FeF3 as a novel catalyst for the synthesis of polyhydroquinoline derivatives via unsymmetrical Hantzsch reaction

A facile and highly efficient one-pot synthesis of polyhydroquinoline derivatives is reported via four-component condensation reaction of aldehydes, β-keto compounds, active methylene compounds and ammonium acetate in the presence of FeF3 as a catalyst in ethanol at 75–80 °C. The method offers several advantages including high yields, short reaction time, simple work-up procedure and catalyst reusability for several runs. The higher catalytic activity of FeF3 ascribed due to its high acidity, thermal stability and water tolerance. The superiority of use of FeF3 to the current process is compared with other Lewis acids, Fe-salts, fluoride sources and insights of the origin of the efficiency are discussed.