N1,N1,N2,N2-Tetramethyl-N1,N2-bis(sulfo)ethane-1,2-diaminium chloride as a highly efficient catalyst for synthesis of some nitrogen- and oxygen-containing heterocyclic compounds

In this research, a Brønsted acidic ionic liquid namely N1,N1,N2,N2-tetramethyl-N1,N2-bis(sulfo)ethane-1,2-diaminium chloride {[TMBSED][Cl]2} was employed as a highly efficient catalyst for the solvent-free production of some nitrogen- and oxygen-containing heterocyclic compounds including: (i) polyhydroquinolines (from arylaldehydes, dimedone, β-ketoesters and ammonium acetate), (ii) 3,4-dihydropyrimidin-2-(1H)-ones/thiones (from arylaldehydes, β-ketoesters and urea/thiourea), and (iii) 14-aryl-14H-dibenzo[a,j]xanthenes (from aromatic aldehydes and β-naphthol). In all cases, the heterocycles were obtained in high yields and in short reaction times. The salient features of using [TMBSED][Cl]2 in the reactions, include effectiveness, generality, simple preparation of the catalyst from inexpensive and easy available reactants, achieving the reactions under solvent-free conditions, synthesis of the products with high yields in short reaction times and need to milder conditions compared with many reported methods for the preparation of the aforesaid organic compounds.