Synthesis of (±)-1,2,3-triazolo-3′-deoxy-4′-hydroxymethyl carbanucleosides via ‘click’ cycloaddition

Conformationally Locked Carbocyclic Nucleosides Built on a 4'-Hydroxymethyl-3'-hydroxybicyclo[4.1.0]heptane Template. Stereoselective Synthesis and Antiviral Activity

Two new families of enantiomerically pure carbocyclic nucleoside analogues based on a cyclohexane moiety with five chiral centers and a fused cyclopropyl ring have been synthesized. A highly regio- and stereoselective synthetic approach for the modular construction of the functionalized bicyclo[4.1.0]heptyl azide intermediate 6 has been established. Key steps to achieve this asymmetric synthesis involved highly diastereoselective allylic oxidation and hydroboration reactions. The first family of compounds, 1a,b and 2, presents different natural nucleobases, whereas the second one 3a-e bears functionalized 1,2,3-triazoles. These derivatives have been tested as antiviral agents, and compound 3d has shown to display moderate activity against coxsackie B4 virus.

Chemical Approaches to Carbocyclic Nucleosides

Nucleoside analogues are at the forefront of antiviral therapy for last decades. To circumvent some of their limitations, based on their metabolism, and in order to improve their anti-viral potency and selectivity, several families of nucleoside analogues have been described through structural modifications at the sugar and heterocycles. The replacement of the oxygen of the nucleoside by a methylene has led to the family of carbocyclic (or cyclopentane) nucleoside analogues. Various potent anti-HIV and anti-HBV drugs belong to this family. Main syntheses of carbocyclic analogues of nucleosides used Diels-Alder reactions (in racemic or asymmetric series), but also started from carbohydrates (ribose, glucose), as a source of optically active compounds, which then had to be transformed into carbacycles under various conditions. The growing interest in carbocyclic nucleosides has led several groups, including ours, to develop new analogues and to explore novel routes. This article will review some of the recent chemistry developed on selected five-membered ring carbocyclic nucleosides.

Efficient and selective azidation of per-O-acetylated sugars using ultrasound activation: application to the one-pot synthesis of 1,2,3-triazole glycosides

A new protocol was developed for the selective transformation of acetyl-sugars to triazolyl nucleosides using in situ generated SO₂(N₃)₂, iron/copper cocatalysis and ultrasound activation.

A family of unsymmetrical hydroxyl-substituted BEDT-TTF donors: syntheses, structures and preliminary thin film studies

Synthetic routes to three novel OH-functionalized BEDT-TTF donorsH1–H3are presented. Charge transfer salts ofH1and2and polystyrene blend thin films ofH3have been studied after doping with iodine.

Synthesis of new 1,2,3-triazol-4-yl-quinazoline nucleoside and acyclonucleoside analogues

In this study, we describe the synthesis of 1,4-disustituted-1,2,3-triazolo-quinazoline ribonucleosides or acyclonucleosides by means of 1,3-dipolar cycloaddition between various O or N-alkylated propargyl-quinazoline and 1'-azido-2',3',5'-tri-O-benzoylribose or activated alkylating agents under microwave conditions. None of the compounds selected showed significant anti-HCV activity in vitro.

A review of methods to synthesise 4′-substituted nucleosides

Modified nucleosides have received a great deal of attention from the scientific community, either for use as therapeutic agents, diagnostic tools, or as molecular probes.

Ultrasound-assisted one-pot synthesis of anti-CML nucleosides featuring 1,2,3-triazole nucleobase under iron-copper catalysis

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.

Microwave-assisted syntheses of nucleosides and their precursors

In recent decades, nucleosides analogs have been the cornerstone in the treatment of various diseases, such as AIDS, herpes and hepatitis. More than 40 modified nucleosides are officially approved by the US FDA and represent the major compound class for inhibition of viral replication. By comparison with traditional conditions, microwave irradiation offers a powerful tool that can increase yields and decrease reaction time, with simple manipulation and an environmentally friendly way. Here, we report the latest progress in nucleoside synthesis using microwave irradiation.

Synthesis and anti-HIV evaluation of 3'-triazolo nucleosides

A series of hitherto unknown 3'-α-[1,2,3]-substituted triazolo-2',3'-dideoxypyrimidine nucleoside analogues of the anti-HIV 3'-azido-3'-deoxythymidine (AZT) were synthesized through catalyzed alkyne-azide 1,3-dipolar cycloaddition (Huisgen reaction). Those 3'-[1,2,3]-triazolo analogues bearing an azido alkyl chain were evaluated for their anti-HIV activity against HIV-1 in primary human lymphocytes as well as for their cytotoxicity in different cells. None of them inhibit HIV replication (EC(50) > 20 μM); two of them were converted to their triphosphate form to evaluate their HIV-RT inhibition.

Synthesis of new C5-(1-substituted-1,2,3-triazol-4 or 5-yl)-2'-deoxyuridines and their antiviral evaluation

The synthesis and antiviral evaluation of a series of C5-(1,4- and 1,5-disubstituted-1,2,3-triazolo)-nucleoside derivatives is described. The key steps of this synthesis are regioselective Huisgen's 1,3-dipolar cycloaddition, using either copper-catalyzed azide-alkyne cycloaddition (CuAAC) or ruthenium-catalyzed azide-alkyne cycloaddition (RuAAC) under microwave activation. Some compounds among the 5a-l series possess activity against herpes simplex viruses 1 and 2, varicella-zoster virus, human cytomegalovirus and vaccinia virus. Their cytostatic activities were determined against murine leukemia cells, human T-lymphocyte cells and cervix carcinoma cells. Compounds were also evaluated on a wide panel of RNA viruses, including Vesicular stomatitis virus, influenza viruses type A (H1N1 and H3N2) and B in MDCK cell cultures, parainfluenza-3 virus, reovirus-1, Sindbis virus and Punta Toro virus in Vero cell cultures and Vesicular stomatitis, Coxsackie B4 and respiratory syncytial virus, with no specific antiviral effect.

Synthesis and antitumor activity of novel 2',3'-diethanethio-2',3',5'-trideoxy-5'-triazolonucleoside analogues

A series of novel 2',3'-diethanethio-2',3',5'-trideoxy-5'-triazoloribonucleosides was synthesized in excellent yields and their antitumor activity was evaluated. These nucleoside analogues with aromatic substituted triazole rings showed significantly improved activity towards a broad range of tumor cell lines and those without arene substitutes were inactive.