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

Recent Progress on Synthesis of Functionalized 1,5-Disubstituted Triazoles

Immediately after the invention of 'Click Chemistry' in 2002, the regioselective 1,2,3- triazole scaffolds resulted from respective organic azides and terminal alkynes under Cu(I) catalysis have been well recognized as the functional heterocyclic core at the centre of modern organic chemistry, medicinal chemistry, and material sciences. This CuAAC reaction has several notable features including excellent regioselectivity, high-to-excellent yields, easy to execute, short reaction time, modular in nature, mild condition, readily available starting materials, etc. Moreover, the resulting regioselective triazoles can serve as amide bond isosteres, a privileged functional group in drug discovery and development. More than hundreds of reviews had been devoted to the 'Click Chemistry' in special reference to 1,4-disubstituted triazoles, while only little efforts were made for an opposite regioisomer i.e., 1,5-disubstituted triazole. Herein, we have presented various classical approaches for an expeditious synthesis of a wide range of biologically relevant 1,5- disubstituted 1,2,3-triazole analogues. The syntheses of such a class of diversly functionalized triazoles have emerged as a crucial investigation in the domain of chemistry and biology. This tutorial review covers the literature assessment on the development of various synthetic protocols for the functionalized 1,5-disubstituted triazoles reported during the last 12 years.

Towards Anticancer and Antibacterial Agents: Design and Synthesis of 1,2,3-Triazol-quinobenzothiazine Derivatives

In this paper, we describe a new method for synthesizing hybrid combinations of 1,2,3-triazoles with a tetracyclic quinobenzothiazinium system. The developed approach allowed for the production of a series of new azaphenothiazine derivatives with the 1,2,3-triazole system in different positions of the benzene ring. In practice, the methodology consists of the reaction of triazole aniline derivatives with thioquinanthrenediinium bis-chloride. The structure of the products was determined by 1H-NMR, 13C-NMR spectroscopy, and HR-MS spectrometry, respectively. Moreover, the spatial structure of the molecule and the arrangement of molecules in the crystal (unit cell) were determined by X-ray crystallography. The anticancer activity profiles of the synthesized compounds were tested in vitro against human cancer cells of the A549, SNB-19, and T47D lines and the normal NHDF cell line. Additional tests of antibacterial activity against methicillin-sensitive and methicillin-resistant staphylococci, vancomycin-sensitive and vancomycin-resistant enterococci, and two mycobacterial strains were also performed. In fact, the dependence of anticancer and antibacterial activity on the substituent type and its position in the quinobenzothiazinium system was observed. Furthermore, the distance-guided property evaluation was performed using principal component analysis (PCA) and hierarchical clustering analysis (HCA) on the pool of the calculated descriptors. Finally, the theoretically approximated partition coefficients (clogP) were (inter-)correlated with each other and cross-compared with the empirically specified logPTLC parameters.

Synthesis and Antiviral Evaluation of Nucleoside Analogues Bearing One Pyrimidine Moiety and Two D-Ribofuranosyl Residues

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.

Synthesis of 1,2,3-triazolyl nucleoside analogues and their antiviral activity

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

Electronic supplementary material

The online version of this article (10.1007/s11030-020-10141-y) contains supplementary material, which is available to authorized users.

Cycloaddition reactions for antiviral compounds

Prominent in the current stage of drug development, antiviral compounds can be efficiently prepared through cycloaddition reactions. The chapter reports the use of classical Diels–Alder and their hetero version for the design and synthesis of compounds that were tested for their antiviral activities against a variety of viruses. Furthermore, 1,3-dipolar cycloaddition reactions of selected 1,3-dipoles, such as azides, nitrones, and nitrile oxides, are reviewed in the light of their application in the preparation of key intermediates for antiviral synthesis. A few examples of [2+2] cycloaddition reactions are also presented. The products obtained from these pericyclic reaction approaches were all tested for their activities in terms of blocking the virus replication, and the relevant biological data are highlighted.

