Regioselective synthesis, characterization and antimicrobial evaluation of S-glycosides and S,N-diglycosides of 1,2-Dihydro-5-(1H-indol-2-yl)-1,2,4-triazole-3-thione

Novel hybrid thiazoles, bis-thiazoles linked to azo-sulfamethoxazole: Synthesis, docking, and antimicrobial activity

The reaction of sulfamethoxazolehydrazonoyl chloride with thiosemicarbazones, bis-thiosemicarbazones, or 4-amino-3-mercapto-1,2,4-triazole in dioxane in the presence of triethylamine as a basic catalyst at reflux resulted in the regioselective synthesis of thiazoles and bis-thiazoles linked to azo-sulfamethoxazole as novel hybrid molecules. The structures of the new compounds were confirmed using a range of spectra. Each compound's antibacterial properties were evaluated using the agar well-diffusion technique, and most of them demonstrated significant potency. In silico investigations revealed that the described compounds had strong interactions with the binding sites of MurE ligase, tyrosyl-tRNA synthetase, and dihydropteroate synthase, demonstrating inhibitory activity.

New syntheses of thiosaccharides utilizing substitution reactions

Novel synthetic methods published since 2005 affording carbohydrates containing sulfur atom(s) are reviewed. The review is divided to subchapters based on the position of sulfur atom(s) in the sugar molecule. Only those methods that take advantage of substitution are discussed.

Synthesis, X-ray Crystal Structure, Anticancer, Hirshfeld Surface Analysis, DFT, TD-DFT, ADMET, and Molecular Docking of 3-Phenyl-1,2,4-triazolo[3,4-h]-13,4-thiaza-11-crown-4

In this work, we describe the synthesis of new macrocycles derived from 3-phenyl-1,2,4-triazole-5-thione 1 in a heterogeneous medium using liquid–solid phase transfer catalysis (PTC) conditions. The structures of the two compounds (3 and 4) isolated were elucidated based on spectral data (1H-NMR, 13C-NMR) and confirmed in the case of 3-phenyl-1,2,4-triazolo [3,4-h]-13,4--thiaza-11-crown-4 (3) by a single-crystal X-ray diffraction analysis. Furthermore, the experimental spectral and the X-ray geometrical parameters were compared with their corresponding predicted ones obtained at the B3LYP/6-311++G(d,p) level of theory. The intercontacts between crystal units were investigated through Hirshfeld surface analysis. The drug-like macrocycles were predicted using ADMET and drug-likeness properties, which showed that 3 may act as an inhibitor of DNA-dependent protein kinase (DNA-PK). This assumption was confirmed by the well-binding fitting of 3 into the binding site of DNA-PK and the formation of a stable 3-DNA-PK complex with a binding energy of −7 kcal-mol−1. Finally, the anticancer activity of 3 was assessed by an MTT assay against A549 cells, which showed that 3 has moderate anticancer activity compared to that of the doxorubicin reference drug.

1,2,4-Triazoles as Important Antibacterial Agents

The global spread of drug resistance in bacteria requires new potent and safe antimicrobial agents. Compounds containing the 1,2,4-triazole ring in their structure are characterised by multidirectional biological activity. A large volume of research on triazole and their derivatives has been carried out, proving significant antibacterial activity of this heterocyclic core. This review is useful for further investigations on this scaffold to harness its optimum antibacterial potential. Moreover, rational design and development of the novel antibacterial agents incorporating 1,2,4-triazole can help in dealing with the escalating problems of microbial resistance.

Expeditious Green Synthesis of Novel 4-Methyl-1,2,5,6-tetraazafluoranthen-3(2H)-one Analogue from Ninhydrin: N/S-Alkylation and Aza-Michael Addition

A straightforward green synthesis of 4-methyl-1,2,5,6-tetraazafluoranthen-3(2H)-one 6 is reported from ninhydrin 1 via condensation with ethyl acetoacetate, followed by cyclization with hydrazine hydrate in water as a benign solvent. Tetraazafluoranthen-3-thione 7 was obtained using Lawesson's reagent. N-alkylated tetraazafluoranthen-3-one 8-12 and S-alkylated analogues 13-15 were synthesized via alkylation. The investigation of the unique reactivity of 4-methyl-1,2,5,6-tetraazafluoranthen-3(2H)-one/thione toward the alkylation and aza-Michael additions was explored.

