Piperazine-grafted magnetic graphene oxide as a sustainable heterogeneous catalyst for solvent-free Biginelli reaction

Multi-component reactions (MCRs) are powerful tools for the one-pot synthesis of complex organic compounds, with the Biginelli reaction being one of the most important due to its versatility in synthesizing a wide range of dihydropyrimidine-2-ones (DHPMs) with diverse biological activities. However, traditional MCR catalysts are often homogeneous and challenging to recycle, leading to environmental concerns and high costs. In this study, we developed a novel heterogeneous catalyst for the Biginelli reaction by functionalizing graphene oxide (GO) with piperazine (NH) to form a Fe3O4@GO-NH nanocomposite. The catalyst was characterized using FT-IR, TGA, and SEM/EDX and showed high catalytic activity for the Biginelli reaction under solvent-free conditions. The optimal reaction conditions were determined by adjusting various parameters such as temperature, stability and reproducibility, time, and the molar percentage of Fe3O4@GO-NH. As a result of this eco-friendly approach, 32 Biginelli products were successfully obtained with high yields. The catalyst was also reusable, making it a more environmentally friendly and cost-effective alternative to conventional homogeneous catalysts.