Microwave-assisted synthesis of N-alkylated benzotriazole derivatives: Antimicrobial studies

Deleterious effects of benzotriazoles on zebrafish development and neurotransmission: 5-Chloro-benzotriazole versus 1H-benzotriazole

Benzotriazoles are heterocyclic compounds typically presenting a benzene ring fused with a triazole molecule. The industry uses these compounds as anti-corrosion agents and recently, they have been employed in the pharmaceutical industry and in detergent formulations. Benzotriazoles persist in the environment, and water treatment plants cannot degrade them completely. Consequently, these compounds have been detected in rivers, lakes, and drinking water, which makes assessing their safety for the human and aquatic animal populations crucial. Here, we have evaluated and compared how exposure to 1H-benzotriazole or 5-chloro-benzotriazole affect the zebrafish embryo-larval stages. We have determined the acute toxicity, morphometric alterations, and acetylcholinesterase activity on zebrafish embryos, as well as behavioral endpoints using the tail coiling assay. The estimated LC50 of 5-chloro-benzotriazole was 19 mg/L, whereas 1H-benzotriazole caused no mortality. The zebrafish embryos exposed to 20 and 25 mg/L 5-chloro-benzotriazole had decreased hatching rate and exhibited pericardial and yolk sac edemas. Furthermore, the embryo length and eye area were decreased, in contrast with an increased yolk sac after exposure to 20 mg/L 5-chloro-benzotriazole. In turn, 1H-benzotriazole also decreased the eye area of zebrafish embryos, but no other significant morphological alterations were observed. The tail coiling assay showed that the zebrafish embryos increased the percentage of time moving and the number of embryonic movements per minute after exposure to 1H-benzotriazole (15 mg/L) or 5-chloro-benzotriazole (20 and 25 mg/L), indicating that these compounds were potentially neurotoxic. However, acetylcholinesterase activity was not significantly altered in embryos exposed to 1H-benzotriazole, but significantly decreased when exposed to 0.05 mg/L 5-chloro benzotriazole confirming its neurotoxicity at a much lower concentration. Our findings showed that 5-chloro-benzotriazole seems to induce more harmful alterations to zebrafish embryos than 1H-benzotriazole. Nevertheless, 1H-benzotriazole seems to induce a direct effect on eye development for concentrations lower than the ones of 5-chloro-benzotriazole affecting zebrafish embryos.

4-Aminobenzotriazole (ABTA) as a Removable Directing Group for Palladium-Catalyzed Aerobic Oxidative C-H Olefination

4-Aminobenzotriazole (ABTA) was applied as an effective removable directing group (DG) in Pd-catalyzed C-H activation for the first time. Compared with the widely applied pyridine and quinoline analogs, ABTA showed significantly improved reactivity, achieving aerobic oxidative C-H olefination in excellent yields (up to 95% vs <50% with other reported DGs under identical conditions). Using this new strategy, macrocyclization was achieved to give cyclic peptides in good yields with easy ABTA removal under mild conditions, highlighting the promising potential of this new DG.

Crystal structure of trans-bis-[2-(1H-benzotriazol-1-yl)acetato-κO]bis-(ethano-lamine-κ2 N,O)copper(II)

The reaction of 2-(1H-benzotriazol-1-yl)acetic acid (HBTA; C8H7N3O2) and mono-ethano-lamine (MEA; C2H7NO) with CuCl2·2H2O resulted in the formation of the title complex, [Cu(C8H6N3O2)2(C2H7NO)2] or [Cu(BTA)2(MEA)2]. Its asymmetric unit comprises one BTA anion coordin-ating to the Cu2+ cation (site symmetry ) through the carboxyl O atom, and one MEA ligand chelating the metal cation by two heteroatoms (O and N). The equatorial Cu-O and Cu-N bond lengths are similar at 2.029 (1) and 1.980 (2) Å, respectively, while the length of the axial Cu-O bond is considerably greater [2.492 (2) Å], as is typical for Jahn-Teller-distorted systems. An intra-molecular hydrogen bond is present between the hy-droxy group of the MEA ligand and the non-coordinating O atom of the carboxyl-ate group. Inter-molecular hydrogen bonding involving the amino function of the MEA ligand and the carboxyl-ate group results in eight-membered rings with an R 2 2(8) graph-set motif. The mol-ecules are further linked by C-H⋯π inter-actions involving the triazole rings and methyl-ene groups of MEA, thus generating an overall three-dimensional supra-molecular framework.