Quinoline-triazole hybrids inhibit falcipain-2 and arrest the development ofPlasmodium falciparumat the trophozoite stage

The present study involves development of novel quinoline triazole-containing cysteine protease inhibitors which arrest the development ofP. falciparumat the trophozoite stage.

Design, Synthesis and Cytotoxic Evaluation of 4-Anilinoquinazoline– triazole–AZT Hybrids as Anticancer Agents

A series of 4-anilinoquinazoline–triazole–AZT hybrids were designed and synthesized as anticancer agents. Their cytotoxic potential has been evaluated by means of a micro-dilution assay against three human cancer cell lines (KB, epidermoid carcinoma; HepG2, hepatoma carcinoma; SK-Lu-1, non-small lung cancer). The biological results revealed that compounds 4b and 6d showed good anticancer activities against KB, HepG2, and Lu cell lines (IC50 values ranging from 9 μM to 100 μM). Especially, compounds 4b and 6d exhibited up to 3-fold more potent than reference drugs erlotinib hydrochloride and AZT in term of anti-lung cancer activity.

Synthesis, Antiviral, and Antimicrobial Evaluation of Benzyl Protected Diversified C-nucleosides

Formyl glycals are the versatile synthetic intermediates and can serves as precursor for the synthesis of various C and N-nucleosides. Due to the presence of electron donating and electron withdrawing character on formyl sugars which makes the molecule more susceptible to nucleophilic attack. Utilizing same strategy, we propose the synthesis of diversified C-nucleosides (3-14) by reaction with N,N dinucleophiles. These nucleoside analogs were than tested against viral, bacterial and fungal strains.

NCN-Coordinating Ligands based on Pyrene Structure with Potential Application in Organic Electronics

Five novel derivatives of pyrene, substituted at positions 1,3,6,8 with 4-(2,2-dimethylpropyloxy)pyridine (P1), 4-decyloxypyridine (P2), 4-pentylpyridine (P3), 1-decyl-1,2,3-triazole (P4), and 1-benzyl-1,2,3-triazole (P5), are obtained through a Suzuki-Miyaura cross-coupling reaction or Cu^I -catalyzed 1,3-dipolar cycloaddition reaction, respectively, and characterized thoroughly. TGA measurements reveal the high thermal stability of the compounds. Pyrene derivatives P1-P5 all show photoluminescence (PL) quantum yields (Φ) of approximately 75 % in solution. Solid-state photo- and electroluminescence characteristics of selected compounds as organic light-emitting diodes are tested. In the guest-host configuration, two matrixes, that is, poly(N-vinylcarbazole) (PVK) and a binary matrix consisting of PVK and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (50:50 wt %), are applied. The diodes show red, green, or blue electroluminescence, depending on both the compound chemical structure and the actual device architecture. In addition, theoretical studies (DFT and TD-DFT) provide a deeper understanding of the experimental results.

Novel pyrimidine-2,4-dione-1,2,3-triazole and furo[2,3-d]pyrimidine-2-one-1,2,3-triazole hybrids as potential anti-cancer agents: Synthesis, computational and X-ray analysis and biological evaluation

Regioselective 1,4-disubstituted 1,2,3-triazole tethered pyrimidine-2,4-dione derivatives (5-23) were successfully prepared by the copper(I)-catalyzed click chemistry. While known palladium/copper-cocatalyzed method based on Sonogashira cross-coupling followed by the intramolecular 5-endo-dig ring closure generated novel 6-alkylfuro[2,3-d]pyrimidine-2-one-1,2,3-triazole hybrids (24b-37b), a small library of their 5-alkylethynyl analogs (24a-37a) was synthesized and described for the first time by tandem terminal alkyne dimerization and subsequent 5-endo-trig cyclization, which was additionally corroborated with computational and X-ray crystal structure analyses. The nature of substituents on alkynes and thereof homocoupled 1,3-diynes predominantly influenced the ratio of the formed products in both pathways. In vitro antiproliferative activity of prepared compounds evaluated on five human cancer cell lines revealed that N,N-1,3-bis-(1,2,3-triazole)-5-bromouracil (5-7) and 5,6-disubstituted furo[2,3-d]pyrimidine-2-one-1,2,3-triazole 34a hybrids exhibited the most pronounced cytostatic acitivities against hepatocellular carcinoma (HepG2) and cervical carcinoma (HeLa) cells with higher potencies than the reference drug 5-fluorouracil. Cytostatic effect of pyrimidine-2,4-dione-1,2,3-triazole hybrid 7 in HepG2 cells could be attributed to the Wee-1 kinase inhibition and abolishment of sphingolipid signaling mediated by acid ceramidase and sphingosine kinase 1. Importantly, this compound proved to be a non-mitochondrial toxicant, which makes it a promising candidate for further lead optimization and development of a new and more efficient agent for the treatment of hepatocellular carcinoma.

