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 Brönsted acidic ionic liquid as a reusable catalyst under metal-free conditions at ambient temperature. Notably, Dodecylimidazolium hydrogen sulfate ([DodecIm][HSO4])
2‐Aryl‐1‐arylmethyl‐1H‐benzimidazoles were prepared in excellent yields by the condensation of o‐phenylenediamine with aldehydes under mechanically activated solvent‐free conditions in ballmill using FeCl3·6H2O as the catalyst.
A solid metal–organic catalyst with hydrophobic pockets and Lewis acid centers strongly accelerates the reaction rate for organic reactions. This is exemplified for the cyanosilylation of ketones and for the synthesis of benzimidazoles, for which very high selectivities are obtained. The solid can be recovered and reused and its behavior approaches that of a functional enzyme mimic.
Superoxide Ion Promoted Synthesis of 2-Arylbenzimidazoles from Schiff Bases
作者:Raghvendra S. Raghuvanshi、Virendra P. Yadav、Vinod K. Singh
DOI:10.2174/1570178612666151028210206
日期:2015.12.2
Background: Benzimidazoles exhibit a wide range of biological activities, including antiparasitic,
antiulcer, antihypertensive, antihistaminic, anticancer, antiemetic and antiinflammatory agents.
Methods: Tetraethylammonium superoxide has been generated in situ by the phase transfer reaction of
potassium superoxide and tetraethylammonium bromide in dry dimethylformamide at room temperature
and subsequently allowed to react with a number of Schiff's bases.
Results: The Synthesis of 2-arylbenzimidazoles from Schiff bases using in situ generated tetraethylammonium superoxide
in dry DMF, at room temperature.
Conclusion: The role of in situ generated Et4NO2 as an efficient agent to promote the synthesis of 2-arylbenzimidazole
from Schiff base has been demonstrated under mild conditions.
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone, a mild catalyst for the formation of carbon-nitrogen bonds
作者:Jean Jacques Vanden Eynde、Florence Delfosse、Pascal Lor、Yves Van Haverbeke
DOI:10.1016/0040-4020(95)00252-4
日期:1995.5
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) catalyzes the preparation of N-tetrahydropyranylbenzazoles, 2-substituted 1,3-diphenylimidazolidines, and N-(arylmethylene)benzene-1,2-diamines. In the latter case, use of one equivalent of DDQ provides a novel one-pot method for the synthesis of 1H-benzimidazoles.