ABSTRACT
A series of new benzimidazolium halides were synthesized in good yields as unsymmetrical N-heterocyclic carbene (NHC) precursors containing the N-CH2-arene group. The benzimidazolium halides were readily converted into ruthenium(II)-NHC complexes with the general formula [RuCl2(η6,η¹-arene-CH2-NHC)]. The structures of all new compounds were characterized by ¹H NMR (Nuclear Magnetic Resonance), 13C NMR, FT-IR (Fourier Transform Infrared) spectroscopy and elemental analysis techniques. The single crystal structure of one benzimidazole ruthenium complex, 2b, was determined. The complex is best thought of as containing an octahedrally coordinated Ru center with the arene residue occupying three sites, the remaining sites being occupied by a (carbene)C-Ru bond and two Ru-Cl bonds. The catalytic activity of [RuCl2(η6,η¹-arene-CH2-NHC)] complexes was evaluated in the direct (hetero)arylation of 2-phenylpyridine with (hetero)aryl chlorides in water as the nontoxic reaction medium. These results show that catalysts 2a and 2b were the best for monoarylation with simple phenyl and tolyl chlorides. For functional aryl chlorides, 2d, 2e, and 2c appeared to be the most efficient.
Subject(s)
Chlorides/chemistry , Organometallic Compounds/chemistry , Pyridines/chemistry , Ruthenium/chemistry , Water/chemistry , Acids, Heterocyclic/chemistry , Catalysis , Crystallography, X-Ray , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Structure , Spectroscopy, Fourier Transform InfraredABSTRACT
Novel benzimidazolium salts were synthesized as N-heterocyclic carbene (NHC) precursors, these NHC precursors were metallated with Ag2O in dichloromethane at room temperature to give novel silver(I)-NHC complexes. Structures of these benzimidazolium salts and silver(I)-NHC complexes were characterized on the basis of elemental analysis, (1)H NMR, (13)C NMR, IR and LC-MS spectroscopic techniques. A series of benzimidazolium salts and silver(I)-NHC complexes were tested against standard bacterial strains: Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and the fungal strains: Candida albicans and Candida tropicalis. The results showed that benzimidazolium salts inhibited the growth of all bacteria and fungi strains and all silver(I)-NHC complexes performed good activities against different microorganisms.
Subject(s)
Anti-Infective Agents/pharmacology , Benzimidazoles/pharmacology , Silver/chemistry , Anti-Infective Agents/chemistry , Benzimidazoles/chemistry , Candida/drug effects , Enterococcus faecalis/drug effects , Escherichia coli/drug effects , Microbial Sensitivity Tests , Pseudomonas aeruginosa/drug effects , Spectrum Analysis/methods , Staphylococcus aureus/drug effectsABSTRACT
New Pd-NHC complexes have been synthesized and employed for palladium-catalyzed direct arylation of pyrrole derivatives by using electron-deficient aryl chlorides as coupling partners. The desired coupling products were obtained in moderate to good yields by using 1 mol % of these air-stable palladium complexes. This is an advantage compared to the procedures employing air-sensitive phosphines, which have been previously shown to promote the coupling of aryl chlorides with heteroarenes.
