Derivatives 2a-c Research Articles

Anti-proliferative activities of 4H-pyran derivatives synthesized from benzoylacetone

ABSTRACT. Benzoylacetone (1) underwent a series of multi-component reactions with aromatic aldehydes and malononitrile or ethyl cyanoacetate to produce the pyran derivatives 4a-f. The latter compounds reacted with malononitrile or ethyl cyanoacetate to yield the condensation products 5a-m. On the other hand, the reaction of 4a-f with either the diazonium salts 6a-c yielded the arylhydrazone derivatives 7a-i. The multi-component reaction of (1) with aromatic adehydes and cyclohexan-1,3-dione produced the pyran derivatives 9a-c. Compound 1 underwent the Gewald’s reactions with elemental sulfur and malononitrile or ethyl cyanacetate yielding the thiophene derivatives 10a,b. Evaluations of the synthesized products were carried out against some selected cancer cell lines and the most active compounds were further evaluated against the seventeen cancer cell lines classified according to the disease. Morphological changes of A549 cell line by the effect of compound 7k was studied using microenvironment of the lung tissue where an excellent results was obtained.
 
 KEY WORDS: Benzoylacetone, Multi-component reactions, Pyran, Thiophene, Arylhydrazone, Cytotoxicity
 
 Bull. Chem. Soc. Ethiop. 2023, 37(2), 405-425. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i2.12

Chemical Constituents of Macaranga occidentalis, Antimicrobial and Chemophenetic Studies.

Medicinal plants are known as sources of potential antimicrobial compounds belonging to different classes. The aim of the present work was to evaluate the antimicrobial potential of the crude extract, fractions, and some isolated secondary metabolites from the leaves of Macaranga occidentalis, a Cameroonian medicinal plant traditionally used for the treatment of microbial infections. Repeated column chromatography of the ethyl acetate and n-butanol fractions led to the isolation of seventeen previously known compounds (1-17), among which three steroids (1-3), one triterpene (4), four flavonoids (5-8), two stilbenoids (9 and 10) four ellagic acid derivatives (11-14), one geraniinic acid derivative (15), one coumarine (16), and one glyceride (17). Their structures were elucidated mainly by means of extensive spectroscopic and spectrometric (1D and 2D NMR and, MS) analysis and comparison with the published data. The crude extract, fractions, and isolated compounds were all screened for their antimicrobial activity. None of the natural compounds was active against Candida strains. However, the crude extract, fractions, and compounds showed varying levels of antibacterial properties against at least one of the tested bacterial strains, with minimal inhibitory concentrations (MICs) ranging from 250 to 1000 μg/mL. The n-butanol (n-BuOH) fraction was the most active against Escherichia coli ATCC 25922, with an MIC value of 250 μg/mL. Among the isolated compounds, schweinfurthin B (10) exhibited the best activity against Staphylococcus aureus NR 46003 with a MIC value of 62.5 μg/mL. In addition, schweinfurthin O (9) and isomacarangin (6) also exhibited moderate activity against the same strain with a MIC value of 125 μg/mL. Therefore, pharmacomodulation was performed on compound 6 and three new semisynthetic derivatives (6a-c) were prepared by allylation and acetylation reactions and screened for their in vitro antimicrobial activity. None of the semisynthetic derivatives showed antimicrobial activity against the same tested strains. The chemophenetic significance of the isolated compounds is also discussed in this paper.

Design of an efficient three component one-pot synthesis of -1,2,3,4-tetrahydro-4-oxo-6-(5-substituted 2-phenyl-1H-indol-3-yl)-2-thioxopyrimidine-5-carbonitrile as antimicrobial and antitubercular agent

In the present study, a novel, rapid, improved and eco-friendly synthesis of indolyl-pyrazolo-pyrimidine derivatives 4a-c by using conventional method via one-pot multi-component reaction has been described. The structures of all these unknown compounds have been confirmed with the help of physical and spectroscopic techniques like IR, 1H and 13C NMR and mass spectrometry and these newly synthesized compounds have been evaluated for in vitro antimicrobial and antitubercular and antioxidant activities. The results reveal that compound 4a exhibits promising antimicrobial, antitubercular and antioxidant properties when compared to the standard drugs.

