Band 27, Heft 1

In the present study, 3- p -methoxybenzyl/ m -chlorobenzyl/phenyl-4-(3-methyl-2-thienylmethyleneamino)-4,5-dihydro-1 H -1,2,4-triazol-5-ones were obtained from the reaction between 3-methylthiophene-2-carbaldehyde and three different 4-amino-(3- p -methoxybenzyl/ m -chlorobenzyl/phenyl)-4,5-dihydro-1 H -1,2,4-triazole-5-ones. In order to compare experimental and theoretical values, the geometric parameter, electronic, nonlinear optical properties, molecular electrostatic potentials and spectroscopic properties of 3-substituted-4-(3-methyl-2-thienylmethyleneamino)-4,5-dihydro-1 H -1,2,4-triazol-5-ones have been simulated. The electronic properties of the newly synthesized compounds were calculated using DFT/B3LYP and DFT/B3PW91 methods revealing parameters such as ionization potential, electron affinity, energy gap, electronegativity, molecular hardness, molecular softness, electrophilic index, nucleophilic index and chemical potential, all obtained from HOMO and LUMO energies, dipole moments and total energies. UV-visible absorption spectra and the stimulation contributions in UV-visible transitions were obtained by using TD-DFT/B3LYP/6-311G(d,p) and TD-DFT/B3PW91/6-311G(d,p) methods in ethanol. The calculated absorption wavelengths, oscillator power and excitation energies were compared with experimental values. In line with DFT, the numbers of molecular vibration were analyzed through the basis set of 6-311G(d,p). The recording of FT-IR frequencies was done for the pertinent compound. The recorded frequencies through DFT/B3LYP and DFT/B3PW91 methods were compared to experimental values, with a result gained closest to the values of B3LYP. Finally, the Gaussian09W program package in DMSO phase, starting from the optimized structure, has been instrumental in calculating the 13 C-NMR and 1 H-NMR chemical shift values of the GIAO method.

A Cu(II)-catalyzed Csp 2 -Se and Csp 2 -Sulfur bond formation was achieved with moderate to good yields without the aid of Lewis acid and base. The reaction is compatible with a wide range of heterocycles such as benzothiazole, thiazole, and imidazole. Also, this typical protocol is found to be active in thio-selenation via S-H activation. Additionally, we proposed a plausible mechanistic pathway involving Cu(III) putative intermediate.

In this work, a novel C(sp 3 )–C(sp 2 ) cross-dehydrogenative-coupling method is developed to react benzoxazin-2-one derivatives with various indoles. As a result, combined use of ball milling and Fe( ii ) catalysis leads to rapid coupling of 1,4-benzoxazinones with derivatives of indole. Under the conditions, derivatives of 1 couple with various indoles at room temperature to produce good yields of the desired compounds within 0.5–2 h time period. Thus, derivatives of both starting materials couple smoothly under relatively mild conditions to give good yields of 3 .

In this work, magnetic nanoparticle-supported sulfonic acid (γ-Fe 2 O 3 -SO 3 H) is used as an efficient catalyst in the synthesis of 2,4,5-trisubstituted imidazoles and 1,2,4,5-tetrasubstituted imidazoles in a short time (40–70 min for trisubstituted imidazoles and 30–40 min for tetrasubstituted imidazoles) and high-purity products were obtained (92–98% for trisubstituted imidazoles and 94–98% for tetrasubstituted imidazoles) in simple multicomponent reactions. The structure of these products was confirmed via FT-IR and NMR. Green and recyclable catalysts, eco-friendly and solvent-free conditions, high catalytic activity, shorter reaction time, easy recovery by an external magnet, high purity, and excellent yields are some features of these reactions. Graphical abstract

In this study, a series of azobenzothiazole dyes 4 were synthesized via diazotization of substituted benzothiazole derivatives followed by azo coupling with acetaminophen. The chemical structures of all synthesized compounds were confirmed using analytical data and spectroscopic techniques, including UV-visible, IR, mass spectra, and 1 H- and 13 C-NMR. The in situ formed diazobenzothiazole ions regiospecifically react with acetaminophen derivatives in the Hollemann-guided electrophilic aromatic substitution mechanism. The regio-orientations were established, on the one hand, by a rigorous interpretation of 1 H-NMR spectra and, on the other hand, by the characteristic fragmentation patterns observed on the electrospray mass spectra. In the cases of 4a and 4b, multisubstitutions occurred. The antimicrobial activity of compound 4 , along with all the starting materials, was investigated on Pseudomonas aeruginosa PA01, Staphylococcus aureus 18, Escherichia coli 64R, and S. aureus ATCC 25923. The results showed that this skeletal framework exhibited marked potency as antibacterial agents. The most active antibacterial agent against both targeted organisms was compound 4a′ .

