- A facile synthesis of 9-(1,3-dihydroxy-2-propoxymethyl)guanine (ganciclovir) from guanosine
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The potent and selective antiviral drug ganciclovir (6) has been synthesized in two steps via transpurination of fully acetylated guanosine (1) in the presence of 1,3-diacetoxy-2-(acetoxymethoxy)propane (2), followed by deacetylation in aqueous ammonia. The transpurination reaction also provides valuable side products, tetra-O-acetyl-β-D-ribofuranose (5) and the 7-regioisomer of triacetylganciclovir (4); the latter product can be converted to the desired 9-isomer in a thermal 7 ? 9 isomerization.
- Boryski, Jerzy,Golankiewicz, Bozenna
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Read Online
- Syntheses of 1-thio-D-xylose and D-ribose esters of diorganoarsinous acids and their anticancer activity
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Several thio-D-xylose and D-ribose esters of dialkylarsinous acids have been synthesized. The crystal structure of 1-S-dimethylarsino-β-D- xylopyranose, 7a, has been obtained. Growth inhibition studies of about 60 strains of human cancer cells have been obtained in vitro for compounds 6a, 7a, 13, and 14. The results reveal that these compounds display a strong inhibition to subpanels of leukemia cells in vitro and high selectivity in inhibiting the growth of cancer cells.
- Gao, Mingzhang,Chen, Yiwen,Tan, Songde,Reibenspies, Joseph H.,Zingaro, Ralph A.
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Read Online
- The First Analog of Pyrimidine Nucleosides with Two Nucleobases and Two d-Ribofuranose Residues
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Abstract: The reaction of 1,5-bis[1-(prop-2-yn-1-yl)uracil-3-yl]pentane with 2',3',5'-tri-O-acetyl-β-d-ribofuranosylazide followed by removing of acetyl protective groups with a solution of sodium methylate in methanol afforded 1,5-bis{[1-methyl(β-d-ribofuranosyl)-1H-1,2,3-triazole-4-yl]uracil-3-yl}pentane which is the first analog of pyrimidine nucleosides with two nucleobases and two d-ribofuranose residues.
- Andreeva,Saifina,Belenok,Semenov,Kataev
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p. 292 - 296
(2021/03/26)
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- Synthesis and antiviral evaluation of nucleoside analogues bearing one pyrimidine moiety and two d-ribofuranosyl residues
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A series of 1,2,3-triazolyl nucleoside analogues in which 1,2,3-triazol-4-yl-β-D-ribofuranosyl fragments are attached via polymethylene linkers to both nitrogen atoms of the heterocycle moiety (uracil, 6-methyluracil, thymine, quinazoline-2,4-dione, alloxazine) or to the C-5 and N-3 atoms of the 6-methyluracil moiety was synthesized. All compounds synthesized were evaluated for antiviral activity against influenza virus A/PR/8/34/(H1N1) and coxsackievirus B3. Antiviral assays revealed three compounds, 2i, 5i, 11c, which showed moderate activity against influenza virus A H1N1 with IC50 values of 57.5 μM, 24.3 μM, and 29.2 μM, respectively. In the first two nucleoside analogues, 1,2,3-triazol-4-yl-β-D-ribofuranosyl fragments are attached via butylene linkers to N-1 and N-3 atoms of the heterocycle moiety (6-methyluracil and alloxazine, respectively). In nucleoside analogue 11c, two 1,2,3-triazol-4-yl-2′,3′,5′-tri-O-acetyl-β-D-ribofuranose fragments are attached via propylene linkers to the C-5 and N-3 atoms of the 6-methyluracil moiety. Almost all synthesized 1,2,3-triazolyl nucleoside analogues showed no antiviral activity against the coxsackie B3 virus. Two exceptions are 1,2,3-triazolyl nucleoside analogs 2f and 5f, in which 1,2,3-triazol-4-yl-2′,3′,5′-tri-O-acetyl-β-D-ribofuranose fragments are attached to the C-5 and N-3 atoms of the heterocycle moiety (6-methyluracil and alloxazine respectively). These compounds exhibited high antiviral potency against the coxsackie B3 virus with IC50 values of 12.4 and 11.3 μM, respectively, although both were inactive against influenza virus A H1N1. According to theoretical calculations, the antiviral activity of the 1,2,3-triazolyl nucleoside analogues 2i, 5i, and 11c against the H1N1 (A/PR/8/34) influenza virus can be explained by their influence on the functioning of the polymerase acidic protein (PA) of RNA-dependent RNA polymerase (RdRp). As to the antiviral activity of nucleoside analogs 2f and 5f against coxsackievirus B3, it can be explained by their interaction with the coat proteins VP1 and VP2.