Antimicrobial and lubrication properties of 1-acetyl-3-hexylbenzotriazolium benzoate/sorbate ionic liquids

1-Acetyl-3-hexylbenzotriazolium cation-based ionic liquids exhibit antimicrobial activities and improve the lubrication properties of lube base oil by reduction of friction and wear.

Benzotriazole: An overview on its versatile biological behavior

Discovered in late 1960, azoles are heterocyclic compounds class which constitute the largest group of available antifungal drugs. Particularly, the imidazole ring is the chemical component that confers activity to azoles. Triazoles are obtained by a slight modification of this ring and similar or improved activities as well as less adverse effects are reported for triazole derivatives. Consequently, it is not surprising that benzimidazole/benzotriazole derivatives have been found to be biologically active. Since benzimidazole has been widely investigated, this review is focused on defining the place of benzotriazole derivatives in biomedical research, highlighting their versatile biological properties, the mode of action and Structure Activity Relationship (SAR) studies for a variety of antimicrobial, antiparasitic, and even antitumor, choleretic, cholesterol-lowering agents.

Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

(1H-Benzo[d][1,2,3]triazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), 1H-benzo[d][1,2,3]triazol-1-yl 4-methylbenzenesulfonate (Bt-OTs), and 3H-[1,2,3]triazolo[4,5-b]pyridine-3-yl 4-methylbenzenesulfonate (At-OTs) are classically utilized in peptide synthesis for amide-bond formation. However, a previously undescribed reaction of these compounds with alcohols in the presence of a base, leads to 1-alkoxy-1H-benzo- (Bt-OR) and 7-azabenzotriazoles (At-OR). Although BOP undergoes reactions with alcohols to furnish 1-alkoxy-1H-benzotriazoles, Bt-OTs proved to be superior. Both, primary and secondary alcohols undergo reaction under generally mild reaction conditions. Correspondingly, 1-alkoxy-1H-7-azabenzotriazoles were synthesized from At-OTs. Mechanistically, there are three pathways by which these peptide-coupling agents can react with alcohols. From (31)P{(1)H}, [(18)O]-labeling, and other chemical experiments, phosphonium and tosylate derivatives of alcohols seem to be intermediates. These then react with BtO(-) and AtO(-) produced in situ. In order to demonstrate broader utility, this novel reaction has been used to prepare a series of acyclic nucleoside-like compounds. Because BtO(-) is a nucleofuge, several Bt-OCH2Ar substrates have been evaluated in nucleophilic substitution reactions. Finally, the possible formation of Pd π-allyl complexes by departure of BtO(-) has been queried. Thus, alpha-allylation of three cyclic ketones was evaluated with 1-(cinnamyloxy)-1H-benzo[d][1,2,3]triazole, via in situ formation of pyrrolidine enamines and Pd catalysis.

Modular synthesis of N-vinyl benzotriazoles

A modular approach to N1-vinyl benzotriazoles by azide-aryne cycloadditions and Julia-Kocienski reactions is described. Reactions of azidomethyl phenyl-1H-tetrazol-5-yl (PT) sulfide with arynes gave methyl(PT-sulfanyl)-substituted benzotriazoles in 68-89% yields. Oxidation of the sulfides to the sulfones gave the benzotriazole-substituted Julia-Kocienski reagents. Olefination reactions of aldehydes and a ketone with reagents derived from benzyne, 2,3-naphthyne, and 4,5-dimethoxybenzyne precursors proceeded to give various N1-vinyl benzotriazole derivatives. Olefination stereoselectivities are tunable for electron-rich aldehydes, but not for electron-deficient aldehydes and alkanals, where they proceed with good to excellent Z-stereoselectivity.

2-(1H-Benzotriazol-1-yl)-1-(furan-2-yl)ethanol

In the title compound, C₁₂H₁₁N₃O₂, the benzotriazole ring system is approximately planar [maximum deviation = 0.008 (1) Å] and its mean plane is oriented at a dihedral angle of 24.05 (4)° with respect to the furan ring. In the crystal, O—H⋯N hydrogen bonds link the mol­ecules into chains along the ac diagonal. π–π stacking between the furan rings, between the triazole and benzene rings, and between the benzene rings [centroid–centroid distances = 3.724 (1), 3.786 (1) and 3.8623 (9) Å] are also observed.

4-[3-(2H-Benzotriazol-2-yl)prop-oxy]-3-methoxy-benzaldehyde

In the title compound, C₁₇H₁₇N₃O₃, the 3-methoxy­benzalde­hyde group and the benzotriazole fragment are connected through a flexible oxypropyl chain. The O—C—C—C torsion angle in the central link is −63.9 (2)°, while the plane of the benzene ring of the 3-methoxy­benzaldehyde substituent forms a dihedral angle of 56.4 (4)° with the benzotriazole plane.

