Journals / Turkish Journal of Chemistry / 2013 / Cilt: 37 - Sayı: 5

Synthesis of novel benzimidazole salts and microwave-assisted catalytic activity of in situ generated Pd nanoparticles from a catalyst system consisting of benzimidazol salt, Pd(OAc) 2 , and base in a Suzuki-Miyaura reaction

Synthesis of novel benzimidazole salts and microwave-assisted catalytic activity of in situ generated Pd nanoparticles from a catalyst system consisting of benzimidazol salt, Pd(OAc)2, and base in a Suzuki-Miyaura reaction

Pages
721–733
DOI
—

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/K2CO3 in DMF/H2O. 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 13C NMR and IR spectroscopic methods, and micro analysis. The molecular structure of 5 was also determined by X-ray crystallography.

Özet

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/K2CO3 in DMF/H2O. 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 13C 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