Benzotriazole: An overview on its versatile biological behavior

Benzotriazoles and bisphenols in wastewater from the food processing industry and the quantitative changes during mechanical/biochemical treatment processes

Benzotriazoles (BTRs) and bisphenols (BPs), categorized as contaminants of emerging concern (CECs), pose significant risks to human health and ecosystems due to their endocrine-disrupting properties and environmental persistence. This study investigates the occurrence and behavior of nine BTRs and ten BPs in wastewater generated in a large-scale meat processing plant, evaluating the effectiveness of a modern mechanical-biological industrial on-site treatment plant in removing these contaminants, and based on the concentration levels from eleven sampling points at different stages of the treatment process. The method used to determine these micropollutants' concentration was ultrasound-assisted emulsification-microextraction for analytes isolation and gas chromatography-mass spectrometry for detection (USAEME-GC/MS). The results indicate that the rigorous quality control processes in the meat processing facility effectively limit the presence of these micropollutants, especially concerning BPs, which are absent or below detection limits in raw wastewater. While the concentrations of some of these micropollutants increased at different points in the treatment process, these values were relatively low, typically below one microgram per liter. Among the compounds analyzed, the only one present after completing the treatment was 5Cl-BTR (maximum concentration: 3007 ng/L), and these contamination levels are around seven times lower than the reference value associated with non-cancer health risk for drinking water. This study contributes to understanding these CECs in industrial wastewater and highlights the importance of effective treatment systems for environmental protection.

Recent synthetic strategies for the functionalization of fused bicyclic heteroaromatics using organo-Li, -Mg and -Zn reagents

This review highlights the use of functionalized organo-Li, -Mg and -Zn reagents for the construction and selective functionalization of 5- and 6-membered fused bicyclic heteroaromatics. Special attention is given to the discussion of advanced syntheses for the preparation of highly functionalized heteroaromatic scaffolds, including quinolines, naphthyridines, indoles, benzofurans, benzothiophenes, benzoxazoles, benzothiazoles, benzopyrimidines, anthranils, thienothiophenes, purine coumarins, chromones, quinolones and phthalazines and their fused heterocyclic derivatives. The organometallic reagents used for the desired functionalizations of these scaffolds are generally prepared in situ using the following methods: (i) through directed selective metalation reactions (DoM), (ii) by means of halogen/metal exchange reactions, (iii) through oxidative metal insertions (Li, Mg, Zn), and (iv) by transmetalation reactions (organo-Li and Mg transmetalations with ZnCl2 or ZnO(Piv)2). The resulting reactive organometallic reagents allow a wide range of C-C, C-N and C-X cross-coupling reactions with different electrophiles, employing in particular Kumada or Negishi protocols among other transition metal (Pd, Ni, Co, Cu, Cr, Fe, etc.)-catalyzed processes. In addition, key developments concerning selective metalation techniques will be presented, which rely on the use of RLi, LDA and TMP metal bases. These methods are now widely employed in organic synthetic chemistry and have proven to be particularly valuable for drug development programs in the pharmaceutical industry. New and improved protocols have resulted in many Li, Mg and Zn organyls now being compatible with functionalized aryl, heteroaryl, alkenyl, alkynyl and alkyl compounds even in the presence of labile functional groups, making these reagents well-suited for C(sp2)-C(sp2), C(sp2)-C(sp) and C(sp2)-C(sp3) cross-coupling reactions with fused heteroaryl halides. In addition, the use of some transition metal-catalyzed processes occasionally allows a reversed role of the reactants in cross-coupling reactions, providing alternative synthetic routes for the preparation of fused heteroaromatic-based bioactive drugs and natural products. In line with this, this article points to novel methods for the functionalization of bicyclic heteroaromatic scaffolds by organometallic reagents that have been published in the period 2010-2023.

Harnessing benzotriazole as a sustainable ligand in metal-catalyzed coupling reactions

Coupling reactions play a crucial role in drug development enabling the rapid expansion of structure-activity relationships (SARs) during drug discovery programs to identify a clinical candidate and simplify subsequent drug development processes. In particular, their relevance in clinical medicine and drug discovery has increased significantly in the last two decades. To facilitate these metal-catalyzed coupling reactions, suitably designed ligands are necessary and from the industrial point of view, sustainable and cost-effective ligands are of current need. Benzotriazole, a non-toxic, thermally stable, and inexpensive bidentate ligand, exhibits strong electron donating and electron accepting properties, along with excellent solubility in various organic solvents. It has been extensively explored as a synthetic auxiliary in the past; in recent years, benzotriazole and its derivatives have been used as ligands in metal-catalyzed coupling reactions. The facile construction of carbon-carbon and carbon-heteroatom bonds in the presence of versatile benzotriazole ligands makes it an indispensable ligand for catalytic transformations. The present feature article mainly emphasizes the advances in the utilization of benzotriazole as a ligand in a diverse range of C-C, C-N, C-O, and C-S coupling reactions.

Precipitation contributes to alleviating pollution of rubber-derived chemicals in receiving watersheds: Combining confluent stormwater runoff from different functional areas

The release of rubber-derived chemicals (RDCs) in road surface runoff has received significant attention. Urban surface runoff is often the confluence of stormwater runoff from specific areas. However, the impact of precipitation on RDCs contamination in confluent stormwater runoff and receiving watersheds remains poorly understood. Herein, we investigated the profiles of RDCs and their transformation products in confluent stormwater runoff and receiving rivers affected by precipitation events. The results showed that 34 RDCs are ubiquitously present in confluent stormwater runoff and surface water, with mean concentrations of 1.03-2749 and 0.28-436 ng/L, respectively. The most dominant target compounds in each category were N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), 6PPD-quinone, 2-benzothiazolol, and 1,3-diphenylguanidine. Total RDCs concentrations in confluent stormwater runoff decreased spatially from industrial areas to business districts to college towns. A significant decrease in RDCs levels in surface water after rainfall was observed (P < 0.01), indicating that precipitation contributes to alleviating RDCs pollution in receiving watersheds. To our knowledge, this is the first report of N,N'-ditolyl-p-phenylenediamine quinone (DTPD-Q) levels in surface waters in China. The annual mass load of ∑RDCs reached 72,818 kg/y in confluent stormwater runoff, while 38,799 kg/y in surface water. The monitoring of confluent stormwater runoff is an efficient measure for predicting contamination loads from RDCs in rivers. Risk assessment suggested that most RDCs posed at least medium risks to aquatic organisms, especially 6PPD-quinone. The findings help to understand the environmental fate and risks of RDCs in the confluent stormwater runoff and receiving environments after precipitation events.