Design, synthesis, molecular docking and biological evaluation of β-carboline derivatives as cholinesterase inhibitors

A set of novel β-carboline derivatives were designed and subjected to virtual screening studies by molecular docking in AChE. Among the compounds investigated, derivatives 1a-c, 2a, 3d-f and 4d,e showed lower scores than donepezil (reference compound) and reproducibility in Autodock and Autodock Vina programs. These derivatives were synthesized and evaluated in vitro against AChE and BuChE. The derivatives 4d and 4e displayed the highest inhibition of AChE, with IC50 values of 3.2 ± 0.4 µM and 4.8 ± 0.1 µM, respectively, while 1a-c were the best inhibitors of BuChE, displaying IC50 values of 0.6, 0.9 and 0.8 µM, respectively. Kinetic studies indicated that 1a and 4d are AChE inhibitors of mixed type, and BuChE inhibitors of mixed and competitive types, respectively. Molecular docking studies showed that 1a and 4d interacted similarly with the peripheral anionic and catalytic active sites of AChE while only 4d exhibited interaction by hydrogen bonding with Ser198 of the catalytic triad of BuChE, which confirmed the modes of inhibition of 1a and 4d obtained in the kinetic studies. Our results demonstrate that the strategies used to design and select novel compounds were efficient in the development of new AChE/BuChE dual-targeted inhibitors.

DFT guided substitution effect on azomethine reactive center in newly synthesized Schiff base aromatic scaffolds; syntheses, characterization, single crystal XRD, Hirshfeld surface and crystal void analyses

This paper aims to unfold the effect of substitution (ring A & B) on reactivity of newly synthesized crystalline azomethine linked aromatic compounds/Schiff bases (3a-c). Condensation reaction between 2-iodo-4-chloro substituted aniline with various suitably substituted aromatic aldehydes under acidic catalyzed reaction conditions gave crystalline compounds (3a-c) in good yields. The synthesized compounds were initially investigated in the solid state by single crystal X-ray crystallography besides other structural characterizations. Possible reactivity of azomethine pharmacophore is explained based on the electronic features of attached substituents on the aromatic rings A and B. DFT calculations further backed up the reactivity profile translated for compounds (3a-c) based on electronic grounds, while mechanistic investigation for further chemical reactivity is unfolded via frontier molecular orbital calculations and transition state predictions. Prominent nucleophilic character based on DFT study has been attributed to the halo i,e., -Cl and -I substituents on aromatic ring (ring A) in all the synthesized derivatives (3a-c) with pronounced effect in 3c due to added nucleophilic behavior depicted by cyano substitution in ring B. However, HOMO orbital energy values for (3a-c) predict electron donor behavior of substituents (-CH3, -N(CH3)2, -C=N) on ring B with higher donation capacity predicted for 3b, thus indicating its oxidation in possible chemical transformations. Hirshfeld surface analysis revealed the prevalence of potential van der Waals interactions and hydrogen bonding as major intermolecular interactions in their (3a-c) crystal packings. In addition, crystal void analyses depicted high mechanical stabilities for (3a-c) due to absence of large cavities in their crystal packings. Moreover, reaction scope guided by the joint DFT and electronic explanations for the effect of substituents used on azomethine linkage has also been proposed/predicted as part of the study.

Recent Advances in the Chemistry and Biological Activity of Sulfonamide Derivatives

Abstract: This review describes different synthetic methods for the preparation of sulfonamides. Generally, sulfonamides are synthesized from sulfonyl chloride derivative and amino derivative. A series of sulfonamide derivatives 7a-c, 8a,b, 9, 10, 11a,b, and 12 were synthesized in alkaline media by reacting different amino compounds with a p-toluene sulfonyl chloride. Different amino derivatives 13, 15, 17, 19, and 21 reacted with p-tolyl sulphonyl chloride to afford sulfonylamides 14, 16, 18, 20, and 22. Different reactions of sulfonamide derivatives have been summarized. Generally, the sulfonamide function group does not participate in any reactions, but other functional groups in the compound are involved in various reactions. Sulfonamides exhibit different biological activities, e.g., antibacterial activity, anticancer activity, urease inhibitory activity, radical scavenging activity, carbonic anhydrase inhibitory activity, non-competitive lactoperoxidase inhibitory activity, antifungal activity, and anti-mycobacterial activity.

