Biosynthesis of rare hexoses using microorganisms and related enzymes

• Zijie Li,
• Yahui Gao,
• Hideki Nakanishi,
• Xiaodong Gao and
• Li Cai

Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281

• pharmaceutical and nutrition industry [4]. In recent years, the interest in rare carbohydrates and the nucleosides (e.g. L-nucleoside analogues) derived from them has substantially increased in medicine because these molecules are potential candidates of anticancer and antiviral drugs [4][5][6]. Unfortunately

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• the strongest free-radical oxidants known [E(NO3•/NO3−) = 2.3–2.5 V vs NHE] [9], and recent product studies by us revealed that NO3• readily damages aromatic amino acids and pyrimidine nucleosides through an oxidative pathway [10][11][12][13]. Thus, the ease by which model compounds of biologically

• ratio towards the nitrate 4 at expense of the higher oxidized products 5 and 6 (data not shown). The observed side-chain oxidation in 3 by NO3• is similar to the outcome of the reaction of thymidine nucleosides with NO3•, where oxidative transformation of the methyl substituent in the heterocyclic base

• for the reaction of NO3• with alkylaromatic compounds [22][23]. In the absence of any reactants the resulting radical cation 3•+ undergoes deprotonation to give benzyl radical 7, in analogy to the mechanism of the NO3•-induced oxidation of aromatic amino acids and nucleosides [10][11][12][13]. This

Efficient continuous-flow synthesis of novel 1,2,3-triazole-substituted β-aminocyclohexanecarboxylic acid derivatives with gram-scale production

• Sándor B. Ötvös,
• Ádám Georgiádes,
• István M. Mándity,
• Lóránd Kiss and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2013, 9, 1508–1516, doi:10.3762/bjoc.9.172

• in Figure 1) [8][9]. The 1,2,3-triazole moiety is a constituent part of many modified nucleosides or carbanucleosides with antiviral, anti-HIV or cytostatic activities [10][11][12]. However, the scope of triazole chemistry is not confined to drug discovery. There are an increasing number of

Conformational analysis and intramolecular interactions in monosubstituted phenylboranes and phenylboronic acids

• Josué M. Silla,
• Rodrigo A. Cormanich,
• Roberto Rittner and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2013, 9, 1127–1134, doi:10.3762/bjoc.9.125

• transpeptidases [1][2]. Other important studies incorporate the boronic acid moiety into amino acids and nucleosides as antitumor and antiviral agents [3][4]. Indeed, the great importance of aromatic boronic acids to biological and pharmaceutical purposes has been reported, as well as the interest to introduce a

Methylidynetrisphosphonates: Promising C₁ building block for the design of phosphate mimetics

• Vadim D. Romanenko and
• Valery P. Kukhar

Beilstein J. Org. Chem. 2013, 9, 991–1001, doi:10.3762/bjoc.9.114

• and coordination properties thus providing excellent possibilities for the design of effective phosphate mimetics. Especially successful so far seem to be approaches for the synthesis of trisphosphonate-modified nucleotides and nucleosides, which represent a promising class of potential drugs [8

A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors

• El Sayed H. El Ashry,
• El Sayed H. El Tamany,
• Mohy El Din Abdel Fattah,
• Mohamed R. E. Aly,
• Ahmed T. A. Boraei and
• Axel Duerkop

Beilstein J. Org. Chem. 2013, 9, 135–146, doi:10.3762/bjoc.9.16

• crystallography. Finally, action of ammonia on benzylated 3-N-(galactosyl)oxadiazolinethione unexpectedly yielded 3-N-(galactosyl)triazolinethione. This represents a new path to the conversion of glycosyloxadiazolinethiones to new glycosyltriazolinethione nucleosides, which was until now unknown. Keywords

• : glycosyloxadiazolinethiones; glycosylsulfanyloxadiazoles; glycosylthiosemicarbazides; thermal rearrangement; X-ray crystallography; Introduction Modified nucleosides are versatile motifs for studying the relationship between the structure and functions of nucleic acids and problems of metabolism, besides their main

• with inhibition constants in the low micromolar range [2]. Coupling of aglycones with relevant glycosyl donors is the common approach involved in the synthesis of most nucleosides. Another strategy for the synthesis of nucleoside analogues is the use of glycosylamines and related N-bonded glycosides [3

An improved synthesis of a fluorophosphonate–polyethylene glycol–biotin probe and its use against competitive substrates

