Brønsted acidic ionic liquid based magnetic nanoparticles: a new promoter for the Biginelli synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones

The Brønsted acidic ionic liquid 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium hydrogen sulfate was immobilized on magnetic Fe3O4 nanoparticles (MNPs-IL-HSO4). The properties of the magnetic nanocatalyst were characterized by FT-IR, EDX, SEM, elemental analysis, XRD, VSM, and TGA. The results showed that the ionic liquid had been successfully immobilized onto the magnetic support, and the immobilized ionic liquid catalysts exhibited high catalytic activity in the Biginelli reaction under mild conditions for the synthesis of a diverse range of 3,4-dihydropyrimidin-2(1H)-ones. It also maintained satisfactory catalytic activity for the synthesis of Biginelli compounds after 8 rounds of recycling. The separation and reuse of the novel solid catalyst were simple, effective and economical.