One-pot multicomponent synthesis of unsymmetrical polyhydroquinoline derivatives with 1,1′-butylenebispyridinium hydrogen sulfate as an efficient, halogen-free and reusable Brönsted ionic liquid catalyst

1,1′-Butylenebispyridinium hydrogen sulfate is an efficient, halogen-free and reusable Brönsted ionic liquid catalyst for the synthesis of ethyl-4-aryl/heteryl-hexahydro-trimehtyl-5-oxoquinoline-3-carboxylates by the one-pot condensation of dimedone, aryl/heteryl aldehydes, ethyl acetoacetate, and ammonium acetate under solvent-free conditions. This method has the advantages of high yield, clean reaction, simple methodology, and short reaction time. The ionic liquid can be recycled five times without significant loss of the catalytic activity.

Graphical AbstractEthyl-4-aryl/heteryl-hexahydro-trimehtyl-5-oxoquinoline-3-carboxylates were synthesized by the one-pot condensation of dimedone, aryl/heteryl aldehydes, ethyl acetoacetate, and ammonium acetate with 1,1′-butylenebispyridinium hydrogen sulfate (Bbpy)(HSO4)2 as an efficient, halogen-free, and reusable Brönsted ionic liquid catalyst under solvent-free conditions. High yield, clean reaction, simple methodology, short reaction time, and recyclability of the ionic liquid are the advantages of the method.Figure optionsDownload as PowerPoint slide