Use of bis(benzimidazolium)–palladium system as a convenient catalyst for Heck and Suzuki coupling reactions of aryl bromides and chlorides

Abstract

Six new, sterically demanding bis(benzimidazolium) salts (2a-f) as NHC precursors have been synthesized and characterized. These salts, in combination with palladium acetate, provide active catalysts for the cross-coupling of aryl chlorides and bromides under mild conditions in aqueous media.

Palladium(II)NHC complexes containing benzimidazole ligand as a catalyst for CN bond formation

“…The chemical shift of the C2 carbon at 143.5, 143.1 and 143.3 ppm is in agreement with data reported for other benzimidazolium salts. [13,17,31] The IR spectra of all the salts show strong C-N bands at around 1567, 1571 and 1595 cm −1 as expected.…”

Microwave-Assisted Synthesis of Novel Perimidinium Salts as N-Heterocyclic Carbene Precursors: Involvement in Palladium-Catalyzed Cross-Coupling Reactions

“…These signals are consistent with general acidic proton shift of the related imidazolium and benzimidazolium salts. 17,18 IR spectra of compounds 2a-e support the proposed structure, signals at 1656-1667 cm -1 indicate the presence of -N=C-N-group in the structure.…”

“…13 Strong electron-donating ability of NHC ligands give their metal complexes stability to heat, air, and moisture. [14][15][16][17][18][19] Since the early 90s, various NHC ligands have been reported.…”

“…As NHC precursor, imidazolium, 14,15 imidazolinium, 16,17 and benzimidazolium 18,19 scaffolds were used intensively, and very active catalytic systems were prepared with not only palladium but also with various transition metals. In spite of the rapid development of the synthesis of NHC complexes and their application in catalytic reactions, perimidine-based NHC's were not studied sufficiently due to difficulties of producing of perimidine derivatives compared with five-membered analogs.…”

Synthesis and characterizations of N,N′‐bis(diphenylphosphino)‐2‐(aminomethyl)aniline derivatives: application of a palladium(II) complex as pre‐catalyst in Heck and Suzuki cross‐coupling reactions

“…Recently, the Suzuki reaction of aryl chlorides catalyzed by palladium-tertiary phosphine [36] systems has been studied extensively due to the the economically attractive nature of the starting materials. In order to survey the reaction parameters for the catalytic Suzuki reaction, we examined Cs 2 CO 3 , K 2 CO 3 and K t OBu as base and DMF and dioxane as solvent.…”