Efficient synthesis of novel pyranoquinoline derivatives from simple acetanilide derivatives: experimental and theoretical study of their physicochemical properties using DFT calculations

A convenient reaction of 2-chloroquinoline-3-carbaldehyde derivatives and dimedone in the presence of KF-Al2O3 for the synthesis of useful pyranoquinolines is described. Reasonable yields (41-50%), easily available starting materials and less expensive efficient catalyst are the key features of the present method. A mechanism was proposed for the reaction course. Attribution of the chemical shifts was made with the help of the density functional theory (DFT) calculations. The computed nuclear magnetic resonance (NMR) chemical shifts are in good agreement with available experimental data. The nucleus-independent chemical shift (NICS) values were used as quantitative measures for the relative aromatic character in pyranoquinolines. The calculated NICS values obtained for the phenyl group of pyranoquinoline compounds are smaller than that of benzene.

quinoline; pyranoquinoline; Knoevenagel condensation; aromaticity; DFT calculations