Synthesis, characterization, and microwave-promoted catalytic activity of novel benzimidazole salts bearing silicon-containing substituents in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions under aerobic conditions

Abstract

A number of benzimidazole derivatives (1-8) were synthesized and the catalytic activity of these compounds in a catalytic system including Pd(OAc) 2 and K2 CO3 in DMF-H2 O was evaluated in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions of aryl iodides, bromides, and chlorides with styrene and arylboronic acids under microwave irradiation and aerobic conditions. The yields of both the Heck-Mizoroki and the Suzuki-Miyaura cross coupling reactions with aryl iodides and aryl bromides were nearly quantitative. The synthesized 1-substituted benzimidazole (1) and benzimidazole salts (2-8) were identified by 1 Hand 13 C-NMR and IR spectroscopic methods, and micro analysis. The molecular structure of 7 was also determined by X-ray crystallography. Key Words: Benzimidazole salt, N-heterocyclic carbene, palladium catalysis, Heck-Mizoroki coupling