Synthesis and Anti-Proliferative Assessment of Triazolo-Thiadiazepine and Triazolo-Thiadiazine Scaffolds

A series of triazolo-thiadiazepines 4a–k were synthesized with excellent yields using dehydrated PTSA as a catalyst in toluene. Two triazolo-thiadiazines were obtained; 8a was formed directly by reflux in ethanol, whereas, PTSA promoted the formation of 8b. The molecular structure of the formed triazolo-thiadiazepines is identical to the imine-form 4a–k and not the enamine-tautomer 6a–k. The structures of the newly synthesized triazolo-thiadiazepines 4a–k and triazolo-thiadiazines 8a–b were elucidated using NMR (¹H, and ¹³C), 2D NMR, HRMS, and X-ray single crystal. Furthermore, 4a was deduced using X-ray single crystal diffraction analysis. These new thiadiazepine hits represent an optimized series of previously synthesized indole-triazole derivatives for the inhibition of EGFR. The cytotoxicity activity against two cancer cell lines including human liver cancer (HEPG-2) and breast cancer (MCF-7) was promising, with IC₅₀ between 12.9 to 44.6 µg/mL and 14.7 to 48.7 µg/mL for the tested cancer cell lines respectively, compared to doxorubicin (IC₅₀ 4.0 µg/mL). Docking studies revealed that the thiadiazepine scaffold presented a suitable anchor, allowing good interaction of the various binding groups with the enzyme binding regions and sub-pockets.

Design and synthesis of a new series of 3,5-disubstituted isoxazoles active against Trypanosoma cruzi and Leishmania amazonensis

Chagas disease and leishmaniasis are neglected tropical diseases (NTDs) endemic in developing countries. Although there are drugs available for their treatment, efforts on finding new efficacious therapies are continuous. The natural lignans grandisin (1) and veraguensin (2) show activity against trypomastigote T. cruzi and their scaffold has been used as inspiration to design new derivatives with improved potency and chemical properties. We describe here the planning and microwave-irradiated synthesis of 26 isoxazole derivatives based on the structure of the lignans 1 and 2. In addition, the in vitro evaluation against culture trypomastigotes and intracellular amastigotes of T. cruzi and intracellular amastigotes of L. amazonensis and L. infantum is reported. Among the synthesized derivatives, compounds 17 (IC₅₀ = 5.26 μM for T. cruzi), 29 (IC₅₀ = 1.74 μM for T. cruzi) and 31 (IC₅₀ = 1.13 μM for T. cruzi and IC₅₀ = 5.08 μM for L. amazonensis) were the most active and were also evaluated against recombinant trypanothione reductase of T. cruzi in a preliminary study of their mechanism of action.

Design, selective alkylation and X-ray crystal structure determination of dihydro-indolyl-1,2,4-triazole-3-thione and its 3-benzylsulfanyl analogue as potent anticancer agents

Three sets of substituted indolyl-triazoles were synthesized by the alkylation of 1,2-dihydro-5-(1H-indol-2-yl)-1,2,4-triazole-3-thione with different alkyl halides. The use of pyridine restricted the alkylation to sulfur. Whereas, upon using K₂CO₃, the alkylation exceeded sulfur to one of the remaining triazole nitrogens. The assignment of which nitrogen is alkylated besides sulfur is made for the first time using X-ray analysis of single crystals and 2D NMR which indicated that S-, 2-N-isomers will be preferably formed over the S-, 1-N-isomers. The antiproliferative activity on HEPG-2 and MCF-7 cancer cell lines was tested. The results showed that compound 2a is the most active with an IC50 3.58 μg/mL and 4.53 μg/mL for HEPG-2 and MCF-7 respectively and compound 7 is the least active with an IC₅₀ > 100 μg/mL compared to the standard drug doxorubicin (IC₅₀ 4.0 μg/mL). The interaction of the synthesized compounds with tyrosine kinases, namely, Akt, PI3, and EGFR was also studied using molecular docking simulation to predict their mode of action which will drive future work directions.