A new series of benzo[5,6]chromeno[3,2- c ]quinoline derivatives were successfully synthesized using various arylglyoxal monohydrates, quinoline-2,4-dione, and β-naphthol in H 2 O:EtOH (2:1) as a green solvent in the presence of catalytic amounts p -toluenesulfonic acid as a mild catalyst under reflux conditions with high yields (83–92%). The reaction conditions were optimized in different solvents at variable thermal conditions, and the optimized reaction condition for this synthesis has been reported. The structures of all new products were defined by 1 H-NMR, 13 C-NMR, FT-IR, mass spectral data, and HRMS. Graphical abstract

4-Amino-5-methyl-2,4-dihydro-3 H -1,2,4-triazol-3-one (1) was converted to the corresponding Schiff base (2) by treatment with salicylaldehyde. 1,2,4-Triazoles were then converted to the corresponding Mannich bases containing fluroquinolone core using a one-pot three-component procedure. Moreover, the synthesis of six compounds, which can be considered as conazole analogues, was performed starting from 1,2,4-triazole-3-one compounds via three steps by either conventional or microwave-mediated conditions. All the newly synthesized compounds were screened for their antimicrobial activities. Most exhibited good to moderate antibacterial and/or antifungal activity. The structural assignments of the new compounds were based on elemental analysis and spectral (IR, 1 H NMR, 13 C NMR, and LC-MS) data.

In this study, the structure of 4-[4-(diethylamino)-benzylideneamino]-5-benzyl-2 H -1,2,4-triazol-3(4 H )-one (DBT) was examined through spectroscopic and theoretical analyses. In this respect, the geometrical, vibrational frequency, 1 H and 13 C-nuclear magnetic resonance (NMR) chemical shifts, thermodynamic, hyperpolarizability, and electronic properties including the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energies of DBT as a potential non-linear optical (NLO) material were investigated using density functional theory at the B3LYP level with the 6-311G basis set. 1 H and 13 C-NMR chemical shifts of DBT with the gauge-invariant atomic orbital and continuous set of gauge transformation methods (in the solvents) were estimated, and the computed chemical shift values displayed excellent alignment with observed ones. Time-dependent density-functional theory (TD-DFT) calculations with the integral equation formalism polarizable continuum model within various solvents and gas phases in the ground state were used to evaluate UV-vis absorption and fluorescence emission wavelengths. Thermodynamic parameters including enthalpy, heat capacity, and entropy for DBT were also calculated at various temperatures. Moreover, calculations of the NLO were carried out to obtain the title compound’s electric dipole moment and polarizability properties. To illustrate the effect of the theoretical method on the spectroscopic and structural properties of DBT, experimental data of structural and spectroscopic parameters were used. The correlational analysis results were observed to indicate a strong relationship between the experimental and theoretical results. Graphical abstract

The present study aimed to design and synthesize a series of phenyl-isoxazole-carboxamide derivatives and investigate their antitumor and antioxidant activities. The in vitro cytotoxic evaluation was conducted using the MTS assay against four cancer cell lines: hepatocellular carcinoma (Hep3B and HepG2), cervical adenocarcinoma (HeLa), breast carcinoma (MCF-7), in addition to the normal cell line (Hek293T). Besides, the antioxidant activity was evaluated using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. All obtained compounds were found to have potent to moderate activities against Hep3B and MCF-7 cancer cells lines, except compound 2e . It was found that compound 2a has potent activity against HeLa and Hep3B cancer cell lines with IC 50 values of 0.91 and 8.02 µM, respectively. The IC 50 dose range of the tested compounds against Hep3B was 5.96–28.62 µM, except for 2e , compared with doxorubicin, which has an IC 50 value of 2.23 µM. Also, the IC 50 value range of the compounds against Hek293T was 112.78–266.66 µM, compared with doxorubicin, which has an IC 50 dose of 0.581 µM. The antioxidant activity of the synthesized compounds was weak, and compound 2d showed moderate activity against the DPPH enzyme with an IC 50 value of 138.50 µM in comparison with Trolox, which has an IC 50 dose of 37.23 µM.

