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C-glycopyranosyl derivatives of six-membered heterocycles are scarcely represented in the chemical literature and the title 3-glycopyranosyl-1,2,4-triazines are completely unknown. In this paper, the first synthesis of this compound class is accomplished by the cyclocondensation of C-glycosyl formamidrazones and 1,2-dicarbonyl derivatives. In addition, the synthesis of C-glycopyranosyl 1,2,4-triazin-5(4H)-ones was also carried out by the transformation of the above formamidrazones with α-keto-carboxylic esters. Inverse electron demand Diels–Alder reactions of 3-glycopyranosyl-1,2,4-triazines with a bicyclononyne derivative yielded the corresponding annulated 2-glycopyranosyl pyridines.

A total of 21 novel xanthone and acridone derivatives were synthesized using the reactions of 1,2,4-triazine derivatives with 1-hydroxy-3-methoxy-10-methylacridone, 1,3-dimethoxy-, and 1,3-dihydroxanthone, followed by optional dihydrotiazine ring aromatization. The synthesized compounds were evaluated for their anticancer activity against colorectal cancer HCT116, glioblastoma A-172, breast cancer Hs578T, and human embryonic kidney HEK-293 tumor cell lines. Five compounds (7a, 7e, 9e, 14a, and 14b) displayed good in vitro antiproliferative activities against these cancer cell lines. Compounds 7a and 7e demonstrated low toxicity for normal human embryonic kidney (HEK-293) cells, which determines the possibility of further development of these compounds as anticancer agents. Annexin V assay demonstrated that compound 7e activates apoptotic mechanisms and inhibits proliferation in glioblastoma cells.

The close similarity in patterns of bands in the microwave spectra of the isomeric 1,2,3- and 1,2,4-triazines has enabled assignment for the 1,2,3-isomer. Pure rotational transitions with J up to 65 were identified and fitted to a Watson-type Hamiltonian: A = 6334.157(14)., B = 6271.289(14), C = 3151.230(14). A and B thus show near degeneracy. Coupled cluster calculations which include both singles, doubles and selected triple excitations (CCSD(T)), give very close agreement with the spectral data. The theoretical structure which includes estimates of the 14N quadrupole coupling, not determined in the spectrum, is described. Postprint

This review focuses on the cytotoxic effect of new synthetic pyrazolo[4,3-e][1,2,4]triazine derivatives against different tumor cell lines. Some annulated pyrazolotriazines i.e., pyrazolo[4,3-e][1,2,4]triazolo[4,3-b][1,2,4]triazines and pyrazolo[4,3-e]tetrazolo[1,5-b][1,2,4]triazine demonstrated significant broad cytotoxic activity in micromolar range concentration, which could have excellent potential to be new candidate therapeutic agents in cancer chemotherapy.

A series of 34 new pyrimido[2,1-c][1,2,4]triazine-3,4-diones were synthesized and fully characterized using IR, NMR, MS, and microanalytical analysis. In vitro investigation of 12 compounds of this series revealed promising antimicrobial activity of the conjugates 15a and 15f–j that were tagged with electron-withdrawing groups, with sensitivities ranging from 77% to as high as 100% of the positive control. The investigation of antimicrobial activity included Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6535, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 8739 (EC), and fungal strains Candida albicans ATCC 10231 and Aspergillus brasiliensis ATCC 16404.

In this work, a series of novel 1,2,4-triazine-chalcone hybrids were designed through the molecular hybridization strategy, synthesized by two step chlorinations and further aldol condensation and evaluated their antiproliferative activity against MGC-803, HCT-116, PC-3, EC-109 and A549 cells. Compound 9l displayed significant antiproliferative activity against MGC-803, HCT-116, PC-3, EC-109 and A549 cell lines with IC50 values of 0.41, 0.43, 0.61, 0.78 and 0.52 μM, respectively. Subsequent mechanistic investigations suggested that compound 9l induced the generation of ROS and inhibited the activation of the ERK pathway. Compound 9l induced extrinsic cell apoptosis by up-regulating DR5 dependent on the generation of ROS, while up-regulation of DR5 caused by compound 9l relied on the inhibition of ERK. Thus, compound 9l inhibited the gastric cancer cells via an axis of ROS-ERK-DR5 in vitro. Compound 9l also showed potent activity on cell proliferation inhibition, and was effective in suppressing the growth of MGC-803 xenograft tumor in nude mice without obvious toxicity. Therefore, compound 9l is to be reported as anti-gastric cancer agent in vitro and in vivo via an axis of ROS-ERK-DR5.

