Background: A wide variety of dihydropyrimidins (DHPMs) exhibit pharmacological and biological activities. Herein, an efficient one-pot synthesis of some 3, 4-dihydropyrimidin-2(1H)-one derivatives is reported using Fe3O4 @SiO2–Pr-INH.

Objective: Recently, several catalysts have been used to improve the Biginellis-reaction. However, some of these catalysts have imperfections. Herein, a convenient method for the synthesis of 3, 4-dihydropyrimidin- 2(1H)-ones and their sulfur derivatives using Fe3O4 @SiO2–Pr-INH is reported.

Materials and Methods: Firstly, the catalyst was synthesized through a simple four-step method. The Fe3O4 MNPs were synthesized using the chemical co-precipitation method, coated with a layer of silica using TEOS, and then functionalized with CPTMS. Subsequently, a nucleophilic substitution of Cl by isoniazid resulted in the formation of the magnetic Fe3O4@SiO2–Pr-INH. After the preparation and characterization of Fe3O4@SiO2–Pr-INH, its catalytic activity was studied in the synthesis of 3, 4-dihydropyrimidin-2(1H)-one derivatives. Following the optimization of the reaction conditions, several 3, 4-dihydropyrimidin-2(1H)-one derivatives were synthesized by the reaction of ethyl acetoacetate or acetylacetone, thiourea or urea and aromatic aldehydes at 80 °C under solvent-free conditions.

Results: Isoniazid-functionalized Fe3O4 magnetic nanoparticles (Fe3O4@SiO2–Pr-INH) were prepared using Fe3O4 with silica layer and their surface was modified with isoniazid. They were characterized successfully by infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and were used for the synthesis of some 3, 4-dihydropyrimidin-2(1H)-one derivatives as catalysts. Aromatic aldehydes with electron-donating or electron-withdrawing groups afforded 3, 4- dihydropyrimidin-2(1H)-ones and their sulfur derivatives in good to excellent yields in short reaction times.

Conclusion: Isoniazid-functionalized Fe3O4 magnetic nanoparticles (Fe3O4@SiO2–Pr-INH) were used as an efficient catalyst for Biginelli-type synthesis of 3, 4-dihydropyrimidin-2(1H)-ones and 3, 4-dihydropyrimidin- 2(1H)-thiones in good to excellent yields and short reaction times. It is noteworthy that this method has several advantages such as simple experimental procedures, the absence of solvent, environmentally benign process, stability and reusability of the catalyst.

背景：多种二氢嘧啶（DHPM）表现出药理和生物学活性。在此，据报道使用Fe3O4 @ SiO2-Pr-INH可以有效地一锅合成一些3，4-dihydropyrimidin-2（1H）-one衍生物。

目的：最近，几种催化剂已用于改善Biginellis反应。然而，这些催化剂中的一些具有缺陷。本文报道了使用Fe3O4 @ SiO2-Pr-INH合成3，4-二氢嘧啶-2（1H）-及其硫衍生物的简便方法。

材料与方法：首先，通过简单的四步法合成催化剂。用化学共沉淀法合成Fe3O4 MNPs，用TEOS涂覆二氧化硅层，然后用CPTMS功能化。随后，异烟肼对Cl进行亲核取代，导致形成磁性Fe3O4 @ SiO2-Pr-INH。在Fe3O4 @ SiO2-Pr-INH的制备和表征后，在合成3，4-二氢嘧啶-2（1H）-一衍生物中研究了其催化活性。在优化反应条件之后，在无溶剂条件下，通过使乙酰乙酸乙酯或乙酰丙酮，硫脲或脲与芳族醛在80°C下反应，合成了几种3，4-二氢嘧啶-2（1H）-一衍生物。

结果：使用具有二氧化硅层的Fe3O4制备了异烟肼官能化的Fe3O4磁性纳米粒子（Fe3O4 @ SiO2–Pr-INH），并对其表面进行了异烟肼改性。通过红外光谱，粉末X射线衍射，扫描电子显微镜，能量色散X射线光谱对它们进行了成功表征，并用于合成一些3，4-二氢嘧啶-2（1H）-one衍生物作为催化剂。具有给电子或吸电子基团的芳族醛在短的反应时间内以良好或优异的产率提供了3，4-二氢嘧啶-2（1H）-及其硫衍生物。

结论：异烟肼官能化的Fe3O4磁性纳米粒子（Fe3O4 @ SiO2–Pr-INH）被用作Biginelli型合成3，4-二氢嘧啶-2（1H）-one和3，4-二氢嘧啶-2（ 1H）-硫酮收率好至极好，反应时间短。值得注意的是，该方法具有许多优点，例如简单的实验程序，无溶剂，对环境无害的方法，催化剂的稳定性和可重复使用性。