Structural studies on bioactive compounds. Part 36: design, synthesis and biological evaluation of pyrimethamine-based antifolates against Pneumocystis carinii

A practical flow synthesis of 1,2,3-triazoles

A robust and versatile protocol for synthesis of 1-monosubstituted and 1,4-disubstituted 1H-1,2,3-triazoles was established under continuous flow conditions using copper-on-charcoal as a heterogeneous catalyst. This methodology allowed for the synthesis of a diverse set of substituted 1,2,3-triazoles with good functional group tolerance and high yields. 2-Ynoic acids were also used as small-chain alkyne donors in a decarboxylation/cycloaddition cascade, allowing gaseous reagents to be bypassed, delivering desired triazoles in high yields. The developed methodology was used to synthesize an antiepileptic agent, rufinamide, which was obtained in 96% isolated yield.

Copper-on-charcoal is an excellent heterogeneous catalyst for the alkyne–azide cycloaddition reaction performed under continuous flow conditions. 2-Ynoic acids undergo decarboxylation/cycloaddition cascade giving triazoles bearing small alkyl chains.

Design and synthesis of 3,3'-triazolyl biisoquinoline N,N'-dioxides via Hiyama cross-coupling of 4-trimethylsilyl-1,2,3-triazoles

A new strategy to effectively lock the conformation of substituents at the 3,3'-positions of axial-chiral biisoquinoline N,N'-dioxides was developed based on the strong dipole-dipole interaction between 1,2,3-triazole and pyridine N-oxide rings. The crystal structure and the DFT calculations of 3,3'-bis(1-benzyl-1H-1,2,3-triazole-4-yl)-1,1'-biisoquinoline N,N'-dioxide (3a) provided strong support for this strategy. Furthermore, we successfully demonstrated that readily available 4-trimethylsilyl-1,2,3-triazoles are viable nucleophiles for Hiyama cross-coupling.

Structural Studies on Bioactive Compounds. Part 37.1 Suzuki Coupling of Diaminopyrimidines: A New Synthesis of the Antimalarial Drug Pyrimethamine

Suzuki reactions have been used successfully to effect cross-coupling of 5-halopyrimidines with 4-chlorobenzeneboronic acid and 2,4-diamino-5-(4-chloro-3-halo)-6-ethylpyrimidines with 4-methoxybenzeneboronic acid. The antimalarial drug pyrimethamine has been prepared by coupling 2,4-diamino-6-ethyl-5-iodopyrimidine with 4-chlorobenzeneboronic acid.

Dibenzyl({1-[(4-methyl-2-phenyl-4,5-dihydro-1,3-oxazol-4-yl)methyl]-1H-1,2,3-triazol-4-yl}methyl)amine

In the title compound, C28H29N5O, the molecule adopts an approximate U-shape, a conformation imposed at least in part by an intramolecular π–π contact between the two five-membered rings, which display a centroid-to-centroid separation of 3.6522 (7) Å. The planes of these rings are inclined to one another by 66.12 (5)°. A weak intramolecular C—H...·N hydrogen bond is also found. The planes of the phenyl rings of the amine unit are inclined at a dihedral angle of 81.10 (4)°, while that of the 4,5-dihydrooxazole ring makes an angle of 11.74 (8)° with its phenyl substituent. The crystal packing is stabilized by C—H...N hydrogen bonds that form chains parallel to thebaxis. Several C—H...π(ring) contacts are also present.

Design, synthesis, and computational studies on dihydropyrimidine scaffolds as potential lipoxygenase inhibitors and cancer chemopreventive agents

Dihydropyrimidine scaffold has a wide range of potential pharmacological activities such as antiviral, antitubercular, antimalarial, anti-inflammatory, and anticancer properties. 5-Lipoxygenase enzyme is an enzyme responsible for the metabolism of arachidonic acid to leukotrienes. The elevated levels of this enzyme and its metabolites in cancer cells have a direct relation on the development of cancer when compared to normal cells. The development of novel lipoxygenase inhibitors can have a major role in cancer therapy. A series of substituted 1,4-dihydropyrimidine analogues were synthesized and characterized by (1)H-NMR, (13)C-NMR, and HRMS. Molecular docking against lipoxygenase enzyme (protein data bank code =3V99) was done using Molecular Operating Environment 2013.08 and Leadit 2.1.2 softwares and showed high affinities. The synthesized compounds were tested for their lipoxygenase inhibitory activity and showed inhibition ranging from 59.37%±0.66% to 81.19%±0.94%. The activity was explained by a molecular docking study. The title compounds were also tested for cytotoxic activity against two human cancer cell lines Michigan Cancer Foundation-7 and human melanoma cells and a normal peripheral blood mononuclear cell line.

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.

Synthesis and biological evaluation of novel 1,2,3-triazolonucleotides

A general procedure for the preparation of 1,2,3-triazole analogs of nucleosides from diethyl 2-azidoethoxymethyl- and 2-azidoethoxyethylphosphonates was elaborated. The application of microwave irradiation shortened the reaction time to 10 min in comparison to ca. 48 h when 1,3-dipolar cycloadditions were performed under standard conditions. All compounds were evaluated in vitro for inhibitory activity against a broad variety of DNA and RNA viruses. None of the compounds were antivirally active at subtoxic concentrations. Compound 17k exhibited moderate inhibitory effects on the proliferation of human T-lymphocyte cells (IC50=64 µM for CEM).

Design, synthesis, antiviral, and cytotoxic evaluation of novel phosphonylated 1,2,3-triazoles as acyclic nucleotide analogues

The 1,3-dipolar cycloaddition of diethyl 2-azidoethyl-, 3-azidopropyl-, 2-azido-1-hydroxyethyl-, 3-azido-2-hydroxypropylphosphonates with selected N-propargyl nucleobases gave a series of the phosphonylated 1,2,3-triazole acyclonucleosides in which the phosphonate residue and nucleobases were linked by three- and four-carbon chains. Under standard conditions (TMSBr, ethanol), all synthesized O,O-diethylphosphonates were transformed into the respective phosphonic acids. All compounds were evaluated in vitro for activity against a broad variety of DNA and RNA viruses. Unfortunately, no antiviral activity was observed at 100 μM.