- Andreeva, Olga V.,Belenok, Mayya G.,Garifullin, Bulat F.,Kataev, Vladimir E.,Lyubina, Anna P.,Man’kova, Maria A.,Saifina, Liliya F.,Semenov, Vyacheslav E.,Shulaeva, Marina M.,Slita, Alexander V.,Volobueva, Alexandrina S.,Voloshina, Alexandra D.,Yesaulkova, Iana L.,Zarubaev, Vladimir V.
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- Synthesis of 1,2,3-triazolyl nucleoside analogues and their antiviral activity
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Abstract: Based on the fact that a search for influenza antivirals among nucleoside analogues has drawn very little attention of chemists, the present study reports the synthesis of a series of 1,2,3-triazolyl nucleoside analogues in which a pyrimidine fragment is attached to the ribofuranosyl-1,2,3-triazol-4-yl moiety by a polymethylene linker of variable length. Target compounds were prepared by the Cu alkyne-azide cycloaddition (CuAAC) reaction. Derivatives of uracil, 6-methyluracil, 3,6-dimethyluracil, thymine and quinazolin-2,4-dione with ω-alkyne substituent at the N1 (or N5) atom and azido 2,3,5-tri-O-acetyl-D-β-ribofuranoside were used as components of the CuAAC reaction. All compounds synthesized were evaluated for antiviral activity against influenza virus A/PR/8/34/(H1N1) and coxsackievirus B3. The best values of IC50 (inhibiting concentration) and SI (selectivity index) were demonstrated by the lead compound 4i in which the 1,2,3-triazolylribofuranosyl fragment is attached to the N1 atom of the quinazoline-2,4-dione moiety via a butylene linker (IC50 = 30?μM, SI = 24) and compound 8n in which the 1,2,3-triazolylribofuranosyl fragment is attached directly to the N5 atom of the 6-methyluracil moiety (IC50 = 15?μM, SI = 5). According to theoretical calculations, the antiviral activity of the 1,2,3-triazolyl nucleoside analogues 4i and 8n against H1N1 (A/PR/8/34) influenza virus can be explained by their influence on the functioning of the polymerase acidic protein (PA) of RNA-dependent RNA polymerase (RdRP). Graphic abstract: [Figure not available: see fulltext.]
- Andreeva, Olga V.,Garifullin, Bulat F.,Zarubaev, Vladimir V.,Slita, Alexander V.,Yesaulkova, Iana L.,Saifina, Liliya F.,Shulaeva, Marina M.,Belenok, Maya G.,Semenov, Vyacheslav E.,Kataev, Vladimir E.
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p. 473 - 490
(2020/09/22)
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- A Synthesis Strategy for the Production of a Macrolactone of Gulmirecin A via a Ni(0)-Mediated Reductive Cyclization Reaction
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A synthesis strategy for the production of a key synthetic intermediate of gulmirecin A was described. The key reaction in the preparation of the 12-membered macrolactone is the Ni(0)-mediated reductive cyclization reaction of ynal using an N-heterocyclic carbene ligand and silane reductant. In addition, the α-selective glycosylation reaction of the macrolactone was performed to demonstrate the synthesis of gulmirecin and disciformycin precursors.
- Ichikawa, Satoshi,Katsuyama, Akira,Kitahata, Shun
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supporting information
(2020/03/30)
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- Synthesis of benzimidazole nucleosides and their anticancer activity
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An efficient route for the synthesis of benzimidazole nucleosides 1–8 from readily available D-glucose via 3,5-dihydroxy-1,2-O-isopropylidene-α-D-ribofuranose and 3-azido-3-deoxy-1,2-O-isopropylidene-α-D-xylofuranose intermediates has been adopted. Ribofuranosyl nucleosides 1–4 with different benzimidazole bases, and 3?-deoxy-3?-azido-ribofuranosyl nucleosides 5–8, as another series, were obtained. All these newly synthesized analogs were evaluated for anticancer activity using MDA-MB-231 cell line. Among the differently substituted derivatives, 3?-azide substituted nucleosides (5–8) are more potent compared to ribofuranosyl analogs 1–4. The C-3?-azido analog 8 having anthryl group at 2-position of nucleobase show almost similar potency as that of standard etoposide.
