Application of new multi-H-bond catalyst for the preparation of substituted pyridines via a cooperative vinylogous anomeric-based oxidation

A new pseudopolymeric nanomagnetic catalyst containing urea linkers, namely Fe3O4@SiO2@[(CH2)(3)-urea-(CH2)(2)-O-(CH2)](2), was synthesized. The mentioned nanomagnetic catalyst was characterized by using several methods including Fourier transform infrared spectroscopy, thermogravimetric/differential thermogravimetric analysis, vibrating sample magnetometer analysis, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray analysis. In this research, we examined the catalytic usage of Fe3O4@SiO2@[(CH2)(3)-urea-(CH2)(2)-O-(CH2)](2) for the preparation of a wide range of 2-amino-3-cyano and 2-hydroxy-3-cyanopyridine derivatives bearing thiophene or furan moieties. All desired hybrid pyridines were synthesized in short reaction times with high yields. The crucial finding is that the catalyst was very efficient, stable, and easy retrieve. In addition, a vinylogous anomeric-based oxidation pathway is suggested as a mechanism for the preparation of target molecules.