Synthesis and Antimicrobial Screening of Novel Thioglycosides and Acyclonucleoside Analogs Carrying 1,2,3-Triazole and 1,3,4-Oxadiazole Moieties

The solvent-free 1,3-dipolar cycloaddition reaction of dimethylacetylene dicarboxylate (1) with 2-chlorophenyl azide (2) afforded 1,2,3-triazole diester 3 that upon hydrazinolysis, furnished the corresponding bis-acid hydrazide 4. The treatment of compound 4 with carbon disulfide in a refluxing potassium hydroxide solution furnished the desired bis-1,3,4-oxadiazole-2-thione 5 tethered to a 1,2,3-triazole moiety. The respective SOx-glycosides 9-11 were obtained by glycosylation of bis-oxadiazole 5 with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide (6), 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide (7), and 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl chloride (8) in dry acetone in the presence of Et3N, which acted as a base. However, alkylation of 5 with halogeno-alkanol 12 or 13, chloroglycerol 14, bromoethers 20 or 21, and epichlohydrin 22 in the presence of K2CO3 in DMF yielded the corresponding acyclonucleoside analogs 16-18 and 23-25. The isopropylidenes 19 and acetyl derivatives 26-28 of the products were also prepared. The newly synthesized compounds were characterized by (1)H NMR, (13)C NMR, 2D NMR, and mass spectra. The compounds were screened for their antibacterial and antifungal activities. A number of the tested compounds exhibited significant antimicrobial activity compared to the reference drugs.

Synthesis of new C-5-triazolyl-functionalized thymidine analogs and their ability to engage in aromatic stacking in DNA : DNA and DNA : RNA duplexes

Stacking interactions of substituted triazoles in the major groove were studied, and with a polar uracil, increased duplex stabilities were found.

Discovery of New Acid Ceramidase-Targeted Acyclic 5-Alkynyl and 5-Heteroaryl Uracil Nucleosides

A series of novel N-acyclic uracil analogs with linear, branched, aromatic, and cyclopropyl-alkynyl as well as heteroaryl moieties at C-5 were prepared using palladium catalyzed Sonogashira and Stille cross-coupling and evaluated against malignant tumor cell lines. C-5-Furan-2-yl uracil derivative 6 was shown to be more potent against MCF-7 than the reference drug 5-fluorouracil (5-FU), while C-5-alkynyl uracil derivatives 9c and 9e exhibited antibreast cancer activities comparable to 5-FU. Selected compounds induced cell death, partially due to apoptosis, of MCF-7 breast cancer cells. Abrogation of acid ceramidase (ASAH1) expression of 9c and 9e indicated that these compounds could perturb ASAH1-mediated sphingolipid signaling. The selective activity of 9c and 9e against breast cancer cells via the ASAH1-mediated signaling, as a molecular target, might have a great advantage for potential future therapeutic use.

Design and synthesis of 2'-deoxy-2'-[(1,2,3)triazol-1-yl]uridines using click chemistry approach

A series of novel nucleosides bearing a 1,2,3-triazole moiety at the 2'-position of the sugar moiety has been synthesized starting from 2'-azidouridine and using the copper (I)-catalyzed Huisgen-Sharpless-Meldal 1,3-dipolar cycloaddition reaction. The reactions proceeded in overall yield of 52-82% and gave almost exclusively the 1,4-disubstituted 1,2,3-triazoles. The 2'-azidouridine was synthesized from uridine in two steps, and reacted with a variety of differently substituted alkynes to give the desired 2'-triazole-substituted uridine derivatives.