Synthesis, characterization, evaluation of metabolic enzyme inhibitors and in silico studies of thymol based 2-amino thiol and sulfonic acid compounds

Eight new aminothiols (4a-g and 5) and three new sulfonic acid derivatives (6a-c) were synthesized, and their structures were characterized. Inhibitory effects of the obtained compounds on carbonic anhydrase I and II isoforms (hCA I and hCA II), butyrylcholinesterase (BChE) and acetylcholinesterase (AChE), enzymes were investigated. The newly synthesized compounds have inhibited hCA I with Kis ranging from 7.11 ± 1.46 nM (6a) to 670.52 ± 300.41 nM (4b) and, hCA II with Kis ranging from 16.83 ± 5.72 nM (6a) to 453.34 ± 208.56 nM (4c). Acetazolamide was employed as the positive control for both hCA isoforms (Ki for hCA I 198.81 ± 14.13 nM and Ki for hCA II 211.42 ± 13.10 nM), and among the new compounds obtained, it was observed that there were compounds that were active at much lower nM levels. All compounds were also evaluated for inhibition of AChE and BChE. They inhibited AChE and BChE enzymes in the range of Ki 5.24 ± 2.27 (6c) - 48.44 ± 21.82 (4g) for AChE and 4.86 ± 0.64 (6c) - 51.75 ± 12.56 (4a) for BChE, and the results were compared with the standard inhibitor Tacrine (Ki: 14.20 ± 8.83 nM toward AChE and Ki: 3.39 ± 1.91 nM for BChE). Cholinesterase (BChE and AChE) inhibitory abilities of all synthesized molecules were also performed in situ and molecular docking and molecular dynamics (MD) simulation studies. The molecular coupling scores of the compounds and the free binding energies calculated by MM/GBSA were found to be compatible. Examining the results obtained from this study shows that it may have the potential to develop new drugs to treat some global patients such as glaucoma and Alzheimer's disease (AD).

Boronate derivatives of damnacanthal: Synthesis, characterization, optical properties and theoretical calculations

The natural anthraquinone Damnacanthal (1) was isolated from the roots of Morinda panamensis and used as a building block in the construction of five fluorescent boronate derivatives (4a–4e). The novel compounds were obtained in moderate yields by the condensation of 1, anthranilic acid (2) and diverse phenylboronic acids (3a–3e) in acetonitrile. Boronate derivatives were fully characterized by 1H, 13C, 11B and 2D nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis), and high-resolution mass spectrometry (HR-MS). The photophysical properties were evaluated in tetrahydrofuran revealing that the optical band gap (Egopt) values increase from 2.54 eV for 4a to 2.65 eV for 4d. The maximum emission wavelength and fluorescence quantum yield (ΦF) of the boron complexes were found to be sensitive to the substituents on the phenyl group attached to the boron atom. The resulting derivatives 4a–4c presented emission bands at approximately 522 nm (ΦF = 0.41, 0.13 and 0.37%, respectively); while derivatives 4d and 4e presented broad emission bands with maxima at 676 nm (ΦF = 6.27%) and 614 nm (ΦF = 0.78%), respectively. The molecular geometry, electronic properties and intramolecular non-covalent interactions of the new molecules were evaluated using density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) methods. The value of the energy gap between the HOMO and LUMO increases from 2.89 eV for 4b, 2.96 eV for 4c, 3.04 eV for 4e, 3.08 eV for 4a to 3.32 eV for 4d. Furthermore, compound 4d showed a higher rotational energy barrier (3.33 kcal/mol) at the dihedral angle N1/B1/C24/C25 than its analogs, due to the F∙∙∙π and F∙∙∙O interactions.

