537701-39-6Relevant academic research and scientific papers
Metal-free selective synthesis of 2-substituted benzimidazoles catalyzed by Br?nsted acidic ionic liquid: Convenient access to one-pot synthesis of N-alkylated 1,2-disubstituted benzimidazoles
Senapak, Warapong,Saeeng, Rungnapha,Jaratjaroonphong, Jaray,Promarak, Vinich,Sirion, Uthaiwan
, p. 3543 - 3552 (2019/05/29)
A novel efficient method for the selective synthesis of 2-substituted benzimidazoles is described through condensation reaction of o-phenylenediamines with a wide rang of aliphatic, aromatic and heteroaromatic aldehyde substrates using Br?nsted acidic ionic liquid as a reusable catalyst under metal-free conditions at ambient temperature. Notably, Dodecylimidazolium hydrogen sulfate ([DodecIm][HSO4]) is the most efficient catalyst for good to excellent yields of the corresponding products (up to 98%). Subsequently, this protocol was successfully applied for the preparation of N-alkylated 1,2-disubstituted benzimidazoles in high to excellent yields via sequential one-pot reaction. In addition, catalysts are recycled at least four times without significant loss in activity.
"All-water" chemistry of tandem N-alkylation-reduction- condensation for synthesis of N-arylmethyl-2-substituted benzimidazoles
Kommi, Damodara N.,Kumar, Dinesh,Bansal, Rohit,Chebolu, Rajesh,Chakraborti, Asit K.
, p. 3329 - 3335 (2013/01/16)
A water-assisted tandem N-alkylation-reduction-condensation process has been devised as a new synthetic route for the one-pot synthesis of N-arylmethyl-2-substituted benzimidazoles. Water plays the crucial and indispensable role through hydrogen bond mediated 'electrophile-nucleophile dual activation' in promoting selective N-monobenzylation of o-nitroanilines as an alternative to the transition metal-based chemistry for C-N bond formation (amination) and forms the basis of disposing the substituents on the benzimidazole moiety in regiodefined manner. Water also exerts a beneficial effect in the condensation of N-monobenzylated o-phenylenediamines with aldehydes. The water-assisted C-N bond formation chemistry led to metal/base-free synthesis of N-monobenzylated o-nitroanilines and N-monobenzylated o-phenylenediamines. The indispensable/advantageous role of water in the various stage of the N-alkylation-reduction-condensation process exemplifies an 'all-water' chemistry for the synthesis of N-arylmethyl-2- substituted benzimidazoles.