- Khan, Ayesha,Lawande, Pravin P.,Shinde, Vaishali S.,Sontakke, Vyankat A.
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supporting information
(2020/10/12)
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- Glycosides and Glycoconjugates of the Diterpenoid Isosteviol with a 1,2,3-Triazolyl Moiety: Synthesis and Cytotoxicity Evaluation
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Several glycoconjugates of the diterpenoid isosteviol (16-oxo-ent-beyeran-19-oic acid) with a 1,2,3-triazolyl moiety were synthesized, and their cytotoxicity was evaluated against some human cancer and normal cell lines. Most of the synthesized compounds demonstrated weak inhibitory activities against the M-HeLa and MCF-7 human cancer cell lines. Three lead compounds, 54, 56 and 57, exhibited high selective cytotoxic activity against M-HeLa cells (IC50 = 1.7-1.9 μM) that corresponded to the activity of the anticancer drug doxorubicin (IC50 = 3.0 μM). Moreover, the lead compounds were not cytotoxic with respect to a Chang liver human normal cell line (IC50 > 100 μM), whereas doxorubicin was cytotoxic to this cell line (IC50 = 3.0 μM). It was found that cytotoxic activity of the lead compounds is due to induction of apoptosis proceeding along the mitochondrial pathway. The present findings suggest that 1,2,3-triazolyl-ring-containing glycoconjugates of isosteviol are a promising scaffold for the design of novel anticancer agents.
- Andreeva, Olga V.,Garifullin, Bulat F.,Sharipova, Radmila R.,Strobykina, Irina Yu.,Sapunova, Anastasiya S.,Voloshina, Alexandra D.,Belenok, Mayya G.,Dobrynin, Alexey B.,Khabibulina, Leysan R.,Kataev, Vladimir E.
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p. 2367 - 2380
(2020/08/28)
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- Synthesis of novel 1,2,3-triazolyl nucleoside analogues bearing uracil, 6-methyluracil, 3,6-dimethyluracil, thymine, and quinazoline-2,4-dione moieties
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A series of novel 1,2,3-triazolyl nucleoside analogues was synthesized via the CuAAC reaction of N1-alkynyl uracil, 6-methyluracil, 3,6-dimethyl uracil, thymine and quinazolin-2,4-dione with protected azido β-D-ribofuranose. The obtained compounds differ in both the nature of the pyrimidine-2,4-dione fragment and the length of the polymethylene linker connecting it with the β-D-ribofuranosyl-1,2,3-triazol-4-yl moiety. The 1,2,3-triazolyl nucleoside analogues were evaluated for their cytotoxicity in vitro.
- Andreeva, Olga V.,Belenok, Maya G.,Saifina, Liliya F.,Shulaeva, Marina M.,Dobrynin, Alexey B.,Sharipova, Radmila R.,Voloshina, Alexandra D.,Saifina, Alina F.,Gubaidullin, Aidar T.,Khairutdinov, Bulat I.,Zuev, Yuriy F.,Semenov, Vyacheslav E.,Kataev, Vladimir E.