AIEgens-NLOphores coumarin-triphenylamine chalcone derivatives: Synthesis, photophysical properties and DFT computational study

Three coumarin-triphenylamine chalcone derivatives (5a-c) with push-pull structures of type A-π-D and D-π-A-π-D were synthesized, varying the substituent at position 7 of coumarin. The characterization of the final compounds as for the intermediates was conducted using 1H and 13C NMR, FT-IR, and HRMS. The study of the photophysical properties of 5a-c revealed a strong solvatochromism, mainly in fluorescent emission, due to the formation of a twisted intramolecular charge transfer (TICT) state. Moreover, aggregation-induced emission (AIE) in MeCNH2O mixtures was notably observed, as well as a strong red emission in the solid state. Computational studies by DFT methods allowed to elucidate the molecular geometries of the ground (S0) and excited states (S1), assign vibrational modes and electronic transitions of IR and UV–Vis spectra, respectively, to describe the reactivity and the electronic distribution from the molecular electrostatic potential (MEP) and the HOMO-LUMO orbitals. Computationally calculated first and second-order hyperpolarizabilities show chalcones 5a-c as potential NLO materials.

Novel 1,2-Thiazine-Pyridine Hybrid: Design, Synthesis, Antioxidant Activity and Molecular Docking Study

Background and Objectives:1,2-thiazine and pyridine heterocycles drew much attention due to their biological activities, including antioxidant activity. Based on fragment-based drug design, novel pyrido[1,2]thiazines 9a-c, thiazolidinopyrido[1,2], thiazines 10a-c and azetidinopyrido[1,2]thiazines 11ac were designed and prepared.Methods:These novel derivatives 9a-c, 10a-c and 11a-c were subjected to screening for their antioxidant activity via various assays as DPPH radical scavenging potential, reducing power assay and metal chelating potential.Results:All the assayed derivatives exhibited excellent antioxidant potential and the tested compounds 9a, 9b, 10a, 10b, 11a and 11b exhibited higher DPPH scavenging potential (EC50 = 32.7, 53, 36.1, 60, 40.6 and 67 μM, respectively) than ascorbic acid (EC50 = 86.58 μM). While targets 9a, 10a and 11a (RP50 = 52.19, 59.16 and 52.25 μM, respectively) exhibited better reducing power than the ascorbic acid (RP50 = 84.66 μM). The computational analysis had been utilized to prophesy the bioactivity and molecular properties of the target compounds.Conclusion:To predict the binding manner of the novel derivatives as antioxidants, in-silico docking study was performed on all the newly prepared compounds inside superoxide dismutase (SOD) and catalase (CAT) active site. The most active antioxidant candidate 9a (EC50 = 32.7 μM, RP50 = 52.19 μM) displayed excellent binding with Lys134 amino acid residing at Cu-Zn loop of SOD with binding energy score = -7.54 Kcal/mol, thereby increasing SOD activity and decreasing reactive oxygen species.

Novel coumarin derivatives as multifunctional anti-AD agents: Design, synthesis, X-ray crystal structure and biological evaluation

With the increasing aging of the population, the rational drug design for the treatment of Alzheimer's disease (AD) has become an important research area. Based on the multi-target design strategy, three coumarin derivatives 3a-3c were designed, synthesized and characterized by 1H NMR, 13C NMR and MS. The biological results showed that they had strong inhibition and high selectivity on acetylcholinesterase (AChE). Compound 3a had the strongest inhibitory effect on AChE (IC50 = 4.28 ± 0.22 µM). And all compounds could inhibit the self-induced and Cu2+-induced aggregation of β-amyloid (Aβ1-42), especially 3a had the best inhibitory effect on the self-aggregation of Aβ1-42 with the ratio of 64.27%. In addition, all compounds showed good antioxidant activity, which might be related to their hydroxyl groups. The compounds had good metal chelating ability, and could selectively chelate Cu2+, Al3+, Fe3+, Fe2+, and Zn2+ ions. Notably, the single crystals of 3b−Cu(II) complex [Cu2(C17H19N2O4)2Cl2]·2CH3OH were prepared and X-ray diffracted for the first time. X-ray crystallography analysis of 3b−Cu(II) complex provided a reliable structure-activity insight about the anti-oxidative and Aβ1-42 disaggregation activities. Furthermore, the results of docking study were consistent with the results of in vitro experiments. 3a-3c were predicted to have good blood brain barrier permeability and ADMET properties. Overall, 3a showed the best activity and might be a promising anti-AD agent.

