diketal, 1,2:5,6-bis-O-(1-methylethylidene)-D-mannitol which can be obtained via the hydrogenation of common table sugar [32]. Oxidation of this diketal by NaIO4 led to glyceraldehyde [33], which was transformed into the dibromoolefin 5 by Corey–Fuchs reaction. Dibromoolefin 5

Formose reaction controlled by boronic acid compounds

• Toru Imai,
• Tomohiro Michitaka and
• Akihito Hashidzume

Beilstein J. Org. Chem. 2016, 12, 2668–2672, doi:10.3762/bjoc.12.263

• SPB, whereas sugar alcohols of a larger carbon number were formed preferably in the presence of pVPB/NaSS. Keywords: boronic acid compounds; formose reaction; sodium phenylboronate; sodium 4-vinylphenylboronate/sodium 4-styrenesulfonate copolymer; sugar alcohols; sugars; Findings When an aqueous

• solution of formaldehyde is warmed in the presence of a basic catalyst, a mixture of sugars and sugar alcohols, i.e., ‘formose’, is obtained. This reaction is called ‘formose reaction’ and was first reported by Butlerow, a Russian chemist, in 1861 [1]. Studies on formose reactions have revealed that the

• formose reaction consists of several elemental reaction steps, e.g., acyloin condensation, aldol reaction, retro-aldol reaction, aldose–ketose isomerization, and Cannizzaro reaction, and the product, formose, is a complicated mixture of more than thirty species of sugars and sugar alcohols including non

Formose reaction accelerated in aerosol-OT reverse micelles

• Makoto Masaoka,
• Tomohiro Michitaka and
• Akihito Hashidzume

Beilstein J. Org. Chem. 2016, 12, 2663–2667, doi:10.3762/bjoc.12.262

• mixture of sugars and sugar alcohols, called ‘formose’, from formaldehyde by heating under basic conditions. It has been considered that the formose reaction is a possible pathway for sugar formation under prebiotic conditions [1][2][3][4]. The formose reaction was first reported by Butlerow in 1861 [5

• ]. Studies on the formose reaction by a number of researchers have revealed that the formose reaction consists of three periods, i.e., the induction period, the sugar formation period, and the sugar degradation period [6]. In the induction period two formaldehyde molecules form glycolaldehyde, which is the

• transformation in the sugar formation period. When formaldehyde is consumed quantitatively, the reaction mixture turns yellow. In the sugar degradation period, the sugars formed are decomposed dominantly through cross-Cannizzaro reaction and retro-aldol reaction to form a more complicated reaction mixture. The

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

• -mannose, D- and L-fucose, and methyl α-D-fucopyranoside) were not complexed (binding constants ≈ “0” M−1). These binding constants can be directly correlated to the hydrophobicity of the sugar. Nevertheless, the H-bonds between the hydroxy groups of bound sugar and the OH groups of β-CD are also extremely

• ] and the binding constants obtained by these three groups are reported in Table 4. These values are relatively close to each other and the sugar/β-CD binding constants increase in the order of D-galactose ≈ D-glucose < D-mannose < D-arabinose < D-xylose < D-ribose. This magnitude is consistent with the

• order of magnitude of the sugar hydrophobicity scale determined by Janado and Yano in 1985 (Scheme 4) [100]. This hydrophobicity scale is corroborated by Wei and Pohorille for the hexose series [101]. Therefore, even if all the literature values for the binding constants obtained by the different

Synthesis of polyhydroxylated decalins via two consecutive one-pot reactions: 1,4-addition/aldol reaction followed by RCM/syn-dihydroxylation

• Michał Malik and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2016, 12, 2602–2608, doi:10.3762/bjoc.12.255

• 1,4-addition of vinylmagnesium bromide to sugar-derived cyclohexenone, followed by an aldol reaction with a derivative of but-3-enal. The obtained diene is then subjected to an assisted tandem catalytic sequence: ring-closing metathesis with the subsequent reuse of the Ru-catalyst in the syn

• -decalins and trans-hydrindanes (Scheme 1) [22][23][24][25]. It relies on the use of sugar-derived allyltin (such as 5) followed by ZnCl2-induced fragmentation into dienoaldehyde 6, subsequent Horner–Wadsworth–Emmons olefination, and intramolecular Diels–Alder reaction. In this paper, we explore the

• possibility of using a copper-catalyzed one-pot 1,4-addition of vinylmagnesium bromide to sugar-derived cyclic α,β-unsaturated ketones (such as 9), followed by an aldol reaction with an optically pure derivative of but-2-enal 10 to obtain a mixture of diastereomeric dienes, such as 11 (Scheme 2). As a result

Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

• Vladimir A. Stepchenko,
• Anatoly I. Miroshnikov,
• Frank Seela and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2016, 12, 2588–2601, doi:10.3762/bjoc.12.254

• of 2,4-di-O-TMS derivatives accompanied by the sp3 → sp2 transformation of the nitrogen atoms. The sp2 hybridized nitrogen atoms attack the electrophilic C-1 carbon atom of the appropriately protected sugar derivatives leading to the glycosylic bond formation (reviewed in [25]). A similar mechanism

• thymidine, uridine and its deoxy- (2'- and 5'-monodeoxy and 2',3'-dideoxy) and arabino derivatives, and (ii) the conversion of 5-fluoro (Br, I, CF3 and –CH=CHBr)-uracil into respective 2'-deoxyribosides (2'-deoxyuridine as a donor of the sugar moiety) was studied in detail by Ubiali et al. [70]. Tested in