Copper-Promoted One-Pot Approach: Synthesis of Benzimidazoles

Abstract

A facile, one-pot, and proficient method was developed for the production of various 2-arylaminobenzimidazoles. This methodology is based for the first time on a copper catalyst promoted domino C–N cross-coupling reaction for the generation of 2-arylaminobenzimidazoles. Mechanistic investigations revealed that the synthetic pathway involves a copper-based desulphurization/nucleophilic substitution and a subsequent domino intra and intermolecular C–N cross-coupling reactions. Some of the issues typically encountered during the synthesis of 2-arylaminobezimidazoles, including the use of expensive catalytic systems and the low reactivity of bromo precursors, were addressed using this newly developed copper-catalyzed method. The reaction procedure is simple, generally with excellent substrate tolerance, and provides good to high yields of the desired products.

A directing group switch in copper-catalyzed electrophilic C–H amination/migratory annulation cascade: divergent access to benzimidazolone/benzimidazole

“…All our efforts using different acidic solvents such as AcOH or TFE, acid additives such as BzOH, TsOH, and high temperature (120 °C) to facilitate dehydration after cyclization were in vain. Gratifyingly, the corresponding picolinimidamide afforded the imidazole product in 30% yield in 12 h. Since thioamides have been proved as excellent directing groups in Pd- or Co-catalyzed C–H functionalizations, 23 we hypothesized that thiophilic copper 24 may trigger the liberation of hydrogen sulfide from thioamide instead of 1,2-pyridyl migration to furnish the desired benzimidazole product. Hence, examining thiopicolinamide 4a under the reaction condition resulted in the desired 2-pyridylbenzimidazole exclusively albeit in a low yield.…”

Selective Catalytic Oxidation of Toluene to Benzaldehyde: Effect of Aging Time and Calcination Temperature Using CuxZnyO Mixed Metal Oxide Nanoparticles

“…Hence, based on the above literature reports and in continuation of our studies towards preparation of various catalysts for different conversion reactions [36][37][38][39][40][41][42], in the present work we report the synthesis of Cu x Zn y O mixed oxide by coprecipitation with varied aging time and calcination temperature. The prepared catalysts were characterized by various techniques such as XRD, XPS, FT-IR, TGA, SEM, and TEM.…”

Recent advances in the functionalization of azulene through Rh‐, Ir‐, Ru‐, Au‐, Fe‐, Ni‐, and Cu‐catalyzed reactions

“…Copper has received a lot of attention because it is inexpensive and abundant on the earth. [57] Copper-mediated reactions have a long history that dates back to the classic Glaser coupling. [58][59][60] Copper-mediated reactions have also grown in popularity in recent years.…”