New Crown Ether-Based Nano Ionic Liquid ([DB-18-C-6K+][OH-] nIL): A Versatile Nanocatalyst for the Synthesis of Spiro[indoline-3,2'-quinoline] Derivatives via the Cascade Four-Component Reaction of Arylamines, Dialkylacetylenedicarboxylates, Isatins and Dimedone

A new nano-size crown ether-based ionic liquid on the basis of dibenzo-18-crown-6 ([DB-18-C-6K(+)][OH-] nIL) has been synthesized via a simple procedure and characterized through fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, high-resolution scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric/differential thermal analysis, and UV-Vis spectroscopy techniques The obtained catalyst has been utilized for the one-pot, four-component synthesis of spiro[indoline-3,2'-quinoline] derivatives from the combination of isatins, amines, dimedone, and dialkylacetylenedicarboxylates. The advantages of this protocol included the use of common and easily-available starting materials, utilizing ambient temperature, non-toxic and inexpensive reagent usage, high yields of products, and operationally simple procedure. [GRAPHICS] .