Background: In recent years, ionic liquids (ILs) were used as solvents due to their particular properties, such as the ability to dissolve many organic and inorganic substances and undetectable vapour pressure [1]. Polyhydroquinolines are possessed biological and physiological activities such as calcium channel blockers, hepatoprotective, bronchodilator, anti tumor, antidiabetic activity, etc [2]. Recently, the synthesis of polyhydroquinolines has been achieved in the presence of various catalysts, such as L-proline [3] and ZrCl4 [4].
Methods: A mixture of benzaldehyde (1mmol), ethyl acetoacetate (1mmol), dimedone (1mmol), ammonium acetate (1 mmol) in ethanol (3 mL) containing catalytic amount of ionic liquid was stirred at room temperature and the reaction was followed by TLC. After completion of the reaction the pure product was crystallized from ethanol.
Results: Herein, we reported an efficient method for the synthesis of some polyhydroquinolines via a four-component condensation reaction between dimedone, ethyl acetoacetate, aromatic aldehydes, and ammonium acetate in the presence of catalytic amounts of dicationic ionic liquid (DiEG(mim)2[Br]2) in ethanol at room temperature. This method tolerate with various aromatic aldehydes bearing electron-donating or electron-withdrawing groups in short reaction times and high yields