Multicomponent synthesis of new curcumin-based pyrano[2,3-d]pyrimidine derivatives using a nano-magnetic solid acid catalyst

Abstract

A new magnetic reusable nanocatalyst was developed via the chemical modification of magnetic nanoparticles (MNPs) surface with sulfanilic acid. The sulfanilic acid moieties on the surface of MNPs act as acidic catalytic sites for catalysis. This catalyst system was synthesized in a four-step process including preparation of core–shell MNPs (Fe₃O₄@SiO₂), reaction of MNPs with trimethoxy vinyl silane for the synthesis of vinyl-functionalized magnetic nanoparticles (VMNP), conversion of vinyl groups to oxirane rings (MNPO) and reaction of sulfanilic acid with MNPO. The MNP-SAA catalyst was characterized using different techniques including FT-IR, EDX, TEM, VSM, SEM, TGA, XRD, XPS, and elemental analysis. The DLS analysis and TEM images demonstrate that catalyst nanoparticles have an average size of 14 nm, which is suitable for catalysis. The amount of acidic sites on a catalyst surface is suggested to be about 1.65 mmol g⁻¹. The catalyst was used in a multicomponent reaction between curcumin, barbituric acids and aldehydes for efficient synthesis of a class of curcumin-based pyrano[2,3-d]pyrimidine derivatives in good to excellent yields.