Authors: ÜLKÜ YILMAZ, HASAN KÜÇÜKBAY, SEVİM TÜRKTEKİN ÇELİKESİR, MEHMET AKKURT, ORHAN BÜYÜKGÜNGÖR
Abstract: Novel benzimidazolium salts having N-benzyl or N-(4-substitutedbenzyl) groups were synthesized and their microwave-promoted catalytic activity for the Suzuki--Miyaura cross-coupling reaction were determined using in situ formed palladium(0) nanoparticles (PdNPs) from a catalytic system consisting of Pd(OAc)_2/K2CO_3 in DMF/H_2O. PdNPs were characterized by X-ray diffraction (XRD) pattern and particle size of in situ generated PdNPs from the Pd(111) plane was determined to be of diameter 19.6 nm by the Debye--Scherrer equation. Moreover, the yield of the Suzuki--Miyaura reactions with aryl iodides and aryl bromides was found to be nearly quantitative. The synthesized benzimidazole salts (1--5) were identified by ^1H and ^{13}C NMR and IR spectroscopic methods, and micro analysis. The molecular structure of 5 was also determined by X-ray crystallography.
Keywords: Benzimidazole salt, N-heterocyclic carbenes, palladium nanoparticles, cross-coupling reaction, Suzuki--Miyaura coupling, microwave
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