Monitoring studies on contamination of urban runoff with hazardous benzotriazoles and bisphenols in one of the least polluted places worldwide

Benzotriazoles (BTR) and bisphenols (BP) are artificial contaminants of emerging concern (CECs) commonly found in everyday products. This study focuses on urban runoff to investigate the occurrence of BTRs and BPs in Iceland, regarded as one of the least polluted places in the world, which made it reasonable to confirm or deny the presence of these micropollutants in its environment. Samples collected in February 2023 (SC1) and August 2024 (SC2) from seven locations along Iceland's Ring Road were evaluated to determine the occurrence of seven BTRs (1H-BTR, 4Me-BTR, 5Me-BTR, 5Cl-BTR, UV-P, UV-326, UV-329) and six BPs (BPF, BPE, BPA, BPZ, BPAP, BPM) in the runoff, using the ultrasound-assisted emulsification-microextraction for analytes isolation and gas chromatography-mass spectrometry for detection (USAEME-GC/MS). All locations showed detectable and varying levels of BTRs and BPs, with 5Cl-BTR (11.6 μg/L) and BPF (56.3 μg/L), both in SC1, demonstrating the highest concentrations, providing valuable insights into their prevalence and distribution. A correlational analysis investigated the connection between these pollutants and various characteristics associated with the locations along the Ring Road. This study contributes to the essential comprehension of these CECs, serving as input for future strategies for monitoring and mitigating their impact.

Recent Applications of Sulfonium Salts in Synthesis and Catalysis

The use of sulfonium salts in organic synthesis has experienced a dramatic increase during the last years that can arguably be attributed to three main factors; the development of more direct and efficient synthetic methods that make easily available sulfonium reagents of a wide structural variety, their intrinsic thermal stability, which facilitates their structural modification, handling and purification even on large scale, and the recognition that their reactivity resembles that of hypervalent iodine compounds and therefore, they can be used as replacement of such reagents for most of their uses. This renewed interest has led to the improvement of already existing reactions, as well as to the discovery of unprecedented transformations; in particular, by the implementation of photocatalytic protocols. This review aims to summarize the most recent advancements on the area focusing on the work published during and after 2020. The scope of the methods developed will be highlighted and their limitations critically evaluated.

Insights into the effect of benzotriazoles in liver using integrated metabolomic and transcriptomic analysis

Benzotriazoles (BTRs) are a class of benzoheterocyclic chemicals that are frequently used as metal-corrosive inhibitors, both in industry and daily use. However, the exposure effect information on BTRs remains relatively limited. In this study, an integrated metabolomic and transcriptomic approach was utilized to evaluate the effect of three BTRs, benzotriazole, 6-chloro-1-hydroxi-benzotriazole, and 1-hydroxy-benzotriazole, in the mouse liver with results showing disrupted basal metabolic processes and vitamin and cofactor metabolism after 28 days. The expression of several genes that are related to the inflammatory response and aryl hydrocarbon receptor pathways, such as Gstt2 and Arntl, was altered by the exposure to BTRs. Exposure to BTRs also affected metabolites and genes that are involved in the immune system and xenobiotic responses. The altered expression of several cytochrome P450 family genes reveal a potential detoxification mechanism in the mouse liver. Taken together, our findings provide new insights into the multilayer response of the mouse liver to BTRs exposure as well as a resource for further exploration of the molecular mechanisms by which the response occurs.

Theoretical exploration of the stabilities and detonation parameters of nitro-substituted 1H-benzotriazole

CONTEXT

The nitro group was introduced into the nitrogen heterocycle of 1H-benzotriazole to design a total of 31 derivatives. To estimate the thermal stability of these derivatives, the heat of formation (HOF) is calculated based on the isodesmic reaction. The bond dissociation energy (BDE) was also predicted based on the homolytic reaction to further evaluate the dynamic stability. To evaluate the possibility of utilizing as high energy density compounds (HEDCs), the detonation parameters including the detonation pressure (P), detonation velocity (D), and explosive heat (Q) are predicted by taking advantage of the Kamlet-Jacobs empirical equation. To measure the sensitivity to impact, both the characteristic height (H50) and free space in crystal (∆V) are considered in this paper. Based on our calculations, D-series and E are found to be the candidates for HEDCs.

METHODS

The Gaussian 09 software package was used in this paper. The B3PW91 hybrid function with the 6-311 + G(d,p) basis set was chosen to perform the structural optimization, frequency analysis, heat of formation, and bond dissociation energy. The detonation parameters were calculated following the Kamlet-Jacobs equation.

