Novel SO3H‐Functionalized Ionic Liquids Catalyzed a Simple, Green and Efficient Procedure for Fischer Indole Synthesis in Water under Microwave Irradiation.

Abstract Novel SO 3 H-functionalized ionic liquids were successfully applied as catalysts for one-pot Fischer indole synthesis under microwave irradiation and in a water medium. Various types of indoles were prepared using single-carbonyl ketones/aldehydes or cyclohexandiones with aryhydrazine hydrochlorides in 86–96% yields in water under microwave irradiation. The indole products could be conveniently separated from the reaction mixture through filtration, and the catalytic system of [(HSO 3 -p) 2 im][CF 3 SO 3 ]/H 2 O could be reused directly without any treatment. The entire process is simple, time saving, and environmentally friendly.