Synthesis of 1,2,3-triazolo-nucleosides via the post-triazole N-alkylation

A review of click chemistry in the synthesis of organophosphorus triazoles and their biological activities

Organophosphorus compounds, characterized by the incorporation of phosphorus into organic molecules, play a critical role in various fields such as medicine, agriculture, and industry. Their unique electronic properties and versatility make them essential in developing therapeutic agents, pesticides, and materials. One prominent class of organophosphorus compounds is organophosphorus heterocycles, which combine the benefits of both phosphorus and cyclic structures. Triazoles, a class of nitrogen-containing heterocyclic compounds, are particularly notable for their broad biological activities, including anticancer, antiviral, antibacterial, and antioxidant effects. Traditional methods for synthesizing triazoles often encounter challenges such as low yields and non-selective products, whereas click chemistry provides a more efficient and reliable alternative. The copper-catalyzed azide-alkyne [3 + 2] cycloaddition, a cornerstone of click chemistry, allows for the rapid and selective formation of triazoles under mild conditions. When functionalized with organophosphorus groups, triazoles not only retain but often enhance their biological activities, improving their potency, selectivity, and stability. This review covers the synthesis of organophosphorus-functionalized triazoles via click chemistry and explores their molecular structure, including the coordination chemistry of these compounds. The behavior and interactions of these organophosphorus derivatives with various metal ions are also addressed, as these interactions significantly influence their chemical reactivity, stability, and bioactivity.

Crystal structure and Hirshfeld surface analysis of 4-azido-2-(3,5-di-methyl-phen-yl)-5-(4-nitro-phen-yl)-2H-1,2,3-triazole

In the title compound, C16H13N7O2, the 3,5-di-methyl-phenyl and 4-nitro-phenyl rings are inclined to the central 2H-1,2,3-triazole ring by 1.80 (7) and 1.79 (7)°, respectively, and to one another by 2.16 (7)°. In the crystal, the mol-ecules are linked by C-H⋯N hydrogen bonds and π-π stacking inter-actions [centroid-to-centroid distances = 3.7295 (9) and 3.7971 (9) Å], forming ribbons along the b-axis direction. These ribbons are connected to each other by weak van der Waals inter-actions and the stability of the crystal structure is ensured. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (31.5%), N⋯H/H⋯N (19.2%), O⋯H/H⋯O (14.5%), N⋯C/C⋯C (10.9%) and C⋯H/H⋯C (10.2%) contacts.

Synthesis of Tris-Heterocycles via a Cascade IMCR/Aza Diels-Alder + CuAAC Strategy

6-Triazolylmethyl-pyrrolo[3,4-b]pyridin-5-one tris-heterocycles were synthesized in 43-57% overall yields. The two-stage synthesis involved a cascade process (Ugi-3CR/aza Diels-Alder/N-acylation/aromatization) followed by a copper-assisted alkyne-azide [3+2] cycloaddition (CuAAC). This efficient and convergent strategy proceeded via complex terminal alkynes functionalized with a fused bis-heterocycle at the α-position. The final products are ideal candidates for SAR studies as they possess two privileged scaffolds in medicinal chemistry: 4-substituted or 1,4-substituted 1H-1,2,3-triazoles and pyrrolo[3,4-b]pyridin-5-ones.

Compounds based on 5-(perylen-3-ylethynyl)uracil scaffold: High activity against tick-borne encephalitis virus and non-specific activity against enterovirus A

Rigid amphipathic fusion inhibitors (RAFIs) are potent antivirals based on a perylene core linked with a nucleoside moiety. Sugar-free analogues of RAFIs, 5-(perylen-3-ylethynyl)uracil-1-acetic acid 1 and its amides 2, were synthesized using combined protection group strategy. Compounds 1 and 2 appeared to have low toxicity on porcine embryo kidney (PEK) or rhabdomiosarcoma (RD) cells together with remarkable activity against enveloped tick-borne encephalitis virus (TBEV): EC₅₀ values vary from 0.077 μM to subnanomolar range. Surprisingly, 3-pivaloyloxymethyl (Pom) protected precursors 7 and 8 showed even more pronounced activity. All the compounds showed no activity against several non-enveloped enteroviruses, except 4-hydroxybutylamides 2d,g, which inhibited the reproduction of enterovirus A71 with EC₅₀ 50-100 μM, with a non-specific mode of action. The results suggest that the carbohydrate moiety of RAFI nucleosides does not play a crucial role in their antiviral action, and biological activity of the 5-(perylen-3-ylethynyl)uracil scaffold can be effectively modulated by substituents in positions 1 and 3. The high antiviral activity of these new compounds, coupled with low toxicity advocate their potential role in antiviral therapy.