Novel Benzotriazole-β-lactam Derivatives as Antimalarial Agents: Design, Synthesis, Biological Evaluation and Molecular Docking Studies

Many people around the world suffer from malaria, especially in tropical or subtropical regions. While malaria medications have shown success in treating malaria, there is still a problem with resistance to these drugs. Herein, we designed and synthesized some structurally novel benzotriazole-β-lactams using 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid as a key intermediate. To synthesize the target molecules, the ketene-imine cycloaddition reaction was employed. First, The reaction of 1H-benzo[d][1,2,3]triazole with 2-bromoacetic acid in aqueous sodium hydroxide yielded 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid. Then, the treatment of 2-(1H-benzo[d][1,2,3]triazol-1-yl)acetic acid with tosyl chloride, triethyl amine, and Schiff base provided new β-lactams in good to moderate yields.The formation of all cycloadducts was confirmed by elemental analysis, FT-IR, NMR and mass spectral data. Moreover, X-ray crystallography was used to determine the relative stereochemistry of 4a compound. The in vitro antimalarial activity test was conducted for each compound against P. falciparum K1. The IC50 values ranged from 5.56 to 25.65 μM. A cytotoxicity profile of the compounds at 200 μM final concentration revealed suitable selectivity of the compounds for malaria treatment. Furthermore, the docking study was carried out for each compound into the P. falciparum dihydrofolate reductase enzyme (PfDHFR) binding site to analyze their possible binding orientation in the active site.

Molybdenum-catalyzed deoxygenative heterocyclization of 2-nitroazobenzenes: a novel strategy for catalytic synthesis of 2-aryl-2H-benzo[d][1,2,3]triazoles

A novel strategy for the catalytic synthesis of 2-aryl-2H-benzo[d][1,2,3]triazoles bearing a wide range of functional groups in good to excellent yields by non-noble molybdenum-catalyzed deoxygenative heterocyclization of 2-nitroazobenzenes is described. The salient features of the transformation include the use of readily available substrates, valuable products and ease of scale-up. The mechanistic study indicates that the reaction occurred via double deoxygenation by the Mo(VI)/Mo(IV) catalytic cycle from 2-nitroazobenzene, through the formation of 2-aryl-2H-benzo[d][1,2,3]triazole-N1-oxide or nitrene intermediates.

Phytochemistry Profile, Antimicrobial and Antitumor Potential of the Methanolic Extract of Tabernaemontana catharinensis A DC and Eragrostis plana NEES

Natural compounds that have the potential to act as antimicrobials and antitumors are a constant search in the field of pharmacotherapy. Eragrostis plana NEES (Poaceae) is a grass with high allelopathic potential. Allelopathy is associated with compounds generated in the primary and secondary metabolism of the plant, which act to protect it from phytopathogens. Tabernaemontana catharinensis A DC (Apocynaceae), a tree in which its leaves and bark are used for the preparation of extracts and infusions that have anti-inflammatory and antinociceptive effects, is attributed to its phytochemical constitution. The objective of this study was to elucidate the phytochemical constitution, the antibacterial potential, the toxicity against immune system cells, hemolytic potential, and antitumor effect of methanolic extracts of E. plana and T. catharinensis. The phytochemical investigation was carried out using the UHPLC-QTOF MS equipment. The antibacterial activity was tested using the broth microdilution plate assay, against Gram-negative and Gram-positive strains, and cytotoxicity assays were performed on human peripheral blood mononuclear cells (PBMC) and in vitro hemolysis. Antitumor activity was performed against the colon cancer cell line (CT26). Results were expressed as mean and standard deviation and analyzed by ANOVA. p < 0.05 was considered significant. More than 19 possible phytochemical constituents were identified for each plant, with emphasis on phenolic compounds (acids: vanillic, caffeic, and quinic) and alkaloids (alstovenine, rhyncophylline, amezepine, voacangine, and coronaridine). Both extracts showed antibacterial activity at concentrations below 500 µg/mL and were able to decrease the viability of CT26 at concentrations below 2000 µg/mL, without showing cytotoxic effect on PBMCs and in vitro hemolysis at the highest concentration tested. This is the first report of the activity of E. plana and T. catharinensis extracts against colon cancer cell line (CT26). Studies should be carried out to verify possible molecular targets involved in the antitumor effect in vivo.

On-DNA hydroalkylation of N-vinyl heterocycles via photoinduced EDA-complex activation

The emergence of DNA-encoded library (DEL) technology has provided a considerable advantage to the pharmaceutical industry in the pursuit of discovering novel therapeutic candidates for their drug development initiatives. This combinatorial technique not only offers a more economical, spatially efficient, and time-saving alternative to the existing ligand discovery methods, but also enables the exploration of additional chemical space by utilizing novel DNA-compatible synthetic transformations to leverage multifunctional building blocks from readily available substructures. In this report, a decarboxylative-based hydroalkylation of DNA-conjugated N-vinyl heterocycles enabled by single-electron transfer (SET) and subsequent hydrogen atom transfer through electron-donor/electron-acceptor (EDA) complex activation is detailed. The simplicity and robustness of this method permits inclusion of a broad array of alkyl radical precursors and DNA-tethered nitrogenous heterocyles to generate medicinally relevant substituted heterocycles with pendant functional groups. Moreover, a successful telescoped route provides the opportunity to access a broad range of intricate structural scaffolds by employing basic carboxylic acid feedstocks.

Synthesis, biological evaluation and in silico investigations of benzotriazole derivatives as potential inhibitors of NIMA related kinase

