One-pot synthesis of 2-amino-4H-chromene derivatives catalysed by Fe3O4@SiO2@Mg-Al-LDH as an efficient and reusable magnetic nano- catalysts

This work describes the environmentally friendly preparation of Fe3O4 utilizing agro-waste orange peel ash aqueous extract as a solvent medium, and then it functionalized to SiO2@Mg-Al-LDH under ultrasonication. Further, these prepared materials were characterized by FT-IR, XRD, FE-SEM, EDX, and VSM. Furthermore, it demonstrated the application of this functionalized iron oxide for the synthesis of 2-amino-4H-chromene derivatives. The synthesis routed via a one-pot three-component reaction (3CRs) of aryl/heterocyclic aldehyde, malononitrile, and resorcinol under MWI at 180W using EtOH as a solvent gave excellent product isolation achieved in a short reaction time. The catalyst is very efficient towards both electron-withdrawing and electron-donating groups present on aryl or heterocyclic aldehydes. The magnetic nature of this catalyst allows it to be easily separated by a permanent magnetic field, and catalysts can be reused several times without losing significant catalytic activity. Additionally, selected synthesized chromene derivatives were tested for their antimicrobial properties using agar media. The compounds 4b, 4c, and 4d showed comparable activity tested against bacteria and fungi. Research Highlights • Biogenic synthesis of Fe3O4, and its surface modified was performed. • Heterogeneous catalysts (Fe3O4@SiO2@Mg-Al-LDH) was prepared and characterized. • The pointed catalyst was applied in the synthesis of chromene derivative. • Antimicrobial activity of synthesized compounds were studied.