Regioselectivity of the alkylation of S-substituted 1,2,4-triazoles with dihaloalkanes

Background

1,2,4-Triazole3-thiones are good scaffolds for preparation of new lead compounds. Their derivatives attracted the attention of chemists due to their wide spectrum of biological activities. Alkylsulfanyl-1,2,4-triazoles have three nucleophilic sites (nitrogens) ready for reaction with electrophiles. Herein, new regioselective isomers were synthesized by the reaction of benzylsulfanyl-1,2,4-triazole with various dihaloalkanes. Regioselectivity was determined by X-ray crystallography and NMR.

Results

Coupling of 3-benzylsufanyl-5-(1H-indolyl)-1,2,4-triazole with dibromomethane, 1,2-dichloroethane, 1,3-dibromopropane and di(bromomethyl)quinoxaline was investigated in the presence of potassium carbonate in acetone. In the case of dibromomethane three different bis(triazolyl)methane isomers (–N¹–CH₂–N¹-4, –N¹–CH₂–N²-5, –N²–CH₂–N²-6) were formed in which the two bromide atoms were replaced by two triazole moieties. Among these isomers the reaction was regioselective towards the –N¹–CH₂–N²-5 isomer due to the steric effect. In the case of 1,3-dibromopropane two compounds were obtained due to the alkylation at N(2) to give 2-(3-bromopropyl)-triazole 8 and alkylation at N(1) was followed by cyclization at the indole nitrogen to form a condensed indolo-triazolo-diazepine 10. Upon alkylation of 3-benzylsufanyl-5-(1H-indolyl)-1,2,4-triazole with di(bromomethyl)quinoxaline, two bis(triazolyl-methyl)quinoxaline isomers were separated and characterized as (–N¹–CH₂–N¹–) 11 and (–N²–CH₂–N²–) 12. Single-crystal X-ray diffraction assisted the elucidation and confirmation of the structures of the isomers. An AM1 theoretical study explained the regioselectivity of the alkylation.

Conclusions

On reacting S-protected 1,2,4-triazoles with various alkylating agents, only N(1) and N(2) attack the electrophilic carbons. N(2) alkylated isomers are preferentially formed.

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-016-0165-0) contains supplementary material, which is available to authorized users.

Synthesis of New Functionalized Indoles Based on Ethyl Indol-2-carboxylate

Successful alkylations of the nitrogen of ethyl indol-2-carboxylate were carried out using aq. KOH in acetone. The respective N-alkylated acids could be obtained without separating the N-alkylated esters by increasing the amount of KOH and water. The use of NaOMe in methanol led to transesterification instead of the alkylation, while the use of NaOEt led to low yields of the N-alkylated acids. Hydrazinolysis of the ester gave indol-2-carbohydrazide which then was allowed to react with different aromatic aldehydes and ketones in ethanol catalyzed by acetic acid. Indol-2-thiosemicarbazide was used in a heterocyclization reaction to form thiazoles. The new structures were confirmed using NMR, mass spectrometry and X-ray single crystal analysis.

Hybrids of coumarin–indole: design, synthesis and biological evaluation in Triton WR-1339 and high-fat diet induced hyperlipidemic rat models

Lipid lowering activity of novel coumarin–indole hybrids has been demonstrated.

Recent advances bioactive 1,2,4-triazole-3-thiones

Triazoles are heterocyclic compounds which have a five-membered ring of two carbon atoms and three nitrogen atoms. These structures have been interest in the development of novel compounds with anticonvulsant, antidepressant, antioxidant, anti-inflammatory, analgesic, antinociceptive, antibacterial, antimycobacterial, antifungal, antiviral, anticancer, anti-parasitic, anti-urease and other activities. Therefore, many researchers have synthesized these compounds as target structures and evaluated their biological activities. This review contains various pharmacological activities of 1,2,4-triazole-3-thiones in one place and it is also the milestone for the new research towards this moiety.