Imidazoles and their Benzo Derivatives: (ii) Reactivity

Efficient FeCl3/SiO2 as heterogeneous nanocatalysis for the synthesis of benzimidazoles under mild conditions

“…It exhibits substantial activity against several viruses such as HIV [15] and herpes (HSV-1) [12]. Methods of synthesis benzimidazole include the reaction between o-aryldiamines and aldehyde in refluxing nitrobenzene [17,20], the condensation of o-aryldiamines with carboxylic acids or their derivatives in the presence of robust acids such as polyphosphoric acid [14] or inorganic acids [8]. Direct concentration of o-aryldiamines and aldehydes is not a good synthetic reaction, as it is well known to yield a complex combination, being 1,2-disubstituted benzimidazoles [5].…”

Polystyrene-supported pyridinium chloroaluminate ionic liquid as a new heterogeneous Lewis acid catalyst for selective synthesis of benzimidazoles

“…In such acidic melts, Al 2 Cl 7 and Al 3 Cl 10 exist, which act as very strong Lewis acids. [25][26][27][28] Another synthetic approach is the condensation of aldehydes with ophenylenediamines, which involves a two-step procedure including the oxidative cyclodehydration of aniline Schiff bases, which are often generated in situ from the reaction of an aldehyde and o-phenylenediamine. Most importantly, they are extremely hygroscopic and labile towards hydrolysis.…”

Nanosized Mn(acac)3 Anchored on Amino Functionalized Silica for the Selective Oxidative Synthesis of 2-arylbenzimidazoles, 2-arylbenzothiazoles and Aerobic Oxidation of Benzoins in Water

“…High profile biological activities of compounds containing benzimidazole and benzothiazole structures has attracted considerable attention for their synthesis. Commonly employed synthesis of benzimidazoles involve the reaction between 1,2-phenylenediamines and carboxylic acids or their derivatives (nitriles, amidates, orthoesters) in the presence of strong acids such as polyphosphoric acid [21] or mineral acids [22] and the thermal or acid promoted cyclization of N-(N-arylbenzimidoyl)-1,4-benzoquinoneimines [23]. The other popular strategies for their synthesis utilize o-nitroanilines as intermediates or resort to direct N-alkylation of an unsubstituted benzimidazole [24][25][26][27].…”