This study reports a simple and facile route for the synthesis of ZnO nanoparticles (ZnO−NPs) decorated on reduced graphene oxide nanosheet (ZnO−NPs@r-GO) as a heterogeneous catalyst and tested over multicomponent one-pot A³-coupling reaction. The reduction of graphene oxide with the anchoring of ZnO−NPs on the r-GO nanosheet was observed through the X-ray diffraction patterns, Raman, FTIR, and XPS results of the ZnO−NPs@r-GO sample. ZnO−NPs (average particle size of 3.4±1.5 nm) with uniform size distribution over r-GO nanosheet were substantiated through HRTEM analysis. Impressively, ZnO−NPs@r-GO significantly used for A³-coupling reaction with different aromatic aldehydes, active methylene compounds, and urea and under the optimized reaction conditions gave exceptional activity to produce synthetically valuable 3,4-dihydropyrimidinones products (possessing diverse therapeutic and pharmacological properties) i. e. 97 % isolated yield of the product. In addition, excellent reusability up to 4 repeated cycles are the key advantages of the present catalyst used for this multicomponent A³-coupling reaction.

中文翻译：

---

嵌入还原氧化石墨烯纳米片 (ZnO−NPs@r-GO) 上的 ZnO 纳米颗粒作为单锅 A3 偶联反应的多相催化剂

本研究报告了一种简单易行的合成氧化石墨烯纳米片 (ZnO-NPs@r-GO) 上装饰的 ZnO 纳米粒子 (ZnO-NPs) 作为多相催化剂的途径，并通过多组分单锅 A ³偶联反应进行测试. 通过 ZnO-NPs@r-GO 样品的 X 射线衍射图、拉曼光谱、FTIR 和 XPS 结果，观察到氧化石墨烯的还原与 ZnO-NPs 在 r-GO 纳米片上的锚定。通过 HRTEM 分析证实了在 r-GO 纳米片上具有均匀尺寸分布的 ZnO-NPs（平均粒径为 3.4±1.5 nm）。令人印象深刻的是，ZnO−NPs@r-GO 显着用于 A ³-与不同的芳香醛、活性亚甲基化合物和尿素的偶联反应以及在优化的反应条件下产生了特殊的活性，以产生具有合成价值的 3,4-二氢嘧啶酮产品（具有多种治疗和药理特性） i. e. 产物的分离产率为 97%。此外，用于这种多组分 A ³偶联反应的本催化剂的主要优点是高达 4 次重复循环的出色重复使用性。