Design, Characterization and Application of N1,N1,N2,N2-Tetramethyl-N1,N2-bis(sulfo)ethane-1,2-diaminium Trifluoroacetate as a Novel Ionic-Liquid Catalyst for the Production of Polyhydroquinolines

A novel Brønsted acidic ionic liquid namely N1,N1,N2,N2-tetramethyl-N1,N2-bis(sulfo)ethane-1,2- diaminium trifluoroacetate {[TMBSED][TFA]2} was synthesized, and characterized by studying its 1H NMR, 13C NMR, 19F NMR and mass spectral data. Afterward, the ionic liquid was applied as catalyst for the production of polyhydroquinoline derivatives via the one-pot multi-component reaction of arylaldehydes with dimedone, β-ketoesters and ammonium acetate under solvent-free conditions. The protocol had several advantages, which include: (i) efficiency, (ii) generality, (iii) excellent yields of the products, (iv) short reaction times, (v) clean reaction profile, (vi) simplicity, (vii) usage of a few amount of the catalyst, (viii) easy preparation the catalyst from available and inexpensive starting materials, (ix) mild reaction conditions, (x) performing the reaction in solventfree conditions, and (xi) easy work-up.