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- Preparation of L-ribavirin (by machine translation)
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The invention provides a method for the preparation of ribavirin, to inosine as raw materials, after acetylation, condensation, aminolysis step to obtain the target product, the alkali in the acylation reaction of aluminum trichloride as a catalyst is conducted under the condition of, said condensation is in the NaI is conducted under the conditions of the catalyst, the aminolysis in methanol of existence of the sodium is conducted under the condition of. The method improves the acetylation efficiency, improves the yield of target product purity, shortens the reaction time, more easy to operate, is very suitable for industrial application. (by machine translation)
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Paragraph 0022; 0026; 0038
(2018/04/03)
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- Stereoselective acetylation of hemicellulosic C5-sugars
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The stereoselective peracetylation of α-D-xylose (1) and α-L-arabinose (4) using a combination of triethylamine and acetic anhydride in the presence or absence of a catalytic amount of dimethylaminopyridine (DMAP) is described. The peracetylated D-xylose and L-arabinose alpha pyranose anomers 2α and 5α are obtained in 97% and 56% yields respectively. The peracetylated D-xylose beta pyranose anomer 2β is obtained in 71% yield through simple modification of the reaction conditions. Details regarding synthesis and isolation optimization studies under different conditions are presented below. The stereoselective peracetylation reactions disclosed here have been used to separate mixtures of D-xylose and L-arabinose as their peracetylated derivatives 2β and 5α in 47% and 42% yields and can provide pure pentoses after deacetylation.
- Herde, Zachary D.,John, Prathap D.,Alvarez-Fonseca, Dania,Satyavolu, Jagannadh,Burns, Christopher T.
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- Utilization method of waste alpha-1,2,3,5-tetra-O-acetyl-D-ribose in ribose crystalline residual liquid
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The invention relates to a method for utilizing waste in ribose crystalline residual liquid. The method comprises the steps that crystalline residual liquid obtained after nucleoside pyrolysis serves as a raw material, an organic layer is extracted, an organic solvent is vaporized and eliminated, mixing is conducted with benzotriazole, under the action of a catalyst, on the condition that the temperature ranges from 100 DEG C to 160 DEG C, a condensation reaction is conducted for 0.33-5.0 h, after the reaction is completed, ethyl acetate is added for dissolving, washing is conducted with water, the solvent is dried out, recrystallization is conducted with diethyl ether, an intermediate product 1-(2,3,5-tri-O-acetyl-beta-D-furanribosyl)benzotriazole is obtained, under the faction of an aminomethanol solution or a sodium methylate methanol solution, acetyl is removed at room temperature, and 1-(2,3,5-tri-hydroxyl-beta-D-furanribosyl)benzotriazole is obtained. The method has the prominent advantages the waste is turned into wealth, at the same time of reducing beta-tetra-O-acetyl-D-ribose crystalline residual liquid, the original waste alpha-tetra-O-acetyl-D-ribose is utilized, and the method has the obvious implement value and social and economic benefits.
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Paragraph 0094; 0095; 0096
(2017/05/27)
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- Anaerobic 5-Hydroxybenzimidazole Formation from Aminoimidazole Ribotide: An Unanticipated Intersection of Thiamin and Vitamin B12 Biosynthesis
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Comparative genomics of the bacterial thiamin pyrimidine synthase (thiC) revealed a paralogue of thiC (bzaF) clustered with anaerobic vitamin B12 biosynthetic genes. Here we demonstrate that BzaF is a radical S-adenosylmethionine enzyme that catalyzes the remarkable conversion of aminoimidazole ribotide (AIR) to 5-hydroxybenzimidazole (5-HBI). We identify the origin of key product atoms and propose a reaction mechanism. These studies represent the first step in solving a long-standing problem in anaerobic vitamin B12 assembly and reveal an unanticipated intersection of thiamin and vitamin B12 biosynthesis.
- Mehta, Angad P.,Abdelwahed, Sameh H.,Fenwick, Michael K.,Hazra, Amrita B.,Taga, Michiko E.,Zhang, Yang,Ealick, Steven E.,Begley, Tadhg P.
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supporting information
p. 10444 - 10447
(2015/09/28)
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- Molecular sieves mediated green per-O-acetylation of carbohydrate templates and lipase catalyzed regioselective alcoholysis of 2,3,5-Tri-O-acetyl-D-ribonolactone
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The per-O-acetylation of D-ribono-1,4-lactone and representative carbohydrates through the combination of acetic anhydride and molecular sieves under solvent-free conditions is demonstrated. The use of 13X/KCl molecular sieves as the heterogeneous catalyst was found to be more efficient than the excess of pyridine normally employed in the conventional method, giving high yields of the expected peracetylated product after 3 h at 25 °C or 1 h at 50 °C. The transformation can be carried out in gram scale and in an open flask. Additionally, the catalyst is readily separated from the reaction medium and can be reutilized without significant loss of activity. This green procedure for acetylation was extended to D-ribonolactone derivatives and natural carbohydrates. To demonstrate the synthetic utility of the method, 2,3,5-tri-O-acetyl-D-ribonolactone was selected as the substrate for the regioselective alcoholysis of acetyl group catalyzed by Candida antarctica lipase B in EtOH to selectively produce 2,3-di-O-acetyl-D-ribonolactone in gram scale.