• Hao Xu,
• Hairat Sabit,
• Gordon L. Amidon and
• H. D. Hollis Showalter

Beilstein J. Org. Chem. 2013, 9, 89–96, doi:10.3762/bjoc.9.12

• stage was now set for a two-step modification of the phosphonate moiety. Reaction of 8 with lithium azide in hot DMF, under conditions developed for the monodealkylation of phosphonic acid dialkyl esters of nucleosides [19], provided the novel monoethyl ester 9 in 87% yield following purification by a

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

Recyclable fluorous cinchona alkaloid ester as a chiral promoter for asymmetric fluorination of β-ketoesters

• Wen-Bin Yi,
• Xin Huang,
• Zijuan Zhang,
• Dian-Rong Zhu,
• Chun Cai and
• Wei Zhang

Beilstein J. Org. Chem. 2012, 8, 1233–1240, doi:10.3762/bjoc.8.138

• . Introducing one or a few fluorine atoms to biologically interesting molecules can significantly change the physical, chemical and biological properties [1][2]. The significant amount of publications on fluorinated small molecules, amino acids, carbohydrates, steroids and nucleosides indicates that

The effect of the formyl group position upon asymmetric isomeric diarylethenes bearing a naphthalene moiety

• Renjie Wang,
• Shouzhi Pu,
• Gang Liu and
• Shiqiang Cui

Beilstein J. Org. Chem. 2012, 8, 1018–1026, doi:10.3762/bjoc.8.114

• nucleosides and molecular recognition properties of nucleic acids with the light sensitivity of diarylethenes [34]. Recently, Wu et al. designed and synthesized a novel diarylethene-containing dithiazolethene, which exhibited a gated photochromic reactivity controlled by complexation/dissociation with BF3 [35

Diarylethene-modified nucleotides for switching optical properties in DNA

• Sebastian Barrois and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2012, 8, 905–914, doi:10.3762/bjoc.8.103

• photochromic nucleosides. All nucleosides were characterized with respect to their absorption and photochromic properties. Based on these results, the most promising photochromic DNA base modification was incorporated into representative oligonucleotides by using automated phosphoramidite chemistry. The

• photoswitchable components in nucleic acids and are suitable for the control of a variety of different biological functions. The photoinduced cis–trans isomerization of azobenzene nucleosides can reversibly switch between the formation and dissociation of DNA duplexes [14][15][16][17], photoregulate DNA

• [29][30], into oligonucleotides (Scheme 1). Although the spiropyran DNA building blocks 1 and 2 exhibit promising photochromic properties as nucleosides, it is not worth pursuing this synthetic direction further for the following reasons [30]: (i) It is reported that spiropyrans decompose in aqueous

Enantioselective supramolecular devices in the gas phase. Resorcin[4]arene as a model system

• Caterina Fraschetti,
• Matthias C. Letzel,
• Antonello Filippi,
• Maurizio Speranza and
• Jochen Mattay

Beilstein J. Org. Chem. 2012, 8, 539–550, doi:10.3762/bjoc.8.62

• ligand-exchange enantioselectivity of [V·H·amph]+ is determined by the effects of the chiral resorcin[4]arene scaffold upon the transition-state structures involved in the reaction, similarly to the complex of V with catharanthine. Rigid resorcin[4]arenes as chiral selectors of nucleosides. Nucleosides

• nucleosides can be an inspiration for both the design of new drug carriers, characterized by high solubility and selectivity, and a better understanding of the selective uptake of nucleosides by their respective membrane receptors [55]. The selected pyrimidine nucleosides are reported in Figure 8, i.e., 2

• resorcin[4]arene coordinating to B (k2). The 1011k1/k−1 and k−1/k2 ratios are reported in Table 3. The basicity of the nucleosides decreases in the order: dC < CT = Cy < GC, and in the same order the 1011k1/k−1 ratio tends to increase, most probably because the partial positive charge on the host pendants

Selectivity in C-alkylation of dianions of protected 6-methyluridine

• Ngoc Hoa Nguyen,
• Christophe Len,
• Anne-Sophie Castanet and
• Jacques Mortier

Beilstein J. Org. Chem. 2011, 7, 1228–1233, doi:10.3762/bjoc.7.143

• construction of C-substituted nucleosides are based on ring lithiation of nucleoside derivatives followed by their reaction with appropriate electrophiles. Thus, sequential lithiation of 2',3'-O-isopropylideneuridine (6) with LDA in THF (Figure 1) and electrophilic quenching with n-bromobutane was reported to

• performed with fully TBDMS-protected ribofuranose nucleosides to allow better regiochemical control and to prevent nucleophilic attack of the base on the sugar moiety [48]. Conclusion In summary, a straightforward approach to 6-ω-alkenyluridines 3 from readily available protected uridine 1 is proposed