Synthesis, molecular modeling and antioxidant screening of new thioether-bridged thiadiazole and thiadiazolopyrimidine analogues

The N-aryl-2-((5-(2-cyanoacetamido)-1,3,4-thiadiazol-2-yl)thio)acetamide derivatives 3a-c were prepared and successfully reacted with N,N-dimethylformamide dimethyl acetal (DMF-DMA). The resulting N-thiadiazolyl-2-cyano-3-(dimethylamino)acrylamide derivatives 4a-c were cyclized in boiling acetic acid to yield the corresponding thiadiazolopyrimidine compounds 5a-c. The structural properties of synthesized compounds were studied using DFT/B3LYP level. The HOMO-LUMO energies were employed in determination of some chemical reactivity descriptors. Despite the close energy gap values (ΔEH-L) of the investigated compounds, the data showed that chloro derivatives has the highest energy gap while the methoxy derivatives were the lowest. The synthesized compounds were investigated to explore their antioxidant activities. The results showed that the N-thiadiazolyl-2-cyano-3-(dimethylamino)acrylamides 4a-c had higher inhibition IC50 values (24.27–31.64 µg/mL) than the thiadiazolyl cyanoacetamides 3a-c (34.26–39.33 µg/mL). However, thiadiazolopyrimidines 5a-c presented moderate inhibition with (IC50 = 40.21–44.19 µg/mL) in comparison to ascorbic acid and BHT (Butylated hydroxytoluene) as reference drugs with IC50 = 22.66 and 27.24 µg/mL, respectively. Furthermore, the synthesized compounds were evaluated against (PDB Code-3ML5) using the MOE operation v10.2015.10 database. The inspected synthesized thiadiazole derivatives 3, 4 and 5 revealed H-bond linkages over the receptor through the disparate polar amino acids (Thr 200, Thr 199, Gln 67, His 94, and Lys 91) of larger pocket size of 3ML5. The results of the docking study presented a remarkable agreement with the practical results of the antioxidant activity.

Synthesis, Cytotoxic Effect Assessment and Molecular Docking Studies of Disubstituted Thiadiazole Including Oxadiazole as Hybrid Component

Oxadiazole and thiadiazole are of interest building blocks used in drug design. Considering importance of mentioned scaffolds some of the thiadiazole-oxadiazolederivatives were synthesized by three steps in this study.Firstly, thiol functions of 2-amino-5-mercapto-1, 3, 4-thiadiazole was alkylated by benzyl chloride derivatives to give compounds (1a-c). The reaction of chloroacethylchloride with amine group of compounds (1a–c) terminates to amide derivatives(2a-c). Definitive products were produced by treatment of corresponding amide derivatives with 5-(4-chlorophenyl)-1, 3, 4-oxadiazole-2-thiol.Synthesized compounds were evaluated by MTT assay against two cell lines. The final molecules were docked in the active sites of the epidermal growth factor receptor tyrosine kinase to assay the possible interactions.Final products showed range of cytotoxic activity of moderate to good against tested cell lines. Compound (3a) demonstrated a higher cytotoxic activity against MCF-7 (IC50: 26 µM) and Lncap (IC50: 37 µM) cell lines in comparison with other compounds. The highest docking score was -10.55kcal/mol for compound3a.

Thiophene Ring-Opening Reactions IV. Facile Generation of Novel Ethyl 4-hydroxy-6-thioxonicotinate-1,3,4-thiadiazoline Hybrids

: A set of triethylammonium 4-oxo-6-pyridinethiolate–1,3,4-thiadiazoline hybrids (3a-e) were prepared via the reaction of ethyl 2-chloro-6-cyclopropyl-3- nitro-4-oxothieno[2,3-b]pyridine- 5-carboxylate (2) with the appropriate thiobenzoyl- hydrazide (1a-e) in acetonitrile and triethylamine. These hybrids were readily converted, under neutral mild conditions, into the corresponding 4-hydroxy-6-thioxopyridine –thiadiazoline hybrids (5a-e). The structures of the latter set are supported by HRMS, 1H NMR, and 13C NMR spectral data and further confirmed by single-crystal X-ray diffraction studies. Alkylation of these hybrids in the presence of triethylamine occurred exclusively at the 6-thioxosulfur, yielding the respective 6-sulfanyl derivatives (6a-c).

