Synthesis of Acridinediones and Biscoumarins Using Fe3O4@SiO2@Ni-Zn-Fe LDH as an Efficient Magnetically Recoverable Mesoporous Catalyst

An efficient green method has been developed for the cascade multi-component Hantzsch reaction of acridinediones and biscoumarins using Fe3O4@SiO2@Ni-Zn-Fe layered double hydroxide (LDH). Nano Ni-Zn-Fe LDH immobilized on silica-layered magnetite was synthesized via a simple co-precipitation procedure, and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The nanocatalyst has the usual features of Fe3O4@SiO2 and Ni-Zn-Fe LDH. Moreover, it contains magnetism properties which is related to the presence of magnetite in the nanocatalyst and can be easily separated from the reaction mixture with an external magnetic field. Subsequently, the nanomagnetic-LDH was used to evaluate catalytic activity with the tandem synthesis of acridinedione and biscoumarin derivatives. The mesoporous catalyst showed excellent performance for multi-component reactions between aromatic aldehydes, 4-hydroxycoumarin, and dimedone and ammonium acetate. Acridinediones were provided within 15-35 min in 80-96% yields under solvent-free conditions in 70-80 degrees C and also, biscoumarins were obtained within 1-40 min in 87-95% yields under reflux conditions in water. The present study includes noteworthy advantages of mild reaction conditions, short times of reaction, absence of hazardous and expensive organic solvents and reagents, presence of water as an eco-friendly solvent, using green nanomagnetic-LDH and the ability to recycle the nanocatalyst.

Automated summary

An efficient green method using Fe3O4@SiO2@Ni-Zn-Fe layered double hydroxide was developed for the multi-component Hantzsch reaction. The nanocatalyst, with magnetism properties and the ability to be easily separated from the reaction mixture, showed excellent performance for the cascade synthesis of acridinediones and biscoumarins. Significant advantages include mild reaction conditions, short reaction times, absence of hazardous organic solvents, and the ability to recycle the nanocatalyst.