Synthesis of new pyrazolo[5,1-c][1,2,4] benzotriazines, pyrazolo[5,1-c]pyrido[4,3-e][1,2,4] triazines and their open analogues as cytotoxic agents in normoxic and hypoxic conditions

A new crystal form and anti-microbial activity of (E)-1-[3-(2-hy-droxy-benzyl-idene-amino)-phen-yl]ethanone

The title Schiff base compound, C15H13NO2, crystallizes in a new crystal form in the space group P212121, which is different from the monoclinic P21/n space group reported previously [De et al. (2009 ▸). Indian J. Chem. Sect. B, 48, 595-598]. An intra-molecular O-H⋯N hydrogen bond occurs between the hy-droxy and azomethine moieties. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds into supra-molecular chains propagating along the b-axis direction with a C(8) graph-set motif. The contribution of these two contacts in Hirshfeld surface area are around 19 and 21%, respectively. The title compound was screened for its anti-bacterial activity against two gram-negative (Escherichia coli and Salmonella typhimurium) and one gram-positive (Staphyloccus aureus) bacteria. The results of this study reveal that this Schiff base shows good activity against only one bacterium, i.e. Salmonella typhimurium.

Synthesis and Pharmacological Studies of Unprecedented Fused Pyridazino[3',4':5,6][1,2,4]triazino[3,4-b][1,3,4]thiadiazine Derivatives

A novel fused system with three or four fused rings—pyridazino[3′,4′:5,6][1,2,4]triazino[4,3-b][1,2,4,5]tetrazine and pyridazino[3′,4′:5,6][1,2,4]triazino[3,4-b]pyrimido[4,5-e][1,3,4]thiadiazine was obtained from the starting materials 4(6H)-amino-3-hydrazino-7-(2-thienyl)pyridazino[3,4-e][1,2,4]-triazine 2 and 9-amino-3-(2-thienyl)-2H,8H-pyridazino[3′,4′:5,6][1,2,4]triazino[3,4-b][1,3,4]thiadiazine-8-carbonitrile 12. Each of the starting compounds was subjected to a number of cyclization reactions to obtain a series of new heterocyclic fused systems, 3⁻10 and 13⁻23, via bifunctional reagents. Some of the synthesized compounds were screened against three cell lines including HepG2, HCT-116 and MCF-7 to discover their anticancer activity. The synthesized compounds were characterized depending on their elemental analyses and spectral data.

An overview on the recent developments of 1,2,4-triazine derivatives as anticancer compounds

The synthesis, the antitumor activity, the SAR and, whenever described, the possible mode of action of 1,2,4-triazine derivatives, their N-oxides, N,N'-dioxides as well as the benzo- and hetero-fused systems are reported. Herein are treated derivatives disclosed to literature from the beginning of this century up to 2016. Among the three possible triazine isomers, 1,2,4-triazines are the most studied ones and many derivatives having remarkable antitumor activity have been reported in the literature and also patented reaching advanced phases of clinical trials.

Synthesis of some new pyrazolo[1,5-a]pyrimidine, pyrazolo[5,1-c]triazine, 1,3,4-thiadiazole and pyridine derivatives containing 1,2,3-triazole moiety

Background

Pyrazolo[1,5-a]pyrimidines are purine analogues. They have beneficial properties as antimetabolites in purine biochemical reactions. This division compounds have attracted wide pharmaceutical interest because of their antitrypanosomal activity.

Results

The present work depicts an effective synthesis convention of pyrazolo[1,5-a]pyrimidines, pyrazolo[5,1-c]triazines, thieno[2,3-b]pyridines and polysubstituted pyridines containing 1,2,3,-triazole moiety from the reaction of sodium 3-(5-methyl-1-(p-toly)-1H-1,2,3-triazol-4-yl)-3-oxoprop-1-en-1-olate with the fitting heterocyclic amines and its diazonium salt, and active methylene compounds, individually. Likewise, thiazoles and, 1,3,4-thiadiazoles were obtained from 2-bromo-1-(5-methyl-1-(p-tolyl)-1H-1,2,3-triazol-4-yl)ethanone and some reagent such as hydrazonoyl chlorides and halo ketones. The newly synthesized compounds were established by elemental analysis, spectral data, and alternative synthetic route whenever possible.