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• , cytotoxic and antibacterial, is also reported. Keywords: 5-alkoxymethyluracil; biological activity; nucleosides; Review Introduction Modifications of nucleic acid components play a significant role in the field of nucleic acids research. In particular, nucleoside analogues find broad therapeutic

• . Synthesis Synthesis of alkoxy-haloalkyl derivatives The most numerous and also the most investigated group of the above mentioned derivatives is a group of alkoxy-haloalkyl compounds derived either from uracil or nucleosides (Figure 2). With regard to the high variability of sugar moiety, the description of

• all the compounds is divided into sections according to the nature of the furanose present. 2'-Deoxyuridine analogues: The earliest article describing 2'-deoxyuridine analogues was focused on uracil analogues modified at position 5 by a fluorine containing moiety [6]. Bases or nucleosides substituted

Systematic investigations on the reduction of 4-aryl-4-oxoesters to 1-aryl-1,4-butanediols with methanolic sodium borohydride

• Subrata Kumar Chaudhuri,
• Manabendra Saha,
• Amit Saha and
• Sanjay Bhar

Beilstein J. Org. Chem. 2010, 6, 748–755, doi:10.3762/bjoc.6.94

• LiAlH4 which also often gives rise to several non-identifiable by-products. Structurally varied 1-aryl-1,4-butanediols are of great synthetic value with immense applications in cationic polymerizations [34], as intermediates for the syntheses of important acyclic antiviral nucleosides [35] and cyclic

Synthesis of some novel hydrazono acyclic nucleoside analogues

• Mohammad N. Soltani Rad,
• Ali Khalafi-Nezhad and
• Somayeh Behrouz

Beilstein J. Org. Chem. 2010, 6, No. 49, doi:10.3762/bjoc.6.49

• Abstract The syntheses of novel hydrazono acyclic nucleosides similar to miconazole scaffolds are described. In this series of acyclic nucleosides, pyrimidine as well as purine and other azole derivatives replaced the imidazole function in miconazole and the ether group was replaced with a hydrazone moiety

• established in medicinal chemistry [13][14][15][16]. Acyclic nucleosides constitute a special class of nucleoside analogues which have attracted great interest due to their broad-spectrum chemotherapeutic activities against cancer and infections caused by viruses, microbes and other pathogenic microorganisms

• . Moreover, antitumor and antiviral activities of various hydrazone derivatives of nucleosides have also been reported [16][17][18]. Inspired by the miconazole scaffold and also as an extension of our ongoing research in the design and synthesis of novel acyclic nucleosides [19][20][21][22][23][24][25

Symmetrical and unsymmetrical α,ω-nucleobase amide-conjugated systems

• Sławomir Boncel,
• Maciej Mączka,
• Krzysztof K. K. Koziol,
• Radosław Motyka and
• Krzysztof Z. Walczak

Beilstein J. Org. Chem. 2010, 6, No. 34, doi:10.3762/bjoc.6.34

• nanofibres. Keywords: amides; antiprotozoal agents; coupling; nucleosides; self-assembly; Introduction There are numerous reports on the synthesis and application of symmetrical and unsymmetrical α,ω-nucleobase amide-conjugated systems (Figure 1) [1][2][3][4][5][6]. These molecules are constructed usually

• ,ω-nucleobase bolaamphiphiles (VII), capable of forming extraordinary nanotopologies [6]. In order to synthesise a new group of modified, mainly pyrimidinic nucleosides, we employed a simple and effective synthetic pathway based on the catalytic aminolysis of carboxylic acids. Our synthetic approach

• synthesis of N-Boc monoprotected amine reactant 17 (See Supporting Information File 1). The compounds in this second group were obtained in yields of 31–95%. The synthesis of nucleosides containing aliphatic linkages (19–22) presented no difficulties on work-up. Two different acidic and three different

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

Synthetic incorporation of Nile Blue into DNA using 2′-deoxyriboside substitutes: Representative comparison of (R)- and (S)-aminopropanediol as an acyclic linker

• Daniel Lachmann,
• Sina Berndl,
• Otto S. Wolfbeis and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2010, 6, No. 13, doi:10.3762/bjoc.6.13

• the chromophore to intercalate. The major difference between the 3-amino-1,2-propanediol linker and the 2′-deoxyribofuranoside is the number of carbon atoms between the phosphodiester bridges in the corresponding modified oligonucleotides which has been reduced from 3 (in normal nucleosides) to 2

