Synthesis, characterization and microwave‐assisted catalytic activity of novel benzimidazole salts bearing piperidine and morpholine moieties in Heck cross‐coupling reactions

Abstract

A mixture of novel benzimidazole salts (2a-f), Pd(OAc) 2 and K 2 CO 3 in DMF-H 2 O catalyzes, in high yield, the Heck crosscoupling reaction assisted by microwave irradiation in a short time. All synthesized novel benzimidazole derivatives were characterized by elemental analysis and NMR spectroscopy. In addition, the molecular structure of 2a was determined by X-ray crystallography.

Potential N‐Heterocyclic Carbene Precursors in the Palladium‐Catalyzed Heck Reaction

“…For the benzimidazolium salts 2a – c , it was found to be 142.5, 142.8, and 142.2 ppm, respectively. These values are in good agreement with the previously reported results .…”

“…The compounds ( 1a–c and 2a–c ) show IR absorption bands at wavelengths and that vary from 1550 to 1658 cm −1 , which are assigned to ν (CN). These IR absorption values are in good agreement with previously reported values for NHC salts .…”

“…However, using the Pd(OAc) 2 ‐catalytic systems containing ligands has been shown more effective catalytic activity than ligand‐free palladium‐containing systems . Pd(OAc) 2 ‐benzimidazole or imidazoline ligands could be very effective catalytic systems, particularly in cross‐coupling reactions . Heck reactions are most frequently performed in dipolar aprotic organic solvents such as DMF , DMA , and dioxane .…”

Synthesis, microwave-promoted catalytic activity in Suzuki-Miyaura cross-coupling reactions and antimicrobial properties of novel benzimidazole salts bearing trimethylsilyl group

“…The catalytic yield of the coupling is dependent on a variety of parameters such as temperature, solvent, base and nature of catalyst loading. We recently reported the optimum reaction conditions for the Suzuki/Heck coupling reaction, including some benzimidazolium or bis‐benzimidazolium saltsPd(OAc) 2 and base as a catalyst system under microwave and conventional heating conditions 27, 53, 54. In the present report, a series of aryl chloride and aryl bromide were used for coupling partner with phenylboronic acid.…”

Efficient and green catalytic system incorporating new benzimidazolium salts for the Sonogashira cross‐coupling reaction

“…[22,23] In our previous studies, we used several in situ prepared palladium-N-heterocyclic carbenes derived from benzimidazole for the Suzuki, Heck and Buchwald-Hartwig reactions under microwave irradiation conditions and obtained promising catalytic results. [24][25][26][27][28][29][30] The use of a metal catalyst as nanoparticles generally accelerates the catalytic conversion and the use of nanoparticles in cross-coupling reactions has attracted a great deal of interest because of their effectiveness. Therefore, several studies have been reported relating to the use of palladium nanoparticles in cross-coupling reactions.…”