In this paper, a magnetic nanocatalyst of Fe₃O₄@SiO₂-ZnCl₂ has been used which enhances the synthesis of benzimidazoles, coumarins, benzoxazines and dihydropyrimidinones. To begin with, 2-substituted benzimidazoles have been synthesized in proper to high yields from 1,2-phenylenediamine with extensive diversity of aromatic aldehydes in the presence of magnetic nanocatalyst. Then, this magnetic nanocatalyst has been used for the synthesis of coumarin derivatives via Pechmann condensation reaction of phenols with ethyl acetoacetate in good yield under solvent-free conditions. Next, the synthesis of benzo[b][1,4]oxazines has been accomplished efficiently by the multi-component condensation of 2-aminophenol, aromatic aldehyde and isocyanide using magnetic nanocatalyst. Lastly, dihydropyrimidinones were synthesized by a one-pot three-component cyclocondensation using β-keto ester, substituted aromatic aldehyde and urea. The benefits of this method are facile, easy work-up, catalyst reusability and leading to good yields. Theoretical assessments allow us to corroborate the reactions mechanism.

本文研究了Fe ₃ O ₄ @SiO ₂ -ZnCl ₂的磁性纳米催化剂。已使用可增强苯并咪唑，香豆素，苯并恶嗪和二氢嘧啶酮的合成的化合物。首先，在磁性纳米催化剂的存在下，由1,2-苯二胺以适当的产率高收率合成了2-取代的苯并咪唑，其中芳香族醛种类繁多。然后，该磁性纳米催化剂已用于在无溶剂条件下通过苯酚与乙酰乙酸乙酯的Pechmann缩合反应以良好的收率合成香豆素衍生物。接下来，使用磁性纳米催化剂通过2-氨基苯酚，芳族醛和异氰酸酯的多组分缩合有效地完成了苯并[b] [1,4]恶嗪的合成。最后，使用β-酮酯通过一锅三组分环缩合反应合成二氢嘧啶酮，取代的芳香醛和尿素。该方法的优点是易于操作，易于后处理，催化剂可重复使用，并具有良好的收率。理论评估使我们能够证实反应机理。