Understanding the mechanism of Pd-catalyzed allylic substitution of the cyclic difluorinated carbonates

• Jun Xu,
• Xiao-Long Qiu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2008, 4, No. 18, doi:10.3762/bjoc.4.18

• , Shanghai 201620, China 10.3762/bjoc.4.18 Abstract We present a mechanistic investigation of Pd-catalyzed allylic substitution of cyclic gem-difluorinated carbonates 1 and 4, previously employed in the synthesis of 3',3'-difluoro-2'-hydroxymethyl-4',5'-unsaturated carbocyclic nucleosides in 17 steps. The

• substitution features a reversal of regioselectivity caused by fluorine. Background Carbocyclic nucleosides (CNAs), in which the furanose oxygen atoms of the 4'-oxonucleosides are substituted by CH2, have received considerable attention because they exhibit greater metabolic stability toward nucleoside

• phosphorylases and higher lipophilicity, two properties that are potentially beneficial in terms of increased in vivo half life, oral efficiency and cell wall penetration [1][2]. Based on CNA skeletons, 1,2-disubstituted carbocyclic nucleosides (OTCs) recently attracted more and more attention [3][4][5][6][7][8

N-1 regioselective Michael- type addition of 5-substituted uracils to (2-hydroxyethyl) acrylate

• Sławomir Boncel,
• Dominika Osyda and
• Krzysztof Z. Walczak

Beilstein J. Org. Chem. 2007, 3, No. 40, doi:10.1186/1860-5397-3-40

• participation of hydroxyl group, into ester-conjugated acyclic nucleosides. Background Nowadays, intensive research on the preparation of novel synthetic nucleosides plays an important role in the research scopes of academic bioorganic centres. Special attention has been reserved in the current synthesis

• literature for acyclic nucleosides.[1] Acyclic units containing hydroxyl groups are capable of phosphorylation and building into a growing nucleic acid, thus perturbing its replication. Several acyclic nucleosides, like HEPT (1-[2-hydroxyethoxymethyl]-6-(phenylthio)thymine),[2] or MKC-442 (1-ethoxymethyl-5

• ] Following our aims, to synthesise ester-conjugated nucleosides, we would like to present an expedient method of uracil ring alkylation, with the potential for further functionalization towards acyclic nucleosides. 2-Hydroxyethyl acrylate (HEA), being a widely exploited monomer in the production of

Synthesis of coumarin or ferrocene labeled nucleosides via Staudinger ligation

• Ivana Kosiova,
• Andrea Janicova and
• Pavol Kois

Beilstein J. Org. Chem. 2006, 2, No. 23, doi:10.1186/1860-5397-2-23

• nucleic acids. Results A new approach for the preparation of labeled nucleosides via intermolecular Staudinger ligation is described. Reaction of azidonucleosides with triphenylphosphine lead to iminophosphorane intermediates, which react subsequently with derivatives of coumarin or ferrocene to form

• coumarin or ferrocene labeled nucleosides. Fluorescent properties of coumarin labeled nucleosides are determined. Conclusion New coumarin and ferrocene labeled nucleosides were prepared via intermolecular Staudinger ligation. This reaction joins the fluorescent coumarin and biospecific nucleoside to the

• nucleosides are important tools for the study of key processes of cell metabolism, as well as being successful therapeutic agents. [1][2][3] For structural and functional studies of nucleosides, and their oligomers in nucleic acids or protein complexes, efficient detection methods are necessary. Today

The first salen- type ligands derived from 3',5'-diamino- 3',5'-dideoxythymidine and -dideoxyxylothymidine and their corresponding copper(II) complexes

• Daniel Koth,
• Michael Gottschaldt,
• Helmar Görls and
• Karolin Pohle

Beilstein J. Org. Chem. 2006, 2, No. 17, doi:10.1186/1860-5397-2-17

• with xylo- as well as ribo-configuration an effective synthesis pathway has been developed. Their corresponding salicylidene imines form stable coordination compounds with copper(II) ions. They represent the first salen type complexes of nucleosides with this substitution pattern. Background Complexes

• of diimino functionalized ligands are often used as catalysts for a wide variety of reactions. Enantioselective synthesis has gained in importance in the last few years, and the development of chiral ligands has become an important field in organic chemistry. Nucleosides provide a stable scaffold

• containing three (DNA nucleosides) and four (RNA nucleosides) chiral centers respectively. Though the coordination of metal ions to nucleosides is well known, mostly the nucleobase interacts with the metal centre, and the chiral part of the nucleoside is not involved in the coordination. [1][2] Although a