Application of [Pyridine-1-SO3H-2-COOH]Cl as an efficient catalyst for the preparation of hexahyroquinolines

Pyridinium-1-sulfonic acid-2-carboxylic acid chloride {[Pyridine-1-SO3H-2-COOH]Cl} was synthesized and applied as a novel and efficient catalyst for the preparation of hexahydroquinolines by the one-pot multi-component condensation reaction of various aryl aldehydes with dimedone (5,5-dimethylcyclohexane-1,3-dione), β-ketoesters and ammonium acetate under mild and solvent-free conditions. Low cost, non toxic nature, simple work-up and excellent yields of products are the main advantages of this work.