Cyclization Reactions of Non-Conjugate Ynones with Propargyl Amine in the Presence of a Catalyst

In this study, acetate derivatives were obtained from the reaction of acetophenones using diethyl carbonate. The acidic proton of CH2 moiety was abstracted using a suitable base and α-propargyl-β-ketoester (non-conjugated ynone) derivatives 3a-c were obtained from the reaction of the acetate derivatives with propargyl bromide. By removing the ester group of α propargyl-β-ketoester derivatives under suitable conditions, α-propargyl acetophenones (non-conjugated ynone) 4a-c were obtained. In this study, 6 different unconjugated ynone derivatives were synthesized as starting material with yield in a range of 60-95%. Cyclization reactions with propargyl amine in the presence of three different unconjugated ynone derivatives, metal catalysts were investigated. The synthesis of propargyl pyrroles 7a-c having substituents on C-2 and C-5 was completed.

Design, Synthesis, and Biological Evaluation of Novel Trifluoromethoxy Substituted Pyrazolines as Potential Tubulin Assembling Inhibitors

Breast cancer is a major health problem with an increasing number of cases over the years. Few classes of anticancer agents have been developed but they established toxic effects on normal cells. Despite the availability of many effective drugs to treat different types of cancers, chemotherapeutic drugs are unable to distinguish between healthy and cancerous cells, resulting in the risk of side effects and drugs resistance. There is a continuous effort to find new agents to help bring this disease under control. In this study, novel fluorinated pyrazolines derivatives (2a-c) were designed and synthesized via cyclo-condensation reaction of commercially available trifluoromethoxy phenylhydrazine with a series of chalcone derivatives (1a-c). These pyrazoline compounds, 2a-c exhibited inhibitory activity against MCF-7 cell lines with the IC50 values of 7.62 ± 0.69, 29.61 ±1.60 and 14.38 ± 0.69 μM, respectively. These values are comparable to the positive control, Doxorubicin (IC50 of 17.44 ± 5.32 μM). Pyrazoline 2a exhibited the best free binding energy of-10.8 kcal/mol compared to pyrazoline 2b and 2c which showed the free binding energy of-8.6 and-9.5 kcal/mol, respectively. Molecular docking results of pyrazoline 2a exhibited good interaction between OCF3 moiety with EGFR active site, forming three π bonds which enhanced the anticancer activity. Therefore, pyrazoline 2a would provide promising access to future studies as a potential antitumor agent. Keywords: Fluorinated compounds, trifluoromethoxy, pyrazoline derivatives, molecular modelling, anticancer activity

Multi-component reactions of cyclohexan-1,3-dione to synthesize heterocyclic derivatives with c-Met enzymatic activity, anti-prostate, anti-proliferative and tyrosine kinase activities

ABSTRACT. We are aiming in this work to synthesize target molecules not only possess anti-tumor activities but also kinase inhibitors. The target molecules were obtained starting from aryl hydrazones of cyclohexan-1,3-dione followed by its heterocyclization reactions to produce anticancer molecules. The multi-component reactions of the arylhydrazocyclohexan-1,3-dione derivatives 3a-c produced the 1,4,5,6,7,8-hexahydroquinoline derivatives 6a-r and the 4,5,6,8-tetrahydrochromeno[2,3-c]pyrazole derivatives 10a-c. Other multi-component reactions were demonstrated. The anti-proliferative activity of the synthesized compounds toward the six cancer cell lines namely A549, H460, HT-29, MKN-45, U87MG, and SMMC-7721 was studied. In addition the c-Met enzymatic activities and inhibition toward the prostate cancer cell PC-3 were measured. The results obtained in most cases, indicated that the presence of electronegative Cl group through the molecule favour the inhibitions.
 
