Nano-Ticl4.SiO2: a Versatile and Efficient Catalyst for Synthesis of Dihydropyrimidones via Biginelli Condensation

Abstract

Nano-TiCl₄.SiO₂ has been found to be an extremely efficient catalyst for the preparation of 3,4-dihydropyrimidinones/thiones via three-component reactions of an aldehyde, β-ketoester or β-diketone and urea or thiourea under mild conditions. Nano-TiCl₄.SiO₂ as a solid Lewis acid has been synthesized by reaction of nano-SiO₂ and TiCl₄. The structural characterization of this acid has been studied by FT-IR (ATR), XRD, SEM and TEM. This process was simple and environmentally benign with high to excellent yields. Furthermore, the catalyst could be recovered conveniently and reused for at least three times.

KEYWORDS: Nano-TiCl₄.SiO₂, heterogeneous catalyst, multi-component reaction, β-ketoester, β-diketone, urea.