In the current study, a novel compound, bis(3-(2H-benzo[d][1,2,3]triazol-2-yl)-2-(prop-2-yn-1-yloxy)-5-(2,4,4-trimethylpentan-2-yl)phenyl)methane (TAJ1), has been synthesized by the reaction of 6,6'-methylenebis(2-(2H-benzo[d][1,2,3]triazol-2-yl)-4-(2,4,4-trimethylpentan-2-yl)phenol) (1), propargyl bromide (2) and potassium carbonate. Spectroscopic (FTIR, 1H-NMR, 13C-NMR) and single-crystal assays proved the structure of the synthesized sample. XRD analysis confirmed the structure of the synthesized compound, showing that it possesses two aromatic parts linked via a -CH2 carbon with a bond angle of 108.40°. The cell line activity reported a percent growth reduction for different cell types (HeLa cells, MCF-7 cells, and Vero cells) under various treatment conditions (TAJ1, cisplatin, and doxorubicin) after 24 hours and 48 hours. The percent growth reduction represents a decrease in cell growth compared to a control condition. Furthermore, density functional theory (DFT) calculations were utilized to examine the frontier molecular orbitals (FMOs) and overall chemical reactivity descriptors of TAJ1. The molecule's chemical reactivity and stability were assessed by determining the HOMO-LUMO energy gap. TAJ1 displayed a HOMO energy level of -0.224 eV, a LUMO energy level of -0.065 eV, and a HOMO-LUMO gap of 0.159 eV. Additionally, molecular docking analysis was performed to assess the binding affinities of TAJ1 with various proteins. The compound TAJ1 showed potent interactions with NEK2, exhibiting -10.5 kcal mol-1 binding energy. Although TAJ1 has demonstrated interactions with NEK7, NEK9, TP53, NF-KAPPA-B, and caspase-3 proteins, suggesting its potential as a therapeutic agent, it is important to evaluate the conformational stability of the protein-ligand complex. Hence, molecular dynamics simulations were conducted to assess this stability. To analyze the complex, root mean square deviation (RMSD) and root mean square fluctuation analyses were performed. The results of these analyses indicate that the top hits obtained from the virtual screening possess the ability to act as effective NEK2 inhibitors. Therefore, further investigation of the inhibitory potential of these identified compounds using in vitro and in vivo approaches is recommended.

Design, Synthesis, Molecular Docking, and In Vitro Antibacterial Evaluation of Benzotriazole-Based β-Amino Alcohols and Their Corresponding 1,3-Oxazolidines

In the present study, a series of benzotriazole-based β-amino alcohols were efficiently synthesized in excellent yields via aminolysis of benzotriazolated epoxides under catalyst- and solvent-free conditions. Further these β-amino alcohols were successfully utilized to synthesize the corresponding benzotriazole-based oxazolidine heterocyclic derivatives. All the synthesized compounds were characterized by various spectroscopic techniques such as 1H NMR, 13C NMR, and mass spectroscopy for structure elucidation. The compounds were subjected to a microtiter plate-based antimicrobial assay. The antimicrobial activity results reveal that the compounds 4a, 4e, and 5f were found to be active against Staphylococcus aureus (ATCC-25923) with minimum inhibitory concentrations (MICs) of 32, 8, and 64 μM, respectively. Also, the compounds 4a, 4e, 4k, 4i, 4m, 4n, 4o, 5d, 5e, 5f, 5g, and 5h showed effective activity against Bacillus subtilis (ATCC 6633) with MICs of 64, 16, 16, 16, 64, 16, 64, 64, 32, 64, 8, and 16 μM, respectively. A biological investigation was conducted, including molecular docking of two compounds with several receptors to identify and confirm the best ligand-protein interactions. Hence, this study found a significant strategy to diversify the chemical molecules. The synthesized compounds play a potential role as an antibacterial intensifier against some pathogenic bacteria for the development of antibacterial substances.

Electrochemical C(sp2)-H/N-H "formal" cross-dehydrogenative coupling of olefins with benzotriazoles for synthesis of N-vinyl benzotriazoles

The paper details an electrochemical method that couples olefins with benzotriazoles to form C(sp2)-N bonds, enabling the synthesis of N-vinyl benzotriazoles in moderate to good yields. nBu4NI functions as both an electrolyte and an iodine mediator, and the method does not require oxidants or metals. It is a highly atom-economical and clean reaction, with hydrogen as the sole byproduct.

Identifying antimicrobials and their metabolites in wastewater and surface water with effect-directed analysis

This study aimed to identify antimicrobial contaminants in the aquatic environment with effect-directed analysis. Wastewater influent, effluent, and surface water (up- and downstream of the discharge location) were sampled at two study sites. The samples were enriched, subjected to high-resolution fractionation, and the resulting 80 fractions were tested in an antibiotics bioassay. The resulting bioactive fractions guided the suspect and nontargeted identification strategy in the high-resolution mass spectrometry data that was recorded in parallel. Chemical features were annotated with reference databases, assessed on annotation quality, and assigned identification confidence levels. To identify antibiotic metabolites, Phase I metabolites were predicted in silico for over 500 antibiotics and included as a suspect list. Predicted retention times and fragmentation patterns reduced the number of annotations to consider for confirmation testing. Overall, the bioactivity of three fractions could be explained by the identified antibiotics (clarithromycin and azithromycin) and an antibiotic metabolite (14-OH(R) clarithromycin), explaining 78% of the bioactivity measured at one study site. The applied identification strategy successfully identified antibiotic metabolites in the aquatic environment, emphasizing the need to include the toxic effects of bioactive metabolites in environmental risk assessments.

Design, Synthesis, and Antiviral Activities of New Benzotriazole-Based Derivatives

Several human diseases are caused by enteroviruses and are currently clinically untreatable, pushing the research to identify new antivirals. A notable number of benzo[d][1,2,3]triazol-1(2)-yl derivatives were designed, synthesized, and in vitro evaluated for cytotoxicity and antiviral activity against a wide spectrum of RNA positive- and negative-sense viruses. Five of them (11b, 18e, 41a, 43a, 99b) emerged for their selective antiviral activity against Coxsackievirus B5, a human enteroviruses member among the Picornaviridae family. The EC50 values ranged between 6 and 18.5 μM. Among all derivatives, compounds 18e and 43a were interestingly active against CVB5 and were selected to better define the safety profile on cell monolayers by transepithelial resistance test (TEER). Results indicated compound 18e as the hit compound to investigate the potential mechanism of action by apoptosis assay, virucidal activity test, and the time of addition assay. CVB5 is known to be cytotoxic by inducing apoptosis in infected cells; in this study, compound 18e was proved to protect cells from viral infection. Notably, cells were mostly protected when pre-treated with derivative 18e, which had, however, no virucidal activity. From the performed biological assays, compound 18e turned out to be non-cytotoxic as well as cell protective against CVB5 infection, with a mechanism of action ascribable to an interaction on the early phase of infection, by hijacking the viral attachment process.

