Ultrasound-assisted green synthesis of bis(indolyl)methanes catalyzed by acidic Ionic liquid (CH_2)4SO_4HMIM HSO_4

摘要

The acid ionic liquid l-methyl-3-(4-sulfobutyl)-1H-imidazolium bisulfate [(CH_2)4SO_4HMIM] [HSO_4] was an efficient catalyst for the electrophilic substitution of indole with carbonyl compounds to afford the corresponding bis(indolyl)methanes in good yields under ultrasound irradiation. Notable features of this new procedure are shorter reaction times, cleaner reaction profiles, simple experimental and efficient recovery and recycling of the ionic liquid.