Isonicotinic acid as an efficient catalyst for the synthesis of hexahydroquinolines

Quinolines with a 1,4-dihydropyridine structure are promising scaffolds due to their pharmacological activities. This part of quinoline derivatives has very utilizations inmedicinal chemistry and applied as antiasthamatic, anti-inflammatory, antimalarial, antibacterial, antihypertensive, and tyrosine kinase inhibiting compounds [1-3]. Oneof the important classes of DHPs with a modified structural scaffold is hexahydroquinolines (HHQs) which could be synthesized by the reaction of various aromatic aldehydes, dimedone, β-ketoesters and ammonium acetate using different catalysts. Herein, we have reported the preparation of hexahydroquinolines using isonicotinic acid, at 60 °C under solvent-free conditions (Scheme 1).