Thermochemistry, Tautomerism, and Thermal Stability of 5,7-Dinitrobenzotriazoles

Nitro derivatives of benzotriazoles are safe energetic materials with remarkable thermal stability. In the present study, we report on the kinetics and mechanism of thermal decomposition for 5,7-dinitrobenzotriazole (DBT) and 4-amino-5,7-dinitrobenzotriazole (ADBT). The pressure differential scanning calorimetry was employed to study the decomposition kinetics of DBT experimentally because the measurements under atmospheric pressure are disturbed by competing evaporation. The thermolysis of DBT in the melt is described by a kinetic scheme with two global reactions. The first stage is a strong autocatalytic process that includes the first-order reaction (Ea1I = 173.9 ± 0.9 kJ mol−1, log(A1I/s−1) = 12.82 ± 0.09) and the catalytic reaction of the second order with Ea2I = 136.5 ± 0.8 kJ mol−1, log(A2I/s−1) = 11.04 ± 0.07. The experimental study was complemented by predictive quantum chemical calculations (DLPNO-CCSD(T)). The calculations reveal that the 1H tautomer is the most energetically preferable form for both DBT and ADBT. Theory suggests the same decomposition mechanisms for DBT and ADBT, with the most favorable channels being nitro-nitrite isomerization and C–NO2 bond cleavage. The former channel has lower activation barriers (267 and 276 kJ mol−1 for DBT and ADBT, respectively) and dominates at lower temperatures. At the same time, due to the higher preexponential factor, the radical bond cleavage, with reaction enthalpies of 298 and 320 kJ mol−1, dominates in the experimental temperature range for both DBT and ADBT. In line with the theoretical predictions of C–NO2 bond energies, ADBT is more thermally stable than DBT. We also determined a reliable and mutually consistent set of thermochemical values for DBT and ADBT by combining the theoretically calculated (W1-F12 multilevel procedure) gas-phase enthalpies of formation and experimentally measured sublimation enthalpies.

Recent advances in the chemistry of aryltriazene

Triazene is one of the most versatile building blocks in organic synthesis. Generally, it is viewed as a safe equivalent of diazonium salt, thus immediately finding numerous applications in preparative chemistry and medicinal chemistry. Besides, it can be used as a removable directing group in C-H functionalization or play a smart role as a precursor for aryl cation/radical generation. In this review, we will highlight recent noteworthy developments in this field.

Advances in the synthesis of nitrogen-containing heterocyclic compounds by in situ benzyne cycloaddition

Nitrogen-containing heterocyclic compounds are prevalent in various natural products, medicines, agrochemicals, and organic functional materials. Among strategies to prepare nitrogen-containing heterocyclic compounds, pathways involving benzyne intermediates are attractive given that they can readily assemble highly diverse heterocyclic compounds in a step-economical manner under transition-metal-free conditions. The synthesis of nitrogen-containing heterocyclic compounds from benzyne intermediates offers an alternative strategy to the conventional metal-catalyzed activation approaches. In the past years, chemists have witnessed the revival of benzyne chemistry, mainly attributed to the wide application of various novel benzyne precursors. The cycloaddition of benzynes is a powerful tool for the synthesis of nitrogen-containing heterocyclic compounds, which can be constructed by [n + 2] cyclization of benzyne intermediates in situ generated from benzyne precursors under mild reaction conditions. This review focuses on the application of cycloaddition reactions involving in situ benzynes in the construction of various nitrogen-containing heterocyclic compounds.

Evaluation of Ruthenium(II) N-Heterocyclic Carbene Complexes as Enzymatic Inhibitory Agents with Antioxidant, Antimicrobial, Antiparasitical and Antiproliferative Activity

A series of [RuCl₂(p-cymene)(NHC)] complexes were obtained by reacting [RuCl₂(p-cymene)]2 with in situ generated Ag-N-heterocyclic carbene (NHC) complexes. The structure of the obtained complexes was determined by the appropriate spectroscopy and elemental analysis. In addition, we evaluated the biological activities of these compounds as antienzymatic, antioxidant, antibacterial, anticancer, and antiparasitic agents. The results revealed that complexes 3b and 3d were the most potent inhibitors against AchE with IC₅₀ values of 2.52 and 5.06 μM mL^-1. Additionally, 3d proved very good antimicrobial activity against all examined microorganisms with IZ (inhibition zone) over 25 mm and MIC (minimum inhibitory concentration) < 4 µM. Additionally, the ligand 2a and its corresponding ruthenium (II) complex 3a had good cytotoxic activity against both cancer cells HCT-116 and HepG-2, with IC₅₀ values of (7.76 and 11.76) and (4.12 and 9.21) μM mL^-1, respectively. Evaluation of the antiparasitic activity of these complexes against Leishmania major promastigotes and Toxoplasma gondii showed that ruthenium complexes were more potent than the free ligand, with an IC₅₀ values less than 1.5 μM mL^-1. However, 3d was found the best one with SI (selectivity index) values greater than 5 so it seems to be the best candidate for antileishmanial drug discovery program, and much future research are recommended for mode of action and in vivo evaluation. In general, Ru-NHC complexes are the most effective against L. major promastigotes.

Natural Product-Oriented Photo-Induced Denitrogenative Annulations of 1-Alkenylbenzotriazoles

The photo-induced denitrogenative annulations of a variety of 1-alkenylbenzotriazoles were investigated. By judiciously manipulating the structural variations of 1-alkenylbenzotriazoles, two characteristic polycyclic skeletons associated with monoterpene indole alkaloids were constructed through a diverted and controllable manner. The present work not only enriches the photochemistry of 1-alkenylbenzotriazoles, but also offers a unified approach to access skeletally diverse indole alkaloid scaffolds.