 KEY WORDS: Multi-component reactions, Cyclohexan-1,3-dione, Chromene, Chromeno[2,3-c]pyrazole, Cytotoxicity
 
 Bull. Chem. Soc. Ethiop. 2022, 36(1), 119-136. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i1.11 

Synthesis of Benzhydrol Derivatives as Antituberculosis Agents via Fries Rearrangement Method Investigated by DSC Analysis

Benzhydrol derivatives 2a-c were synthesized, and evaluated for antituberculosis activities. These compounds were prepared from corresponding phenyl benzoates through Fries rearrangement and reduction reaction. Fries rearrangement reaction was chosen to use due to its convenient non-solvent method for synthesis. In order to determine the effective temperature for Fries rearrangement reaction, the reaction mixtures of phenyl benzoates 4a-c and AlCl3 heated at constant rates were studied using DSC analysis. DSC curves of those mixtures showed that the reactions started at endothermic temperature ranging from 130 to 140 °C. The optimum temperatures for the synthesis of Fries rearrangement products 5a-c with high %yields were observed at 130, 140, and 130 °C, respectively. The DSC data were effectively applied for the estimation of the optimal reaction temperatures to attain high %yields for the synthesis of benzhydrols. The final benzhydrol derivatives 2a-c were structurally elucidated by FT-IR, 1H NMR, and LC-MS and evaluated for antituberculosis activities by agar-dilution method. It was found that 4-hydroxy-α-(4ʹ-fluorophenyl) benzyl alcohol 2a possessed the highest activity in the series with the minimum inhibitory concentration (MIC) of 40 µg/mL.

Supramolecular self-assembly mediated aggregation-induced emission of fluorene-derived cyanostilbenes: multifunctional probes for live cell-imaging.

The first discovery of aggregation-induced emission (AIE), whereby luminogen aggregation plays a positive role in enhancing the light-emission efficiency, has piqued the interest of many researchers as it opens up a new avenue for the exploration of practically beneficial luminescent materials. Diverse AIE-active luminogens (or AIEgens) with tunable emission colours and very high quantum yields (up to unity) in the solid state have been extensively utilised in a broad range of fields including optoelectronics, energy and bioscience. In this article, we describe novel fluorene-based fluorogens that exhibit bright emission in the solid-state, mechanical stimuli-responsive optical properties and aggregation-induced emissive ability, and were able to modulate their donor and acceptor properties. The target compounds were synthesized by a Knoevenagel condensation followed by Suzuki cross-coupling reaction, which tends to result in good yields. The target cyanostilbenes (4a-4d) show different reversibly switched states with high contrast through morphology modulation and demonstrate solvatochromic, vapochromic, and AIE properties. These results strongly suggest that compound 4d has better properties than the other derivatives (4a-c) due to the presence of extended donor-acceptor ability. Moreover, density-functional theory (DFT) calculations strongly support the UV-Vis and fluorescence spectral studies. The formation of nano-flakes and cuboid-shaped nanocrystals was further confirmed by FE-SEM and AFM studies. The synthesized compound 4d displayed very bright emission in the solid state and in the aggregate state as compared with the other derivatives (4a-4c). These results might be due to the presence of high-color contrast, which is an advantage for elucidation and overcomes the challenges exhibited in live-cell imaging applications. Moreover, an MTT assay on live A549 cells incubated with the target compound (4d) showed very low cytotoxicity even at high concentrations.

Nano Cu2O catalyzed ultrasonic-assisted green synthesis of some seleno[2,3-b] quinoline derivatives

In this report, copper (I) oxide (Cu2O) nanocatalyst was synthesized by chemically reducing a copper precursor with ascorbic acid (AA) and trisodium citrate (TSC) in alkali medium. The influence of Cu2O NPs on the developmental production of selenoquinoline derivatives (5a-c) under room temperature, thermal (80 °C), and different sonication conditions (power, irradiation time, catalyst loading, and other copper salts) was examined. The results indicated that increasing the ultrasonic power (300 W) for short time (60 min), the yield of seleno[2,3-b] quinoline derivatives (5a-c) improved to more than 95%. A proposed mechanism of this approach has been explained. Furthermore, the catalytic system can be recycled without affecting yields or reaction rates significantly. The main features of this protocol are the use of mild reaction conditions, no production of side products, easy work-up, and high yields.