In the present research, we focus on the energetics and electronic aspects of enhanced reactivity in the regioselective bioorthogonal 1,3-dipolar cycloaddition reaction of various substituted cyclooctynes with methyl azide, applying quantum chemistry approaches. In this respect, we assessed the structural and energetic properties of regioisomeric products and their corresponded transition states and calculated the reaction electronic energy changes and energy barriers through the cycloaddition pathways. The obtained results revealed that the trifluoromethyl substitution and fluorination of cyclooctynes lead to improved reactivity, in conjunction with increased exothermicity and decreased activation energy values. On the other hand, quantum theory of atoms in molecules computations were performed on some key bond and ring critical points that demonstrated the stabilizing topological properties of electron density and its derivatives upon trifluoromethyl substitution and fluorination of propargylic carbon of cyclooctynes which can be regarded as the essential origin of enhanced reactivity.

In this study, quantum chemical calculations of phenazine-based organic molecules applied in organic dye-sensitized solar cells (DSSCs) have been made and interpreted. Since DSSC molecules work with the electron push–pull system, the sequence of other compounds (2–8) from compound 1 is designed as a donor–π bridge (weak acceptor)–acceptor (D–π–A). Later, the studied molecules were expanded from 2a to 8c by lengthening the conjugation with phenyl, thiophene, and furan to the acceptor parts. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are practiced to investigate all structures and absorption spectra of molecules, respectively. It has been observed that the phenazine-based molecule series are good candidates for DSSCs, both with their band gap and their absorption spectrum results. It can be assumed that changing the HOMO and LUMO energy values of all designed structures according to compound 1 can absorb light in the organic dye-sensitized solar cells and transfer electrons to the conductivity band of TiO 2 . As a result, it has been resolved that various dyes can be designed for dye-sensitizing solar cells by calculating electronic energies, HOMO–LUMO energies, and absorption wavelengths.

Three different reactions were explored leading to the synthesis of various benzofurans. All reactions took place under AcOH catalysis in a one-pot manner. As a result, benzoquinone derivatives underwent heteroannulation with either itself or cyclohexanones to produce furanylidene-benzofuran or benzofuran structures, respectively.

In recent years, ALR2 (aldose reductase) inhibitors have attracted attention for their effective ability to reduce the progression of diabetes-associated cataracts. Therefore, in the present article, we intended to develop novel thiazole-sulfonamide hybrids as a potent inhibitor of ALR2. These molecules significantly inhibited the ALR2 level in the rat lenses homogenate, where the most potent compound 7b showed activity comparable to sorbinil as standard. In Wistar rats, compound 7b improved the insulin level and body weight of the experimental animal together with a reduction in the glucose output. Compound 7b showed a significant reduction in the expression of ALR2 in rat lenses in western blot analysis.

Organic electrochemistry is a technique that allows for the heterogeneous redox reactions avoiding both the use of stoichiometric amounts of redox reagents and the resulting formation of stoichiometric by-products. In fact, the redox reagent in these reactions is the electron, which is naturally eco-friendly and produces no side compounds. It is therefore quite obvious that electrochemistry can be classified as a “green” technology. The use of this methodology in the synthesis of β-lactams is not a novelty, but the growing interest in this class of biologically active compounds, due to the discovery of new fields of application (after a moment of decrease in interest due to antibiotic resistance) has been a stimulus for the search for more efficient electrochemical ways to synthesize and transform β-lactams. Thus, this review deals with the twenty-first-century applications of electroorganic technique to the chemistry of β-lactams, by analyzing first the syntheses classified by the type of reactions (cyclization, cycloaddition, etc.) and then by manipulating the β-lactam structure, using it as a synthon. Lastly, the importance of this technique is demonstrated by a study of a pilot plant scale reduction of a cephalosporanic acid derivative to a commercially important antibiotic.

This mini-review encapsulates the latest findings (past 10 years) in the field of the deep eutectic solvents (DESs) application in the alkylation/arylation of different heterocyclic compounds. These solvents have been developed to fulfill the green chemistry concept demands and have been proven excellent for the application in various fields. This review describes their application in different types of alkylation, C -, N -, O - and S -alkylation. P -alkylation has not yet been published within this scope. Not only have the authors in this study proven that DESs could be successfully applied for this specific type of reaction, but they have also offered an excellent insight into the mechanisms of their action.