QSAR, molecular docking, molecular dynamics and MM-GBSA approach for identification of prospective benzotriazole-based SARS-CoV 3CL protease inhibitors

The 3CL Protease of severe acute respiratory syndrome coronavirus (SARS-CoV), responsible for viral replication, has emerged as an essential target for designing anti-coronaviral inhibitors in drug discovery. In recent years, small molecule and peptidomimetic inhibitors have been used to target the inhibition of SARS-CoV 3CL Protease. In this study, we have developed 2D and 3D Quantitative structure activity relationship (QSAR) models on 3CL protease inhibitors with good predictive capability to propose inhibitors with improved affinities. Based on the 3 D contour maps, three new inhibitors were designed in silico, which were further subjected to molecular docking to explore their binding modes. The newly designed compounds showed improved interaction energies toward SARS-CoV-3CLPro due to additional interactions with the active site residues. The molecular docking studies of the most potent compounds revealed specific interactions with Glu 166 and Cys 145. Furthermore, absorption, distribution, metabolism, elimination (ADME) and drug-likeness evaluation revealed improved pharmacokinetic properties for these compounds. The molecular dynamics simulations confirmed the stability of the interactions identified by docking. The results presented would guide the development of new 3CL protease inhibitors with improved affinities in the future.Communicated by Ramaswamy H. Sarma.

Novel Benzotriazole Acetamide Derivatives as Benzo-Fused Five- Membered Nitrogen-Containing Heterocycles - In silico Screening, Molecular Docking, and Synthesis

Background:

DNA gyrase subunit B (1KZN) is an attractive target for antibacterial drug development because of its role in DNA replication. The fast development of antimicrobial medication resistance necessitates the quick discovery of new antimicrobial medicines.

Objective:

The goal of this research was to design, synthesize, and discover benzo-fused five-membered nitrogen-containing heterocycles that bind to DNA gyrase subunit B via molecular docking (1KZN).

Methods:

Based on literature research, 2-(1H-1,2,3-Benzotriazol-1-yl)-N-substituted acetamide was synthesized using an efficient method. All synthesized compounds were evaluated for antibacterial activity against three distinct organisms: E. coli, Pseudomonas aeruginosa, Staphylococcus aureus. In a docking investigation, the chemical interacts with the active site of DNA gyrase subunit B (1KZN), indicating that it might have antibacterial action.

Conclusion:

According to the findings of this research, the compounds 3d and 3f showed antibacterial properties. For Staphylococcus aureus, 3c has the potential to be an antibacterial agent.

Promising heterocycle-based scaffolds in recent (2019-2021) anti-Alzheimer's drug design and discovery

Alzheimer's disease (AD) is one of the neurodegenerative diseases that led to morbidity and mortality world-wide. It is a complex disease whose etiology is not completely known that leads to difficulty in prevent or cure of the AD. Also, there are only few approved drugs for AD treatment. Apart from deaths due to AD, expenditure of treatment and care of AD patients is higher than that of treatment of HIV and cancer diseases combined. Hence, it leads to an economic burden also. Although research is being carried out on designing drugs for AD, most of them have ended up in poor inhibitors with high toxicity. Hence, researchers should shoulder a great responsibility of discovery of efficient drugs for AD treatment. In the field of drug discovery, heterocycles played an important role. Also, most of the heterocyclic scaffolds have been used in design of potent anti-AD agents. In view of this, heterocyclic molecules reported recently are compiled and evaluated comprehensively. Especially, the molecules which exhibited pronounced activity are emphasized and described with respect to structure-activity relationship (SAR) in brief.

Methylene-Tethered Arylsulfonation and Benzotriazolation of Aryl/Heteroaryl C-H Bonds with DMSO as a One-Carbon Surrogate

The Selectfluor-mediated approach toward the synthesis of methylene-tethered arylsulfonation and benzotriazolation of imidazopyridines has been described. The reaction involves imidazopyridine, aryl sulfinate, or benzotriazole and dimethyl sulfoxide (DMSO) in the presence of Selectfluor, where DMSO acts as a one-carbon synthon. The protocol has been extended to the methylene-tethered arylsulfonation and benzotriazolation of β-naphthols. The mechanistic insights show that the intermediate 3-((methylthio)methyl)-2-phenylimidazo[1,2-a]pyridine is generated from imidazopyridine, DMSO, and Selectfluor. The nucleophilic displacement by the aryl sulfinate salt or benzotriazole on the intermediate afforded the product.

Highly Stable Univalent Copper of a Cu@Al/SBA-15 Nanocomposite Catalyzes the Synthesis of Fluorescent Aminobenzotriazoles Derivatives

With the development of green chemistry, it is still a challenge to maintain the unstable valence state of the metal in heterogeneous catalysts and realize new catalytic synthesis methods. In this paper, it is reported that an univalent copper nanocomposite (Cu@Al/SBA-15) can efficiently catalyze the formation of novel amino-containing benzotriazoles with great fluorescence properties in a new synthetic strategy. Subsequently, its application is further verified by an acylation reaction to produce a series of novel benzotriazoles derivatives with high yield. It is worth noting that the Cu@Al/SBA-15 nanocomposites not only enable the reaction completed with high yield in a short time, but can also be recycled many times without a significant reduction in activity, and the leaching of copper and aluminum species in reaction system is negligible. Finally, the detailed and feasible reaction mechanism is also provided.

