Synthesis, Characterization and Microwave-Promoted Catalytic Activity of Novel N-phenylbenzimidazolium Salts in Heck-Mizoroki and Suzuki-Miyaura Cross-Coupling Reactions under Mild Conditions

Abstract

A number of novel benzimidazolium salts having aryl substituents such as N-phenyl, 4-chlorophenyl and various alkyl substituents were synthesized. Their microwave-assisted catalytic activities were evaluated in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions using a catalytic system consisting of Pd(OAc) 2 /K 2 CO 3 in DMF/H 2 O under mild reaction conditions with consistent high yields, except those of 2-bromopyridine.

The Beneficial Sinergy of MW Irradiation and Ionic Liquids in Catalysis of Organic Reactions

“…A different approach was used by other researchers, that focused on new N-phenylbenimidazolium salts as ILs, while commercial Pd(OAc)2 was the catalyst [78]. Actually, the salts are not liquid and were used in 2 mol % amounts, in solvents as DMF-H2O or EtOH-H2O.…”

Iron(0), rhodium(I) and palladium(II) complexes with p‐(N,N‐dimethylaminophenyl) diphenylphosphine and the application of the palladium complex as a catalyst for the Suzuki–Miyaura cross‐coupling reaction

“…Traditionally, aryl chlorides are less reactive than aryl bromides in Suzuki-Miyaura reactions and generally require more drastic conditions and/or higher catalyst loading. However, there exist a few reports in which microwave heating [49,50] or conventional heating [51,52] methodologies were successfully used to obtain the coupling products in good to excellent yields. Since only negligible amount (10%) of cross-coupling product was obtained using 0.06 mol% of the catalyst (Table 3, entry 1), we increased the catalyst quantity to 0.5 mol% (entry 2); only a slight improvement in the crosscoupling product formation was observed.…”

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

“…37,38 Since the nature, size, and electronic properties of the substituent on the nitrogen atom(s) of the benzimidazole may play a crucial role in tuning the catalytic activity, to find more efficient palladium catalysts we have synthesized a series of new benzimidazolium halides, 1-5 (Scheme), containing benzyl, substituted benzyl, and 3-phenylpropyl moieties, and we aimed to investigate the activity of in situ Pd-carbene based catalytic systems for Suzuki cross-coupling reactions.…”