SiO@Benzothiazole-Cl@Fc as an Efficient Heterogeneous Catalyst for the Synthesis of 1,3,5-Trisubstituted Pyrazoles by A Coupling.

This research introduces the preparation and analysis of a newly heterogeneous catalyst developed silica nanospheres supporting a ferrocene-containing ionic liquid (IL) (SiO@Benzothiazole-Cl@Fc) for the A3 coupling reaction. The catalyst facilitates the efficient synthesis of 1,3,5-trisubstituted pyrazoles from aromatic hydrazides, aldehydes, and aromatic alkynes. Incorporating ferrocene enhances the catalytic activity. Comprehensive characterization techniques, including NMR, Fourier transform infrared, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy, confirm the successful functionalization of silica nanospheres. The catalytic performance was evaluated under various reaction conditions, demonstrating high yields and selectivity for the desired pyrazole products. This work highlights the potential of ferrocene-based ILs in green chemistry applications, providing a sustainable approach to synthesizing valuable heterocyclic compounds.