Electron Distribution in 1,2,3-Benzotriazole and 1,2,3-Triazole Anion Radical Isomers: An EPR and DFT Study

The anion radicals of N1- and N2-alkylbenzotriazoles and alkyltriazoles (alkyl = methyl or isopropyl) have been generated by low-temperature potassium metal reduction in tetrahydrofuran. Electron paramagnetic resonance (EPR) analysis and density functional theory calculations reveal that the electron spin distribution within the triazole ring of these systems is markedly different. The magnitude of the electron-nitrogen couplings along with the calculated spin densities reveals that the N2-alkylbenzotriazole and N2-alkyltriazole anion radicals have significantly greater electron spin residing within the N₃ portion of the triazole ring compared with that of the respective N1 isomers. These differences impact the overall geometry of the triazole ring where both N2-isomers lose planarity upon reduction. Experimental and computational results reveal that the N2-methyltriazole anion radical has the largest concentration of electron spin residing in the N₃ moiety compared to that of the other three anion radicals studied. Significant anisotropic line broadening is observed in the EPR spectrum of the N2-methyltriazole anion radical, which is a consequence of the large nitrogen hyperfine couplings and sufficiently slow rotational motion of this species in solution.

Design, Synthesis, and Antipoliferative Activities of Novel Substituted Imidazole-Thione Linked Benzotriazole Derivatives

A new series of benzotriazole moiety bearing substituted imidazol-2-thiones at N1 has been designed, synthesized and evaluated for in vitro anticancer activity against the different cancer cell lines MCF-7(breast cancer), HL-60 (Human promyelocytic leukemia), and HCT-116 (colon cancer). Most of the benzotriazole analogues exhibited promising antiproliferative activity against tested cancer cell lines. Among all the synthesized compounds, BI9 showed potent activity against the cancer cell lines such as MCF-7, HL-60 and HCT-116 with IC50 3.57, 0.40 and 2.63 µM, respectively. Compound BI9 was taken up for elaborate biological studies and the HL-60 cells in the cell cycle were arrested in G2/M phase. Compound BI9 showed remarkable inhibition of tubulin polymerization with the colchicine binding site of tubulin. In addition, compound BI9 promoted apoptosis by regulating the expression of pro-apoptotic protein BAX and anti-apoptotic proteins Bcl-2. These results provide guidance for further rational development of potent tubulin polymerization inhibitors for the treatment of cancer.

Trichloroacetimidate-Triggered Expeditious and Novel Synthesis of N-Acylbenzotriazoles

A facile route for the synthesis of a diverse range of N-acylbenzotriazole derivatives from the corresponding carboxylic acids has been established through a carbonyl activation pathway. In this method, trichloroacetonitrile is performed as an effective reagent for an easy access of N-acylbenzotriazoles which was simply proceeded through the activation of carboxylic acids via in situ imidate formation in anhydrous 1,2-dichloroethane followed by addition of 1H-benzotriazole at 80 °C for 3–4 h. Easy handling, one-pot, and metal-free conditions demonstrate the notable merits of the devised protocol.

New Organic Materials Based on Multitask 2H-benzo[d]1,2,3-triazole Moiety

Multifunctionality is a desirable aspect in materials science. Indeed, the development of multifunctional compounds is crucial for sustainable chemistry by saving resources and time. In this sense, 2H-benzo[d]1,2,3-triazole (BTz) is an excellent candidate with promising characteristics, including its ability to self-assemble; its acceptor character, which enables the synthesis of donor-acceptor structures; and its facile modulation using standard chemical methods. Thus, due to its interesting properties, it is possible to produce different derivatives with applications in different fields, as summarized in this article, with the correct substitution at the BTz cores. Optoelectronic or biomedical applications, amongst others, are highlighted.

Synthesis of α,β-unsaturated benzotriazolyl-1,3,4-oxadiazole derivatives: anticancer activity, cytotoxicity, and cell imaging

A series of ten α,β-unsaturated benzotriazolyl-1,3,4-oxadiazole derivatives was synthesized and all compounds were evaluated in vitro against three breast cancer cell lines (MCF-7, MDA-MB-231 and 4T1) at different concentrations (0.1, 0.5, 1, 2, 3, 4 and 5 mg/mL). The results showed that compounds 6a, 6c, 6d, 6f, 6g, and 6i displayed acceptable anticancer activity, where compound 6f was the most active on the three cell lines (IC50 = 0.80, 0.07, and 0.30 mg/mL, respectively). Regarding the cytotoxicity assay, the compounds exhibited modest toxicity on murine splenocytes and peripheral human blood cells at the highest concentration tested (5 mg/mL). Compound 6f was further evaluated at different concentrations showing moderate cytotoxicity at the 5 mg/mL concentration and negligible cytotoxicity at the minimum concentration evaluated (0.05 mg/mL). Finally, the compounds 6a, 6c, 6d, 6f, 6g, 6i, and 6j were evaluated as fluorescence markers due to their ability to be internalized into MCF-7 cells.

B(C6F5)3-Catalyzed site-selective N1-alkylation of benzotriazoles with diazoalkanes

Alkylation of benzotriazoles is synthetically challenging, often leading to mixtures of N1 and N2 alkylation. Herein, metal-free catalytic site-selective N1-alkylation of benzotriazoles with diazoalkanes is described in the presence of 10 mol% of B(C6F5)3. These reactions provide N1-alkylated benzotriazoles in good to excellent yields and this protocol is successfully adapted to gram-scale syntheses as well as a derivative with antimicrobial activity.

Design, synthesis, HER2 inhibition and anticancer evaluation of new substituted 1,5-dihydro-4,1-benzoxazepines

A series of 11 new substituted 1,5-dihydro-4,1-benzoxazepine derivatives was synthesised to study the influence of the methyl group in the 1-(benzenesulphonyl) moiety, the replacement of the purine by the benzotriazole bioisosteric analogue, and the introduction of a bulky substituent at position 6 of the purine, on the biological effects. Their inhibition against isolated HER2 was studied and the structure–activity relationships have been confirmed by molecular modelling studies. The most potent compound against isolated HER2 is 9a with an IC₅₀ of 7.31 µM. We have investigated the effects of the target compounds on cell proliferation. The most active compound (7c) against all the tumour cell lines studied (IC₅₀ 0.42–0.86 µM) does not produce any modification in the expression of pro-caspase 3, but increases the caspase 1 expression, and promotes pyroptosis.

