Fe3O4@TiO2@O2PO2(CH2)NHSO3H as a novel nanomagnetic catalyst: Application to the preparation of 2-amino-4,6-diphenylnicotinonitriles via anomeric-based oxidation

A new, green and reusable nanomagnetic heterogeneous catalyst, namely Fe3O4@TiO2@O2PO2(CH2)NHSO3H, was synthesized and fully characterized using suitable techniques such as infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopies, thermogravimetry, vibrating sample magnetometry and energy-dispersive X-ray spectroscopy. The applicability of the constructed heterogeneous core-shell catalyst as a promoter was successfully explored for the synthesis of 2-amino-4,6-diphenylnicotinonitrile derivatives upon the reaction of a good range of aromatic aldehydes, acetophenone derivatives, malononitrile and ammonium acetate. The desired products were obtained with good to high yields in short reaction times under solvent-free conditions. The suggested mechanism offers an anomeric-based oxidation route to the products in the final step of the synthetic pathway.