Efficient in situ N-heterocyclic carbene palladium(ii) generated from Pd(OAc)₂ catalysts for carbonylative Suzuki coupling reactions of arylboronic acids with 2-bromopyridine under inert conditions leading to unsymmetrical arylpyridine ketones: synthesis, characterization and cytotoxic activities

Abstract

The in situ prepared four component system Pd(OAc)2, 1,3-dialkylbenzimidazolium halides 2a–i and 4a–i, K2CO3 under CO atmosphere catalyses carbonylative cross-coupling reaction of 2-bromopyridine with various boronic acids to yield unsymmetrical arylpyridine ketones.

Novel and efficient bridged bis(N‐heterocyclic carbene)palladium(II) catalysts for selective carbonylative Suzuki–Miyaura coupling reactions to biaryl ketones and biaryl diketones

“…There are limited published articles on the palladium‐catalyzed carbonylative Suzuki–Miyaura coupling reactions of aryl bromides with aryl boronic acid 2,28,60–62 . For instance, the carbonylative Suzuki–Miyaura coupling reactions of aryl boronic acids with 2‐bromopyridine or aryl bromides have been associated with many shortcomings such as high catalyst loading, low yields, and low selectivity.…”

“…For instance, the carbonylative Suzuki–Miyaura coupling reactions of aryl boronic acids with 2‐bromopyridine or aryl bromides have been associated with many shortcomings such as high catalyst loading, low yields, and low selectivity. In addition, these reactions need high in situ loading of phosphines 2,28,60,63 . To our knowledge, Pd(II)‐NHC complexes were not largely reported as catalysts in the carbonylative Suzuki–Miyaura coupling reactions of aryl bromides with boronic acids.…”

Recent Advances in Benzimidazole Based NHC‐Metal Complex Catalysed Cross‐Coupling Reactions**

“…Hamdi et al reported the use of N,N-substituted benzimidazole salts as ligands in the carbonylative Suzuki coupling reactions catalysed by in-situ generated NHC-Pd(II) catalysts (Scheme 16). [49] Aryl boronic acids were coupled with 2bromopyridine under inert conditions to form unsymmetrical aryl pyridine ketones under the optimized reaction conditions of 5 mol% of ligand, Pd(OAc) 2 (2.5 mol%) and K 2 CO 3 (2.0 mmol) in tetrahydrofuran (THF) at 110 °C under CO atmosphere (20 bar). Benzimidazoles with sterically hindered groups gave lower yields and the efficiency of the reaction was found to depend on the nature of the arylboronic acid, which influence the electronic properties of substances on catalytic reaction.…”

Biological Activities of NHC–Pd(II) Complexes Based on Benzimidazolylidene N-heterocyclic Carbene (NHC) Ligands Bearing Aryl Substituents

“…N-heterocyclic carbene ligands have proven to be very useful for designing new metal complexes for catalysis. [38]. All of the benzimidazolium salts used as NHC precursors were prepared similarly by using the published procedures [39,40].…”