Synthesis and Antiproliferative Evaluation of 2-Deoxy-N-glycosylbenzotriazoles/imidazoles

A series of 2-deoxy-2-iodo-α-d-mannopyranosylbenzotriazoles was synthesized using the benzyl, 4,6-benzylidene and acetyl protected D-glucal in the presence of N-iodosuccinimide (NIS). Subsequent removal of the iodine at the C-2 position using tributyltin hydride under free radical conditions afforded the 2-deoxy-α-d-glucopyranosylbenzotriazoles in moderate to high yields. This method was extended to the preparation of substituted 2-deoxy-β-d-glucopyranosylimidazoles as well. The stereoselectivity of the addition reaction and the effect of the protecting group and temperature on anomer distribution of the benzotriazole series were also investigated. The anticancer properties of the newly synthesized compounds were evaluated in a series of viability studies using HeLa (human cervical adenocarcinoma), human breast and lung cancer cell lines. The N-[3,4,6-tri-O-benzyl-2-deoxy-α-d-glucopyranosyl]-1H-benzotriazole and the N-[3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl]-2H-benzotriazole were found to be the most potent cancer cell inhibitors at 20 µM concentrations across all four cell lines.

Cross-Dehydrogenative N-N Coupling of Aromatic and Aliphatic Methoxyamides with Benzotriazoles

Nitrogen-nitrogen bond containing motifs are ubiquitous in bioactive compounds and organic materials. However, intermolecular hetero-selective N-H/N-H oxidative coupling reactions remain very challenging and largely unexplored. Here, we report an unprecedented, simple and hetero-selective cross-dehydrogenative N-N coupling of amides and benzotriazoles, utilizing only a hypervalent iodine species as the terminal oxidant. The scope and mechanistic investigations are discussed.

Simultaneous determination of low molecule benzotriazoles and benzotriazole UV stabilizers in wastewater by ultrasound-assisted emulsification microextraction followed by GC-MS detection

A rapid, sensitive, economically and ecologically friendly method based on one-step ultrasound-assisted emulsification microextraction and in situ derivatization followed by gas chromatography-mass spectrometry for simultaneous determination of low molecular benzotriazoles and benzotriazole-based ultraviolet filters was developed. The optimized method allows quantification of benzotriazole, 4-methylbenzotriazole, 5-methylbenzotriazole; 5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzortriazole and 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole in municipal and industrial (dairy) wastewater. The method was validated using real influent and effluent wastewater and samples at various stages of the purification process. Relative recoveries obtained using wastewater as sample matrix were between 77 and 137%, method limits of detection from 0.001 to 0.035 µg/L, method limits of quantification from 0.003 to 0.116 µg/L, the repeatability expressed by the coefficient of variation did not exceed 12%. The use of the method for the determination of tested compounds in municipal and industrial wastewater showed their presence in most of the tested samples, in concentrations from LoD to 6.110 µg/L. The conducted studies of samples from municipal wastewater treatment plant located in north-east Poland showed that the effectiveness of benzotriazole removal by this plant wasfrom 29 to 84%. The load of tested compounds released into the environment by this facility ranges from 2 to 269 mg/day/1000 inhabitants.

Synthesis, Antitumor and Antiviral In Vitro Activities of New Benzotriazole-Dicarboxamide Derivatives

Cancer and viral infections continue to threaten humankind causing death worldwide. Hence, the discovery of new anticancer and antiviral agents still represents a major scientific goal. Heterocycles designed to mimic the chemical structure of natural pyrimidines and purines have been designed over the years, exerting their activity acting as false substrates on several different targets. We reported a series of bis-benzotriazole-dicarboxamide derivatives which inhibit viral helicase of poliovirus, and hence we planned structure modifications to obtain different series of new dicarboxamides. Here, the synthesis and characterization of 56 new compounds: 31 bis-benzotriazole dicarboxamides and 25 mono-substituted acidic derivatives are reported. The synthesized compounds were tested for their antiviral and antitumor activity. Mostly, compounds 4a, 4c and 4d showed antiviral activity against tested Picornaviruses, Coxsackievirus B5 and Poliovirus-1. Likewise, four derivatives (3b, 3d, 4d, 9b) showed notable antiproliferative activity inhibiting cell growth in two distinct antitumor screenings. Compound 3b was selected as the antitumor lead compound for the wide range of activity and the potency proved. The lead compound was proved to induce apoptosis in SK-MES1 tumor cells, in a dose-dependent manner.

Hybrid Materials Based on Magnetic Iron Oxides with Benzothiazole Derivatives: A Plausible Potential Spectroscopy Probe

Rare diseases affect a small part of the population, and the most affected are children. Because of the low availability of patients for testing, the pharmaceutical industry cannot develop drugs for the diagnosis of many of these orphan diseases. In this sense, the use of benzothiazole compounds that are highly selective and can act as spectroscopy probes, especially the compound 2-(4'-aminophenyl)benzothiazole (ABT), has been highlighted. This article reports the design of potential contrast agents based on ABT and iron to develop a new material with an efficient mechanism to raise the relaxation rate, facilitating diagnosis. The ABT/δ-FeOOH hybrid material was prepared by grafting (N-(4'-aminophenyl) benzothiazole-2-bromoacetamide) on the surface of the iron oxyhydroxide particles. FTIR spectra confirmed the material formations of the hybrid material ABT/δ-FeOOH. SEM analysis checked the covering of nanoflakes' surfaces in relation to the morphology of the samples. The theoretical calculations test a better binding mode of compound with iron oxyhydroxide. Theoretical findings show the radical capture mechanism in the stabilization of this new material. In this context, Fe³⁺ ions are an electron acceptor from the organic phase.