A Palladium Catalyst System for the Efficient Cross-Coupling Reaction of

Abstract

New benzimidazolium salts 1a-c and their palladium bis-N-heterocyclic carbene complexes 2a-c and palladium PEPPSI-type complexes 3a-c were designed, synthesized and structurally characterized by NMR (H-1 and C-13), IR, DART-TOF mass spectrometry and elemental analysis. Then these complexes 2-3 were employed in the Suzuki-Miyaura cross-coupling reaction of substituted arenes with phenylboronic acid under mild conditions in toluene and DMF/H2O (1/1) to afford functionalized biaryl derivatives in good to excellent yields. The antibacterial activity of palladium bis-N-heterocyclic carbene complexes 2a-c and palladium PEPPSI-type complexes 3a-c was measured by disc diffusion method against Gram positive and Gram negative bacteria. Compounds 2a, 2c and 3a-c exhibited potential antibacterial activity against four bacterial species among the five used indicator cells. The product 2b inhibits the growth of the all five tested microorganisms. Moreover, the antioxidant activity determination of these complexes 2-3, using 2.2-diphenyl-1-picrylhydrazyl (DPPH) as a reagent, showed that compounds 2a-c and 3b possess DPPH antiradical activity. The higher antioxidant activity was obtained from the product 2b which has radical scavenging activity comparable to that of the two used positive controls (gallic acid GA and tutylatedhydroxytoluene BHT). Investigation of the anti-acetylcholinesterase activity of the studied complexes showed that compounds 2b, 3a, and 3b exhibited moderate activity at 100 g/mL and product 2b is the most active.

C1 [Lamia, Boubakri; Hallouma, Bilel; Hamdi, Naceur] Univ Carthage, Higher Inst Environm Sci & Technol, Res Lab Environm Sci & Technol LR16ES09, Hammam Lif 2050, Tunisia.

[Chakchouk-Mtibaa, Ahlem; Mellouli, Lotfi] Ctr Biotechnol Sfax Tunisia, Lab Microorganisms & Biomol, Rd Sidimansour,Km 6 BP 1117, Sfax 3018, Tunisia.

[Mansour, Lamjed] King Saud Univ, Dept Zool, Coll Sci, POB 2455, Riyadh 11451, Saudi Arabia.

[Ozdemir, Ismail; Yasar, Sedat] Inonu Univ, Fac Sci & Art, Dept Chem, TR-44280 Malatya, Turkey.

[Hamdi, Naceur] Qassim Univ, Dept Chem, Coll Sci & Arts, Al Rass 51921, Saudi Arabia.