- Cardozo, Herbert M.,Ribeiro, Thaís F.,Sá, Marcus M.,Sebr?o, Damianni,Nascimento, Maria G.,Silveira, Gustavo P.
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p. 755 - 764
(2015/04/14)
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- Sono-transition-metal catalysis of one-pot three-step synthesis of glycosyl-1,2,3-triazoles
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As a continuation of our studies directed at the development of straightforward and sustainable methodologies, we describe herein an original example of a combined effect of ultrasonic activation and iron-copper dual catalysis that allows an efficient and ecofriendly one-pot, three-step route to a new series of nucleoside-substituted triazoles. The reactions were carried out under both conventional and ultrasonic irradiation conditions. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- Driowya, Mohsine,Bougrin, Khalid,Benhida, Rachid
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supporting information
p. 1808 - 1817
(2013/05/22)
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- Design, synthesis and biological evaluation of azithromycin glycosyl derivatives as potential antibacterial agents
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A series of 11,12-cyclic carbonate azithromycin-4″-O-carbamoyl glycosyl derivatives were designed, synthesized, and evaluated as antibacterial agents to search for target compounds with excellent activity. The results of preliminary antibacterial tests against eight strains in vitro revealed that all of the title compounds exhibited improved activities with broad spectrum compared with the parent compound. The glycosylated side chains may be the pharmacophores responsible for the improved activity.
- Zhang, Lei,Chai, Xiaoyun,Wang, Baogang,Yu, Shichong,Hu, Honggang,Zou, Yan,Zhao, Qingjie,Meng, Qingguo,Wu, Qiuye
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p. 5057 - 5060
(2013/09/12)
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- Two-step synthesis of per-O-acetylfuranoses: Optimization and rationalization
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A simple two-step procedure yielding peracetylated furanoses directly from free aldoses was implemented. Key steps of the method are (i) highly selective formation of per-O-(tert-butyldimethylsilyl)furanoses and (ii) their clean conversion into acetyl ones without isomerization. This approach was easily applied to galactose and structurally related carbohydrates such as arabinose, fucose, methyl galacturonate and N-acetylgalactosamine to give the corresponding peracetylated targets. The success of this procedure relied on the control of at least three parameters: (i) the tautomeric equilibrium of the starting unprotected oses, (ii) the steric hindrance of both targeted furanoses and silylating agent, and finally, (iii) the reactivity of each soft nucleophile during the protecting group interconversion.
- Dureau, Remy,Legentil, Laurent,Daniellou, Richard,Ferrieres, Vincent
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p. 1301 - 1307
(2012/04/04)
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- Ultrasound-assisted one-pot synthesis of anti-CML nucleosides featuring 1,2,3-triazole nucleobase under iron-copper catalysis
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A simple and efficient synthesis of modified 1,2,3-triazole nucleosides was developed. The strategy involved sequential one-pot acetylation-azidation- cycloaddition procedure and was found to be highly effective under a cooperative effect of ultrasound activation and iron/copper catalysis. The reactions were carried out under both conventional and ultrasonic irradiation conditions. In general, improvement in rates and yields were observed when reactions were carried out under sonication compared with conventional conditions. This one-pot procedure provides several advantages such as operational simplicity, high yield, safety and environment friendly protocol. The resulting substituted nucleosides were evaluated for their anticancer activity against K562 chronic myelogenous leukemia (CML) cell line.
