Benign and highly efficient synthesis of indenoquinoline derivatives from 3-arylamino-5,5-dimethylcyclohex-2-enone, arylaldehyde and 1,3-indenedione in ionic liquid medium

摘要

A green and simple syntheses of indeno[1,2-b]quinoline derivatives was accomplished in excellent yields via the reaction of 3-ary lamino-5,5-dimethylcyclohex-2-enone, aromatic aldehyde and 1,3-indenedione in ionic liquid medium of [bmim(+)][BF4-] as a green solvent. It was interesting that one of the protons exhibited doublet within 5.06 similar to 5.28 ppm identified as one of the aromatic protons from the indene ring. The reason was perhaps best explained by intramolecular C-H center dot center dot center dot pi stacking interaction, and confirmed by X-ray diffraction analysis in one case.