N1,N1,N2,N2-tetramethyl-N1,N2-bis(sulfo)ethane-1,2-diaminium Chloride ([TMBSED][Cl]2): An Efficient Ionic Liquid Catalyst for the One-pot Synthesis of Dihydropyrrol-2-ones and Tetrahydropyridines

N1,N1,N2,N2-tetramethyl-N1,N2-bis(sulfo)ethane-1,2-diaminium chloride ([TMBSED][Cl]2) was synthesized as an acidic ionic liquid and characterized using FT-IR, 1H and 13C NMR, mass spectroscopy, TG, DTG and DTA techniques. This ionic liquid was employed as efficient catalyst for the extremely facile and efficient synthesis of dihydropyrrol-2-ones and functionalized tetrahydropyridines. One-pot four-component reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in the presence of [TMBSED][Cl]2 in ethanol at ambient temperature provides substituted dihydropyrrol-2-ones in good to high yields. This ionic liquid catalyst was also found useful for the synthesis of functionalized tetrahydropyridines using a multi-component reaction of amines, aldehydes and β-ketoesters in methanol.