Fe3O4@nano-cellulose/TiCl as an efficient and magnetically nanocatalyst for the synthesis of indenopyrido[2,3-d]pyrimidine derivatives

Magnetic core-shell nanoparticles, Fe3O4@nano-cellulose, are prepared through in situ co-precipitation of Fe3+ and Fe2+ ions via NH4OH in an aqueous solution of nanocellulose [1-2]. Treatment of Fe3O4@nanocellulose with TiCl4 leads to the formation of Fe3O4@nano-cellulose/TiCl as a novel recyclable catalyst. This catalyst wascharacterized by FT-IR, FESEM, TEM, XRF, VSM, EDX and XRD. Pyridopyrimidines are nitrogen-bearing heterocyclic compounds which have various pharmaceutical applications. In particular, pyrido[2,3-d]pyrimidine derivatives show variable biological activities such as anticancer agents inhibiting dihydrofolate reductases, antiviral, antihistaminic and anti-inflammatory [3]. In this research, the synthesis of indenopyrido [2,3-d] pyrimidine derivatives has developed via a three component reaction of aldehyde, 1,3- indanedione and 6-amino-2-(methylthio) pyrimidin-4(3H)-one using Fe3O4@nano-cellulose/TiCl in ethanol at 60°C (Scheme 1). After completion of the reaction, the catalyst was separated by an external magnet and reused for the next experiment. For more purification of product, solid was recrystallized by ethanol. Several advantages of thisprotocol are good yields, environmentally benign, easy work-up and moderate reusability of the catalyst. The structures of the products were confirmed by elemental analyses, IR, 1H, and 13C NMR spectra