- Driowya, Mohsine,Puissant, Alexandre,Robert, Guillaume,Auberger, Patrick,Benhida, Rachid,Bougrin, Khalid
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experimental part
p. 1132 - 1138
(2012/08/29)
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- Enumeration of hydroxyl groups of sugars and sugar alcohols by aqueous-based acetylation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
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RATIONALE The properties of carbohydrates are determined in part by the number and stereochemical arrangement of their hydroxyl groups. To facilitate their analysis, rapid methods are needed to identify and enumerate hydroxyl groups in sugars and polyalcohols, especially methods that are water-based. METHODS The present report details the results of an alternative method for identification and enumeration of hydroxyl groups in aqueous media. It employs vinyl acetate to selectively derivatize hydroxyl groups in analytes, followed by analysis of the reaction mixtures by matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF-MS). RESULTS The method has been applied to several single and multi-component mixtures of monosaccharides and polyalcohols. The O-acetylated products were analyzed without chromatographic separation or purification by MALDI-TOF-MS. The mass spectra revealed consecutive ion peaks that are separated by 42 mass units as a consequence of displacement of one hydroxyl hydrogen by one acetyl group. CONCLUSIONS A rapid and aqueous-based method is described to enumerate the hydroxyl groups in carbohydrates. The number of ion peaks due to derivatized products is determined by MALDI-TOF-MS, and corresponds to the number of free hydroxyl groups in the analyte. The method is applicable to both single and multi-component mixtures. Published 2011. This article is a US Government work and is in the public domain in the USA. Published 2012. This article is a US Government work and is in the public domain in the USA.
- Adeuya, Anthony,Price, Neil P.J.
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experimental part
p. 1372 - 1376
(2012/08/08)
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- Synthesis of 5-deoxy-β-d-galactofuranosides as tools for the characterization of β-d-galactofuranosidases
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Derivatives of 5-deoxy-β-d-galactofuranose (5-deoxy-α-l-arabino- hexofuranose) have been synthesized starting from d-galacturonic acid. The synthesis of methyl 5-deoxy-α-l-arabino-hexofuranoside (14α) was achieved by an efficient strategy previously optimized, involving a photoinduced electron transfer (PET) deoxygenation. Compound 14α was converted into per-O-acetyl-5-deoxy-α,β-l-arabino-hexofuranoside (16), an activated precursor for glycosylation reactions. The SnCl4-promoted glycosylation of 16 led to 4-nitrophenyl (19α), and 4-methylthiophenyl 5-deoxy-α-l-arabino-hexofuranosides (20α). The oxygenated analog 4-methylphenyl 1-thio-β-d-galactofuranoside (23β) was also prepared. The 5-deoxy galactofuranosides were evaluated as inhibitors or substrates of the exo-β-d-galactofuranosidase from Penicillium fellutanum, showing that the absence of HO-5 drastically diminishes the affinity for the protein.
- Bordoni, Andrea,De Lederkremer, Rosa M.,Marino, Carla
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experimental part
p. 5339 - 5345
(2010/09/05)
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- Synthesis of a dimer of β-(1,4)-l-arabinosyl-(2 S,4 R)-4-hydroxyproline inspired by art v 1, the major allergen of mugwort
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Nα-tert-Butoxycarbonyl-l-trans-4-hydroxyproline allyl ester (Boc-Hyp-OAll) was glycosylated with 2,3,5-tri-O-benzyl-l-arabinose p-cresylthioglycoside in 60% yield with 4:1 β:α stereoselectivity. Deprotection of N- and C-terminii independently gave a prolyl amine and prolyl carboxylate respectively that were coupled under standard conditions with 1-[bis-(dimethylamino)methylene]-1H-1,2,3-triazolo-[4,5,b]-pyridininium hexafluorophosphate 3-oxide (N-HATU) to give the dimer 1 in 46% yield. These results represent the first steps toward the production of homogeneous oligomers to determine the minimal epitope of the Art v 1 allergen.
- Xie, Ning,Taylor, Carol M.
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supporting information; experimental part
p. 4968 - 4971
(2010/12/25)
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- Diastereoselective enzymatic preparation of acetylated pentofuranosides carrying free 5-hydroxyl groups
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Methyl 3-O-acetyl-2-deoxy-α-d-ribofuranoside, 1,3-di-O-acetyl-2-deoxy-α-d-ribofuranose and 1,2,3-tri-O-acetyl-α-d-arabinofuranose were diastereoselectively prepared (de = 100%) from anomeric mixtures of the corresponding 5-acetylated compounds through Can
- Gudino, Esteban D.,Iribarren, Adolfo M.,Iglesias, Luis E.