Design, synthesis, antiviral and cytostatic activity of ω-(1H-1,2,3-triazol-1-yl)(polyhydroxy)alkylphosphonates as acyclic nucleotide analogues

The efficient synthesis of a new series of polyhydroxylated dibenzyl ω-(1H-1,2,3-triazol-1-yl)alkylphosphonates as acyclic nucleotide analogues is described starting from dibenzyl ω-azido(polyhydroxy)alkylphosphonates and selected alkynes under microwave irradiation. Selected O,O-dibenzylphosphonate acyclonucleotides were transformed into the respective phosphonic acids. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses and for cytostatic activity against murine leukemia L1210, human T-lymphocyte CEM and human cervix carcinoma HeLa cells. Compound (1S,2S)-16b exhibited antiviral activity against Influenza A H3N2 subtype (EC50=20μM-visual CPE score; EC50=18μM-MTS method; MCC >100μM, CC50 >100μM) in Madin Darby canine kidney cell cultures (MDCK), and (1S,2S)-16k was active against vesicular stomatitis virus and respiratory syncytial virus in HeLa cells (EC50=9 and 12μM, respectively). Moreover, compound (1R,2S)-16l showed activity against both herpes simplex viruses (HSV-1, HSV-2) in HEL cell cultures (EC50=2.9 and 4μM, respectively) and feline herpes virus in CRFK cells (EC50=4μM) but at the same time it exhibited cytotoxicity toward uninfected cell (MCC⩾4μM). Several other compounds have been found to inhibit proliferation of L1210, CEM as well as HeLa cells with IC50 in the 4-50μM range. Among them compounds (1S,2S)- and (1R,2S)-16l were the most active (IC50 in the 4-7μM range).

ZrO2-supported Cu(ii)–β-cyclodextrin complex: construction of 2,4,5-trisubstituted-1,2,3-triazoles via azide–chalcone oxidative cycloaddition and post-triazole alkylation

The ZrO₂–Cu₂–β-CD complex is an excellent catalyst for the synthesis of N-2-alkylated-1,2,3-triazoles.

The synthesis, antiviral, cytostatic and cytotoxic evaluation of a new series of acyclonucleotide analogues with a 1,2,3-triazole linker

The efficient synthesis of a new series of acyclonucleotide analogues with a 1,2,3-triazole linker is described starting from diethyl azidomethyl-, 2-azidoethyl-, 3-azidopropyl-, 4-azidobutyl-, 2-azido-1-hydroxyethyl-, 3-azido-2-hydroxypropyl- and 3-azido-1-hydroxypropylphosphonates and selected alkynes under microwave irradiation. Several O,O-diethylphosphonate acyclonucleotides were transformed into the respective phosphonic acids. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses and cytostatic activity against murine leukaemia L1210, human T-lymphocyte CEM and human cervix carcinoma HeLa cells. Acyclonucleotide 22e exhibited activity against both herpes simplex viruses (HSV-1, HSV-2) in HEL cell cultures (EC₅₀ = 17 μM) and feline herpes virus (EC₅₀ = 24 μM) in CRFK cell cultures, while compounds 20k, 21k, 22k and 23k preferentially inhibited proliferation of human T-lymphocyte CEM cells at IC₅₀ in the 2.8–12 μM range.

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Nucleotide analogues with aliphatic linker between phosphorus and 1,2,3-triazole.

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Efficient synthesis of 1,2,3-triazole analogues of nucleotides.

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Antiviral activity and inhibitory effect on the proliferation of CEM cells.

Chemical architecture and applications of nucleic acid derivatives containing 1,2,3-triazole functionalities synthesized via click chemistry

There is considerable attention directed at chemically modifying nucleic acids with robust functional groups in order to alter their properties. Since the breakthrough of copper-assisted azide-alkyne cycloadditions (CuAAC), there have been several reports describing the synthesis and properties of novel triazole-modified nucleic acid derivatives for potential downstream DNA- and RNA-based applications. This review will focus on highlighting representative novel nucleic acid molecular structures that have been synthesized via the “click” azide-alkyne cycloaddition. Many of these derivatives show compatibility for various applications that involve enzymatic transformation, nucleic acid hybridization, molecular tagging and purification, and gene silencing. The details of these applications are discussed. In conclusion, the future of nucleic acid analogues functionalized with triazoles is promising.