A series of 34 new pyrimido[2,1-c][1,2,4]triazine-3,4-diones were synthesized and fully characterized using IR, NMR, MS, and microanalytical analysis. In vitro investigation of 12 compounds of this series revealed promising antimicrobial activity of the conjugates 15a and 15f&ndash, j that were tagged with electron-withdrawing groups, with sensitivities ranging from 77% to as high as 100% of the positive control. The investigation of antimicrobial activity included Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6535, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 8739 (EC), and fungal strains Candida albicans ATCC 10231 and Aspergillus brasiliensis ATCC 16404.

4-Benzyl-1,2,4-triazin-3,5(2H,4H)-dione (3-benzyl-6-azauracil, 2), and 2,4-dibenzyl-1,2,4-triazin-3,5(2H,4H)-dione (1,3-dibenzyl-6-azauracil, 3) were synthesized by the reaction of 1,2,4-triazin-3,5(2H,4H)-dione (6-azauracil, 1) with benzyl bromide and potassium carbonate in dry acetone via the 18-crown-6-ether catalysis. In these reaction methods, we developed more convenient and efficient methodologies to afford compounds 2 and 3 in good yields. These compounds were characterized by 1H- and 13C-NMR, MS spectrum, IR spectroscopy and elemental analysis. The structure of 2 was verified by 2D-NMR measurements, including gHSQC and gHMBC measurements. A single-crystal X-ray diffraction experiment indicated that compound 3, with the molecular formula C17H15N3O2, crystallized from a CH3OH/CH2Cl2 diffusion solvent system in a monoclinic space group P21/c with a = 13.7844(13), b = 8.5691(8), c = 13.0527(12) Å, β = 105.961(2)°, V = 1482.3(2) Å3, Z = 4, resulting in a density Dcalc of 1.314 g/cm3. The crystal structure of compound 3 is tightly stabilized by contact with five other molecules from the six short contacts formed by intermolecular C−O···H−Car, C−H···Car, and weakly π···π stacking interactions. The dihedral angle 31.90° is formed by the mean planes of the benzene rings of the N-2 and N-4 benzyl groups.

On interacting α-bromoacetophenones with aromatic carboxylic acid hydrazides, the formation of two reaction products was observed in certain cases, the expected 1,2,4-triazine and the phenylglyoxal dihydrazone as an unexpected product. The effect of substituents in the initial substrates and of the conditions of carrying out the synthesis on the direction of the reaction have been studied. © 2013 Springer Science+Business Media New York.

The 'triazine' methodology for the synthesis of functionalized pyridine ligands proved to be a convenient method for the preparation of a luminescent Pt(II) complex. The key ligand can be assembled easily starting from readily accessible reagents. Further cycloplatination and post-functionalization led to the ready-to-go luminescent 'tag' 2 for peptide labeling. © 2012 Elsevier Ltd. All rights reserved.

A series of new 7-substitued-4H-1,3,4-thiadiazolo[2,3-c][1,2,4]- triazin-4-oneswere synthesized in good yields by the reaction of 4-amino-3- mercapto-1,2,4-triazin-5(4H)-one with various aromatic carboxylic acids in the presence of phosphorus oxychloride. All the synthesized compounds were confirmed by FT-IR, NMR (1H and 13C), ESI-MS spectroscopic techniques and analytical methods.

The selectively 15N labeled azido-1,2,4-triazine 2*A and azidopyrimidine 4*A were synthesized by treating hydrazinoazines with 15N-labeled nitrous acid. The synthesized compounds were studied by 1H, 13C, and 15N NMR spectroscopy in DMSO, TFA, and DMSO/TFA solutions, where the azide-tetrazole equilibrium could lead to the formation of two tetrazoles (T, T′) and one azide (A) isomer for each compound. The incorporation of the 15N label led to the appearance of long-range 1H-15N coupling constants (JHN), which can be measured easily by using amplitude-modulated 1D 1H spin-echo experiments with selective inversion of the 15N nuclei. The observed JHN patterns enable the unambiguous determination of the mode of fusion between the azole and azine rings in the two groups of tetrazole isomers (2*T′, 4*T′ and 2*T, 4*T), even for minor isoforms with a low concentration in solution. However, the azide isomers (2*A and 4*A) are characterized by the absence of detectable J HN coupling. The analysis of the JHN couplings in 15N-labeled compounds provides a simple and efficient method for direct NMR studies of the azide-tetrazole equilibrium in solution. © 2013 American Chemical Society.

Intramolecular inverse electron demand cycloadditions of isatin-derived 1,2,4-triazines with acetylenic dienophiles tethered by amidations or transesterifications proceed in excellent yields to produce lactam- or lactone-fused α-carbolines. Beginning with various isatins and alkynyl dienophiles, a pilot-scale library of eighty-eight α-carbolines was prepared by using this robust methodology for biological evaluation.