Magnetic based piconaldehyde-melamine copper complex for the one-pot synthesis of hexahydroquinolines via Hantzsch four component reactions

In the present work, piconaldehyde-melamine copper complex was loaded on the magnetic Fe3O4 core, so that it contains 0.33 mmol Cu per g of the catalyst and usedas an efficient catalyst. The catalyst was used to motivate the raw materials in the synthesis of hexahydroquinoline derivatives by the one-pot four component reaction.Reaction between various aryl aldehydes, dimedone, ethyl acetoacetate and ammonium acetate was carried out at the optimum condition. Different aryl aldehyde derivatives with electron withdrawing and electron donating groups on the benzene ring were successfully examined.Low reaction time (minutes vs. half an hour),solvent free condition, and magnetically separable catalyst are some salient features of the developed catalyst. Besides, the optimum amount of the catalyst and temperature was obtained 0.07 g, and 87.6 ○C, respectively, which was determined using response surface methodology (RSM) and optimization techniques. The proposed and plausible mechanism based on FT-IR is shown in the Fig. 1. As it shown (Fig. 1), and based on the FT-IR investigations, the as prepared catalyst interacts only with benzaldehyde and reduces the carbonyl wave number from 1703.92 cm-1 to 1687.49 cm-1.