Conclusions

New series of pyrazolo[1,5-a]pyrimidines, pyrazolo[5,1-c]triazines, thieno[2,3-b]pyridines and polysubstituted pyridines containing the 1,2,3,-triazole moiety were synthesized via reactions of sodium 3-(5-methyl-1-(p-toly)-1H-1,2,3-triazol-4-yl)-3-oxoprop-1-en-1-olate with the appropriate heterocyclic amines and its diazonium salt. In addition, 1,3,4-thiadiazoles and, 1,3-thiazoles were acquired in a decent yield via the reaction of substituted thiourea with the appropriate hydrazonoyl chlorides and halogenated ketenes.Graphical abstract

Synthesis and structure elucidation of novel fused 1,2,4-triazine derivatives as potent inhibitors targeting CYP1A1 activity

Synthesis and structure elucidation of new series of novel fused 1,2,4-triazine derivatives 3a-3f, 4a-4i and 6a-6b and their inhibitory activities are presented. Molecular structures of the synthesized compounds were confirmed by (1)H NMR, (13)C NMR, MS spectra and elemental analyses. X-ray crystallographic analysis was performed on 2-acetyl-8-(N,N-diacetylamino)-6-(4-methoxybenzyl)-3-(4-methoxy-phenyl)-7-oxo-2,3-dihydro-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazine 3d and 2-acetyl-8-(N-acetylamino)-6-benzyl-3-(4-chlorophenyl)-3-methyl-7-oxo-2,3-dihydro-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazine 4e to secure their structures. The inhibitory effect of these compounds toward the CPY1A1 activity was screened to determine their potential as promising anticancer drugs. Our data showed that compounds 4e, 5a, 5b and 6b possess the highest inhibitory effects among all tested compounds. Furthermore, analysis of triazolotriazine derivatives docking showed that these compounds bind only at the interface of substrate recognition site 2 (SRS2) and (SRS6) at the outer surface of the protein. Amino-acids ASN214, SER216 and ILE462 participate in the binding of these compounds through H-bonds.

3,4-Dimethyl-2-(2-oxo-2-phenylethyl)-2H,4H-pyrazolo[4,3-c][1,2]benzothiazine-5,5-dione

In the title mol­ecule, C₁₉H₁₇N₃O₃S, the heterocyclic thia­zine ring adopts a half-chair conformation with the S and N atoms displaced by 0.530 (5) and 0.229 (6) Å, respectively, on opposite sides of the mean plane formed by the remaining ring atoms. The ethanone group lies at an angle of 3.8 (3)° with respect to the benzene ring, which lies almost perendicular to the pyrazole ring, with a dihedral between the two planes of 89.22 (11)°. Weak inter­molecular C—H⋯O hydrogen-bonding inter­actions are present.

2-(3,4-Dimethyl-5,5-dioxo-2H,4H-pyrazolo[4,3-c][1,2]benzothiazin-2-yl)-1-(4-methoxyphenyl)ethanone

In the title mol­ecule, C₂₀H₁₉N₃O₄S, the heterocyclic thia­zine ring adopts a half-chair conformation with the S and N atoms displaced by 0.492 (6) and 0.199 (6) Å, respectively, on opposite sides from the mean plane formed by the remaining ring atoms. The ethanone group lies at an angle of 9.4 (2)° with respect to the benzene ring, which lies almost perpendicular to the pyrazole ring, with a dihedral between the two planes of 78.07 (9)°. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds.

Synthesis and anti-bacterial activities of some novel Schiff bases derived from aminophenazone

A series of 1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one-containing Schiff bases were synthesized, characterized and screened for their antibacterial activities. The structures of the synthesized compounds were established by spectroscopic (FT-IR, ¹H-NMR, ¹³C-NMR, MS) and elemental analyses. The anti-bacterial activities (with MIC values) of compounds were evaluated. The anti-bacterial screening results reveal that among the six compounds screened, four compounds showed moderate to good anti-bacterial activity. Among the tested compounds, the most effective compounds against four bacterial strains, viz. Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Streptococcus pyogenes, are [(2-Chlorobenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one (4) and [(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylimino)methyl]benzonitrile(5) with MIC values of 6.25 μg/mL.