An efficient strategy for N-alkylation of benzimidazoles/imidazoles in SDS-aqueous basic medium and N-alkylation induced ring opening of benzimidazoles
作者:Ankita Chakraborty、Sudipto Debnath、Tanmoy Ghosh、Dilip K. Maiti、Swapan Majumdar
DOI:10.1016/j.tet.2018.08.029
日期:2018.10
alkyl halides reaction proceeds at ambient temperature whereas in the cases of less reactive alkyl halides require 55–60 °C to complete alkylation process. N-alkylation induced ring opening of the heterocyclicring in benzimidazole derivatives to multifunctional aromaticcompounds were noticed at 60 °C when more than two equivalents of alkyl halide was used.
A novel protocol for nickel-catalyzed direct sp2 CâH bond alkylation of N-aromatic heterocycles has been developed. This new reaction proceeded efficiently at room temperature using a Grignard reagent as the coupling partner. This approach provides new access to a variety of alkylated N-aromatic heterocycles which are potentially of great importance in medicinal chemistry.
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])