Novel Brønsted Acidic Ionic Liquids Based on Benzimidazolium Cation: Synthesis and Catalyzed Conjugate Addition of Indoles with α,β-unsaturated Ketones
Brønsted acidic ionic liquids based on benzimidazolium cation was synthesized and employed as an efficient catalysts for the Michael addition reaction of indoles to α,β-unsaturated ketones under mild conditions to afford the corresponding conjugate addition products in high yields (90%-98%). The catalyst 1-butyl-3-(3-sulfopropyl)benzimidazolium p-toluenesulfonate ([PSbbim][p-CH3PhSO3]) could be reused at least three times without a noticeably decrease in its activity.
Zhong Cao, Lixian Sun, Xueqiang Cao, Yinghe He
B. Wang and C. J. Liu, "Novel Brønsted Acidic Ionic Liquids Based on Benzimidazolium Cation: Synthesis and Catalyzed Conjugate Addition of Indoles with α,β-unsaturated Ketones", Advanced Materials Research, Vols. 233-235, pp. 977-984, 2011