Synthesis and pharmacological properties of coumarin-chalcones.

New chalcones (2a-e) were prepared by Claisen-Schmidt condensation from 3-acetyl-4-hydroxycoumarin, which was used as a key intermediate in this synthesis. However, we can easily obtain compounds (3a-e) by refluxing chalcone (2a-e) with 4-hydroxycoumarin in the presence of ammonium acetate and glacial acetic acid. Multinuclear NMR (1H and 13C), IR and elemental analysis characterized the structure of the final compound. The antibacterial activity of the obtained products against various bacterial strains was tested in vitro. The antioxidant properties of the same synthesized compounds were also studied using DPPH (2,2-diphenyl-1-trinitrophenylhydrazine) and hydroxyl radical scavenging tests. Furthemore a study was conducted to highlight the nature of the effects produced by screening 2a-e and 3a-e products on colon cancer cell lines (HCT-116) and hepatocellular carcinoma cell lines (HepG-2). Good cytotoxic activity against standard vinblastine was observed for compound 3a. •3-acetyl-4-hydroxycoumarin as a simple coumarinic ketone was modified to coumarins-bonded chalcones.•Modification was performed through two steps reaction.•Final products exhibited free radical scavenging activity and Good cytotoxic.

Plausible PEPPSI catalysts for direct C-H functionalization of five-membered heterocyclic bioactive motifs: synthesis, spectral, X-ray crystallographic characterizations and catalytic activity.

In this study, a series of benzimidazolium salts were synthesized as asymmetric N-heterocyclic carbene (NHC) precursors. Nine novel palladium complexes with the general formula [PdX2(NHC)(pyridine)] were synthesized using benzimidazolium salts in the PEPPSI (Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation) theme. All synthesized Pd(ii) complexes are stable. The synthesized compounds were thoroughly characterized by respective spectroscopic techniques, such as 1HNMR, 13C NMR, FTIR spectroscopy, X-ray crystallography and elemental analysis. The geometric structure of the palladium N-heterocyclic carbene has been optimized in the framework of density functional theory (DFT) using the B3LYP-D3 dispersion functional with LANL2DZ as a basis set. The on/off mechanism of pyridine assisted Pd-NHC complexes made them the best C-H functionalized catalysts for regioselective C-5 arylated products. Five membered heterocyclic compounds such as 2-acetyl furan, furfuryl acetate 2-acetylthiophene and N-methylpyrrole-2-carboxaldehyde were treated with numerous aryl bromides and arylchlorides under optimal catalytic reaction conditions. Interestingly, all the prepared catalysts possessed essential structural features that facilitated the formation of desired coupling products in quantitative yield with excellent selectivity. The arylation reaction of bromoacetophenone was highly catalytically active with only 1 mol% catalyst loading at 150 °C for 2 hours. To check the efficiency of the synthesized complexes, three different five member heterocyclic substrates (2-acetylfuran, 2-acetylthiophen, 2-propylthaizole) were tested with a number of aryl bromides bearing both electron-donating and electron-withdrawing groups on para position. The data in Tables 2-4. Indicated that electron-donating groups on the para position of aryl halide decreased the catalytic conversion while electron-withdrawing groups increased the catalytic conversion this was due to the high nucleophilicity of the electron-donating substituents.

Synthesis, Characterization, Antimicrobial Properties, and Antioxidant Activities of Silver-N-Heterocyclic Carbene Complexes.

The emergence of antimicrobial resistance has become a major handicap in the fight against bacterial infections, prompting researchers to develop new, more effective, and multimodal alternatives. Silver and its complexes have long been used as antimicrobial agents in medicine because of their lack of resistance to silver, their low potency at low concentrations, and their low toxicity compared to most commonly used antibiotics. N-Heterocyclic carbenes (NHCs) are widely used for coordination of transition metals, mainly in catalytic chemistry. In this study, several N-alkylated benzimidazolium salts 2a-j were synthesized. Then, the N-heterocyclic carbene (NHC) precursor was treated with Ag2O to give silver (I) NHC complexes (3a-j) at room temperature in dichloromethane for 48 h. Ten new silver-NHC complexes were fully characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), elemental analysis, and LC-MSMS (for complexes) techniques. The antibacterial and antioxidant activities of salt 2 and its silver complex 3 were evaluated. All of these complexes were more effective against bacterial strains than comparable ligands. With MIC values ranging from 6.25 to 100 g/ml, the Ag-NHC complex effectively showed strong antibacterial activity. Antioxidant activity was also tested using conventional techniques, such as 2, 2-diphenyl-1-picrylhydrazine (DPPH) and hydrogen peroxide scavenging assays. In DPPH and ABTS experiments, compounds 3a, 3b, 3c, 3e, 3g, and 3i showed significant clearance.