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experimental part
p. 1813 - 1816
(2009/12/26)
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- Studies toward the total synthesis of carba analogue of motif C of M. TB cell wall AG complex
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Herein we describe the synthesis of the carba analogue of motif C of arabinogalactan complex present in M. tuberculosis cell wall. Pd(0) catalyzed allylic alkylation and Fraser-Reid's glycosidation are the two key reactions that were employed for the synthesis of central glycosyl accepter unit and the glycosylation respectively.
- Gurjar, Mukund K.,Reddy, Challa Nageswar,Kalkote, Uttam R.,Chorghade, Mukund S.
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scheme or table
p. 909 - 925
(2010/10/20)
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- Lipase-catalyzed regio- and stereoselective deacylation: Separation of anomers of peracylated α,β-D-ribofuranosides
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Efficient regio- and stereoselective deacylation of acyloxy function involving C-5′ hydroxyl group of α-anomer over the other similar C-5′ acyl group of β-anomer and acyl groups involving secondary hydroxyls in anomeric mixture of peracylates of D-ribose has been achieved during deacylation reaction mediated by Lipozyme TL IM (Thermomyces lanuginosus lipase immobilized on silica). This enzymatic methodology has been efficiently used for the separation of anomeric mixtures of peracylated α,β-D-ribofuranosides.
- Sharma, Raman K.,Aggarwal, Neha,Arya, Anu,Olsen, Carl E.,Parmar, Virinder S.,Prasad, Ashok K.
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scheme or table
p. 1727 - 1731
(2011/03/19)
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- Vinyl acetate and sodium carbonate as a fast and efficient catalyst for per-O-acetylation of monosaccharides
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Vinyl acetate and sodium carbonate catalysed acetylation of several monosaccharides is an efficient synthesis of per-O-acetylation of carbohydrates and achieve the products in excellent yields and short reaction times. D-Glucose as the substrate in large scale also proceeds in high yield.
- Chen, Li,Zhang, Jianbo,Shi, Chunjuan,Wang, Xiaohu,Zhang, Bo,Tang, Jie
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experimental part
p. 380 - 382
(2009/06/18)
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- On the use of 3,5-O-benzylidene and 3,5-O-(Di-tert-butylsilylene)-2-O- benzylarabinothiofuranosides and their sulfoxides as glycosyl donors for the synthesis of β-arabinofuranosides: Importance of the activation method
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A 2-O-benzyl-3,5-O-benzylidene-α-D-thioarabinofuranoside was obtained by reaction of the corresponding diol with α,α-dibromotoluene under basic conditions. On activation with 1-benzenesulfinyl piperidine, or diphenyl sulfoxide, and trifluoromethanesulfonic anhydride in dichloromethane at -55 °C, reaction with glycosyl acceptors affords anomeric mixtures with little or no selectivity. The analogous 2-O-benzyl-3,5-O-(di-tert-butylsilylene)- α-D-thioarabinofuranoside also showed no significant selectivity under the 1-benzenesulfinyl piperidine or diphenyl sulfoxide conditions. With N-iodosuccinimide and silver trifluoromethanesulfonate the silylene acetal showed moderate to high β-selectivity, independent of the configuration of the starting thioglycoside. High β-selectivity was also obtained with a 2-O-benzyl-3,5-O-(di-tert-butylsilylene)-α-arabinofuranosyl sulfoxide donor on activation with trifluoromethanesulfonic anhydride. The high β-selectivities obtained by the N-iodosuccinimide/silver trifluoromethanesulfonate and sulfoxide methods are consistent with a common intermediate, most likely to be the oxacarbenium ion. The poor selectivity observed on activation of the thioglycosides with the 1-benzenesulfinyl piperidine, or diphenyl sulfoxide, and trifluoromethanesulfonic anhydride methods appears to be the result of the formation of a complex mixture of glycosyl donors, as determined by low-temperature NMR work.
- Crich, David,Pedersen, Christian Marcus,Bowers, Albert A.,Wink, Donald J.
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p. 1553 - 1565
(2007/10/03)
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- TRANSACETALISATION PROCESS
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The invention relates to the resolution of racemic mixtures, and in particular to the separation of enantiomers of chiral alcohols utilising recyclable chiral auxiliaries. The present invention also relates to a process for preparing these recyclable chiral auxiliaries using an enantiomerically pure alcohol.
