Preparation of some chromeno[4,3-d]pyrido[1,2-a]pyrimidine derivatives by ultrasonic irradiation using NiFe2O4@SiO2 grafted di(3-propylsulfonic acid) nanoparticles

NiFe2O4@SiO2 grafted di(3-propylsulfonic acid) was prepared by a facile method and characterized using XRD, FT-IR, SEM-EDX, TGA, and BET techniques. The XRD pattern shows the characteristic peaks of the cubic structure for NiFe2O4. The presence of sulfonic acid groups was confirmed by FT-IR analysis. The catalyst was used for the preparation of chromeno[4,3-d]pyrido[1,2-a]pyrimidine derivatives via the three-component condensation reaction of 4-hydroxycoumarin, aldehydes, and 2-aminopyridines under US irradiation. The effects of solvent, temperature, and catalyst dosage on product formation under the reaction conditions were investigated. The simple procedure, good yields, short reaction times, and catalyst recovery are some of the key advantages of this method.