Chemoenzymatic synthesis of 3'-deoxy-3'-(4-substituted-triazol-1-YL)-5-methyluridine

An efficient protocol has been developed for the synthesis of a small library of 3'-deoxy-3'-(4-substituted-triazol-1-yl)-5-methyluridine using Cu(I)-catalyzed Huisgen-Sharpless-Meldal 1,3-dipolar cycloaddition reaction of 3'-azido-3'-deoxy-5-methyluridine with different alkynes under optimized condition in an overall yields of 76%-92%. Here, the azido precursor compound, i.e., 3'-azido-3'-deoxy-5-methyluridine was chemoenzymatically synthesized from D-xylose in good yield. Some of the alkynes used in cycloaddition reaction were synthesized by the reaction of hydroxycoumarins or naphthols with propargyl bromide in acetone using K2CO3in excellent yields. All synthesized compounds were unambiguously identified on the basis of their spectral (IR, (1)H-, (13)C NMR spectra, and high-resolution mass spectra) data analysis.

Design, synthesis, antiviral and cytotoxic evaluation of novel acyclic phosphonate nucleotide analogues with a 5,6-dihydro-1H-[1,2,3]triazolo[4,5-d]pyridazine-4,7-dione system

ABSTRACT

A series of diethyl 2-(4,5-dimethoxycarbonyl-1H-1,2,3-triazol-1-yl)alkylphosphonates was synthesised from ω-azidoalkylphosphonates and dimethyl acetylenedicarboxylate and was further transformed into the respective diamides, dihydrazides, and 5,6-dihydro-1H-[1,2,3]triazolo[4,5-d]pyridazine-4,7-diones as phosphonate analogues of acyclic nucleosides having nucleobases replaced with substituted 1,2,3-triazoles. All compounds containing P-C-C-triazole or P-C-C-CH2-triazole moieties exist in single conformations in which the diethoxyphosphoryl and substituted 1,2,3-triazolyl or substituted (1,2,3-triazolyl)methyl groups are oriented anti. All phosphonates were evaluated in vitro for activity against a variety of DNA and RNA viruses. None of the compounds were endowed with antiviral activity. They were not cytostatic at 100 μM.

GRAPHICAL ABSTRACT

Synthesis of some new benzisothiazolone and benzenesulfonamide derivatives of biological interest starting from saccharin sodium

Two new series of benzenesulfonamide (4a-f, 5a-b, 6, 7) and 1,2-benzisothiazol-3(2H)-one-1,1-dioxide (9a-c, 10, 12a-d) derivatives were prepared starting from saccharin sodium. The novel compounds were characterized using elemental analyses and different spectroscopic methods. Assessment of the antiviral activities of these novel compounds against a broad panel of viruses in different cell cultures revealed that only the thiazole derivatives belonging to the benzisothiazol-3(2H)-one-1,1-dioxide series are the active ones. All thiazole derivatives 12a-d showed activity against both varicella-zoster virus, especially TK(-) VZV strain 07-1, and the cytomegalovirus strains AD-169 and Davis in human embryonic lung (HEL) cell culture.

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.

Efficient one-pot synthesis of polysubstituted 6-[(1H-1,2,3-triazol-1-yl)methyl]uracils through the “click” protocol

The preparation of several triazolo acyclic nucleosides and triazolo acyclic nucleoside phosphonates is described. The synthetic methodology has been developed as an efficient one-pot Cu(I)-catalyzed azide alkyne Huisgen “click” cycloaddition. A novel Cu(I)-catalyzed decarboxylation reaction of 1-substituted 1H-1,2,3-triazole-4-carboxylic acids at room temperature was observed and used for the preparation of 1-substituted 1H-1,2,3-triazoles. As congeners of TPI (Taiho pharmaceutical inhibitor), the prepared compounds were screened as potential inhibitors of human thymidine phosphorylase, but no inhibitory activity was observed.