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Page/Page column 40-41
(2010/02/13)
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- A method for obtaining equilibrium tautomeric mixtures of reducing sugars via glycosylamines using nonaqueous media
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Equilibrium tautomeric mixtures of several mono- and disaccharides are obtained in anhydrous form, without the use of water, by reacting the commercially available reducing sugars with ammonia gas in dry methanol, followed by the concentration of the resultant solution to dryness. Mutarotation and hydrolysis of the initially formed glycosylamine in the resultant medium account for the transformation. Equilibrium anomeric mixtures enriched in the β-form of commercially available sugars such as α-D-glucose and α-lactose have not only vastly increased solubility, but are also synthetically valuable as these can be readily converted to the methyl/benzyl/trimethylsilyl ether and other derivatives for further transformations.
- Allavudeen, Sikkander Sulthan,Kuberan, Balagurunathan,Loganathan, Duraikkannu
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p. 965 - 968
(2007/10/03)
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- The arabinofuranoside method, a convenient substitute of the fucofuranoside method for determining the absolute configuration of the secondary alcohols
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As a simple substitute of the fucofuranoside method, a recently devised technique for determining the absolute configuration of secondary alcohols by 13C NMR, the arabinofuranoside method is proposed. Unlike fucose, the derivatizing agent arabi
- Kobayashi, Masaru
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p. 9365 - 9371
(2007/10/03)
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- The influence of boric acid on the acetylation of aldoses: 'One-pot' syntheses of penta-O-acetyl-β-D-glucofuranose and its crystalline propanoyl analogue
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When glucose and boric acid are heated in acetic acid a soluble compound forms from which, with acetic anhydride and catalytic amounts of sulfuric acid, a mixture consisting of >90% of the glucofuranose per-acetates (α : β ratio 1 : 1.8) is obtained in high yield. In the absence of the sulfuric acid partial acetylation takes place and penta-O-acetyl-β-D-glucofuranose (α: β ratio 1 : 52) is obtainable in good yield by removal of boric acid and completion of the esterification by addition of acetic anhydride and pyridine. A new, crystalline glucofuranose, penta-O-propanoyl-β-D-glucofuranose, is obtained in 58% yield in a 'one-pot' procedure using boric acid. The effects of boric acid on the acid-catalysed acetylation of other aldo-hexoses and -pentoses suggest that the synthesis of furanosyl per-esters could be successful with xylose and idose as well as with glucose.
- Furneaux, Richard H.,Rendle, Phillip M.,Sims, Ian M.
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p. 2011 - 2014
(2007/10/03)
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- H-Beta zeolite as an efficient catalyst for per-O-acetylation of mono- and disaccharides
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Among the six different zeolites examined, H-beta is demonstrated to be a highly efficient and selective catalyst for the per-O-acetylation of various mono-and disaccharides and methyl glycosides.
- Bhaskar, Pallooru Muni,Loganathan, Duraikkannu
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p. 129 - 131
(2007/10/03)
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- Per-O-acetylation of sugars catalysed by montmorillonite K-10
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The inexpensive solid acid, montmorillonite K-10, is shown to be an efficient catalyst for the per-O-acetylation of several mono-, di- and trisaccharides. The pyranose forms accounted for 75- 100% of the acetylated products.
- Bhaskar, Pallooru Muni,Loganathan, Duraikkannu
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p. 2215 - 2218
(2007/10/03)
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- Process for preparing 2',3',5'-tri-0-acetyl-6-azauridine
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Process for preparing 2',3',5'-tri-0-acetyl-6-azauridine having the following formula SPC1 Which comprises reacting a crude anomeric mixture of methyl D-ribofuranosides having the formula SPC2 With anhydrous hydrogen chloride or anhydrous hydrogen bromide in the presence of acetic anhydride and acetic acid to thereby form the corresponding 2,3,5-tri-0-acetyl-D-ribofuranosyl halide having the formula SPC3 Wherein X is chloro or bromo, reacting the halide of formula III with 3,5-bis-trimethylsilyloxy-1,2,4-triazine having the following formula SPC4 In the presence of an inert solvent and a mercuric halide and recovering the 2',3',5'-tri-0-acetyl-6-azauridine.
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