1,4-Diazabicyclo[2.2.2]octanium Diacetate under Grinding: Efficient and Eco-Friendly Process for the Synthesis of Symmetric, Unsymmetric and New Bis di(indolyl)indolin-2-one

Background: A facile, effective, new and green methodology has been developed for the synthesis of 3,3-di(indolyl)indolin-2-one through electrophilic condensation reaction of indole derivatives with various isatins in the presence of 1,4-diazabicyclo[2.2.2]octanium diacetate as an efficient homogeneous media under grinding. This work consistently has advantages as excellent yields, short reaction time, mild condition and simple work-up procedures. The catalyst could be easily recovered and reused for six cycles with almost consistent activity. All of the synthesized compounds were characterized by their physical constant, comparison with authentic samples, IR, 1H NMR, 13C NMR spectroscopy and elemental analysis. Keywords: Solvent free, 3, 3-di(indolyl)indolin-2-one, 1, 4-diazabicyclo [2.2.2] octanium diacetate, isatin, DABCO, symmetric.