1-[2-(4-Chloro-benz-yloxy)-2-phenyl-ethyl]-1H-benzotriazole

The asymmetric unit of the title compound, C(21)H(18)ClN(3)O, contains two crystallographically independent mol-ecules which differ slightly in the orientations of chloro-benz-yloxy units. In one of the mol-ecules, the phenyl and chloro-phenyl rings are oriented at dihedral angles of 38.09 (6) and 42.15 (6)°, respectively, with respect to the benzotriazole ring [43.23 (6) and 29.80 (6)° in the other mol-ecule]. The dihedral angle between the phenyl and chloro-phenyl rings is 77.63 (6)° in one of the mol-ecules and 72.97 (6)° in the other. The crystal structure is stabilized by weak C-H⋯π inter-actions.

2-(1H-Benzotriazol-1-yl)-1-phenyl-ethanol

In the title compound, C₁₄H₁₃N₃O, the benzotriazole ring is oriented at a dihedral angle of 13.43 (4)° with respect to the phenyl ring. In the crystal structure, inter­molecular O—H⋯N hydrogen bonds link the mol­ecules into chains along the b axis. Aromatic π–π contacts between benzene rings and between triazole and benzene rings [centroid–centroid distances = 3.8133 (8) and 3.7810 (8) Å, respectively], as well as a weak C—H⋯π inter­action involving the phenyl ring, are also observed.

Synthesis of 1-(4-methoxybenzyl)-3-cyclopropyl-1H-pyrazol-5-amine derivatives as antimicrobial agents

A series of novel substituted 1-(4-methoxybenzyl)-3-cyclopropyl-1H-pyrazol-5-amine benzamides 9(a-h) were synthesized to determine their antibacterial and antifungal activities as well as possible structure-activity relationships (SARs) to improve therapeutic efficacy. The pyrazol-5-amine benzamides were screened for their antibacterial activity against standard strains of Gram-positive (Streptococcus pyogenes NCIM 2608, Staphylococcus aureus ATCC 29737, Bacillus subtilis NCIM 2010) and Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 20852, Klebsiella pneumoniae MTCC 618) bacteria by using streptomycin as positive control. They were also tested for their antifungal activities against mycotoxic strains of Fusarium verticillioides, Aspergillus ochraceous, Aspergillus flavus, Alternaria alternata, and Penicillium chrysogenum using nystatin as positive control. Among the synthesized compounds, 9d, 9g, and 9h showed potent antimicrobial activities.

1,2,3-Triazoles

Rapid progress in the synthetic application of benzotriazole derivatives in the last 20 years has resulted in over 1000 scientific papers on the subject. This fact is reflected in Section 5.01.7, which involves almost a half of the volume of this chapter. The section is arranged according to hybridization of the C-α atom and atomic numbers of the atoms in positions β and γ to allow an easy access to the material of interest. Recent discovery of copper catalysis in [3+2] cycloadditions of azides to acetylenes, the so-called ‘click chemistry’, which boosted application of the 1,2,3-triazole derivatives, especially in medicinal chemistry, is presented in Section 5.01.9. From the point of view of practical applications, Section 5.01.11 is organized according to the number, position, and combination of the substituents at the aromatic rings. Another novel feature that has no precedence in the previous editions of Comprehensive Heterocyclic Chemistry is an addition of triazole and benzotriazole complexes with various transitions metals to Section 5.01.4.

Synthesis and in vitro antimicrobial studies of medicinally important novel N-alkyl and N-sulfonyl derivatives of 1-[bis(4-fluorophenyl)-methyl]piperazine

A series of novel substituted 1-[bis(4-fluorophenyl)-methyl]piperazine derivatives (4a-g) and (5h-m) have been synthesized. The synthesized compounds were characterized by IR and 1H NMR. All the synthesized compounds were evaluated in vitro for their efficacy as antimicrobial agents against representative strains of Gram-positive (Staphylococcus aureus ATCC 25953, Streptococcus pneumoniae ATCC 49619, Bacillus cereus 11778, and Bacillus subtilis 6051) and Gram-negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 2853, Proteus vulgaris ATCC 2853, and Salmonella typhi ATCC 9484) by paper disc diffusion and microdilution methods. Among the newly synthesized compounds 4e, 5l, and 5m showed potent antimicrobial activities, when compared to the standard drug.