New (NHC)Pd(II)(PPh3) complexes: synthesis, characterization, crystal structure and its application on Sonogashira and Mizoroki–Heck cross-coupling reactions

Design, synthesis, spectroscopic characterizations, single crystal X-ray analysis, in vitro xanthine oxidase and acetylcholinesterase inhibitory evaluation as well as in silico evaluation of selenium-based N-heterocyclic carbene compounds

Herein, eight new NHC-based selenourea derivatives were synthesized and characterized by using spectroscopic method (1H, 19F, and 13C NMR, FT-IR), and elemental analysis techniques. These compounds were synthesized by mixing benzimidazolium salts, potassium carbonate, and selenium powder in ethyl alcohol. Additionally, the molecular and crystal structures of the three compounds (1c, 2b, and 2c) were determined using the single-crystal x-ray diffraction (XRD) method. Diffraction analysis demonstrated the partial carbon-selenium double-bond character of these compounds. All compounds were determined to be highly potent inhibitors for AChE and XO enzymes. The IC50 values for the compounds were found in the range of 0.361-0.754 μM for XO and from 0.995 to 1.746 μM for AChE. The DNA binding properties of the compounds were investigated. These compounds did not have a remarkable DNA binding property. Also, DPPH radical scavenging activities of the compounds were also investigated. Compounds (1c), (2a), (3a), and (3b) exhibited more pronounced DPPH radical scavenging activity when compared to other compounds. Docking studies were applied by using AutoDock 4 to determine interaction mechanism of the selected compounds (1a), (1b), and (3b). The compound (1b) has good binding affinity (-9.78 kcal/mol) against AChE, and (-6.86 kcal/mol) for XO target. Drug similarity properties of these compounds compared to positive controls were estimated and evaluated by ADMET analysis. Furthermore, molecular dynamics simulations have been applied to understand the accuracy of docking studies. These findings and the defined compounds could be potential candidates for the discovery and progress of effective medicine(s) for AChE and XO in the future.Communicated by Ramaswamy H. Sarma.

The palladium-based complexes bearing 1,3-dibenzylbenzimidazolium with morpholine, triphenylphosphine, and pyridine derivate ligands: synthesis, characterization, structure and enzyme inhibitions

The palladium-based complexes bearing N-heterocyclic carbene (NHC) ligand have long attracted attention as active catalysts for many catalytic reactions. Recently, the biological activities of these complexes, which are stable to air and moisture, have also been wondered. With the aim, we report the synthesis of a series of (NHC)Pd(Br₂)(L) complexes (NHC: 1,3-dibenzylbenzimidazolium, L: morpholine, triphenylphosphine, pyridine, 3-chloropyridine, and 2-aminopyridine). All complexes were characterized by NMR (¹H and ¹³C), FTIR spectroscopic and elemental analysis techniques. In addition, the single crystal structures of the complex 3, 4, and 6 were determined through single crystal x-ray crystallographic method. Furthermore, the carbonic anhydrase I and II isoenzymes (hCAs) and acetylcholinesterase (AChE) inhibition effects of these palladium-based complexes bearing NHC ligand were investigated. They showed highly potent inhibition effect with K_i values are between 10.06 ± 1.49–68.56 ± 11.53 nM for hCA I isoenzyme, 7.74 ± 0.66 to 49.39 ± 6.50 nM for hCA II isoenzyme and 22.83 ± 3.21 to 64.09 ± 9.05 nM for AChE enzyme.

A Palladium-Free Sonogashira Coupling Protocol Employing an In Situ Prepared Copper/Chelating 1,2,3-Triazolylidene System

A new, palladium-free Sonogashira coupling reaction protocol using a catalytic system that comprises a simple, cheap, widely available copper salt and a chelating 1,2,3-triazolylidene ligand precursor is reported. This protocol provides the desired coupling products in moderate to very good yields.

Preparation of aromatic γ-hydroxyketones by means of Heck coupling of aryl halides and 2,3-dihydrofuran, catalyzed by a palladium(ii) glycine complex under microwave irradiation

The synthesis of phenyl-γ-hydroxyketones through Heck coupling and subsequent opening of the tetrahydrofuran ring by the nucleophilic attack of a water molecule catalyzed by PdCl₂·Gly₂ under microwave irradiation.