Hassanzadeh-Afruzi Fereshte, Amiri-Khamakani Zeinab, Saeidirad Mahdi, Salehi Mohammad Mehdi, Taheri-Ledari Reza, Maleki Ali
Catalysts and Organic Synthesis Research Laboratory, Department of Chemistry, Iran University of Science and Technology Tehran 16846-13114 Iran
RSC Adv. 2023 Apr 3;13(15):10367-10378. doi: 10.1039/d2ra07228a. eCollection 2023 Mar 27.
Pyrazolopyridines are common scaffolds in various bioactive compounds, which have several therapeutic effects and unique pharmacological properties. In this study, we fabricated a novel environmentally friendly silica-based nanocomposite as a multifunctional catalytic system for the synthesis of pyrazolopyridine derivatives. This novel heterogeneous nanocomposite named Alg@SBA-15/FeO (Alg stands for alginic acid), was prepared in several steps. In this regard, SBA-15 was synthesized by the hydrothermal method. Next, it was magnetized by FeO nanoparticles an co-precipitation process. Then, SBA-15/FeO particles were functionalized with 3-minopropyltriethoxysilane (APTES). Afterward, Alg@SBA-15/FeO was obtained by a nucleophilic substitution reaction between SBA-15/FeO-NH and an as-synthesized methyl-esterified alginic. Different analyses such as Fourier-transform infrared (FTIR), energy-dispersive X-ray (EDX) spectroscopy, field-emission scanning-electron microscopy (FESEM), vibrating-sample magnetometer (VSM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and BET (Brunauer-Emmett-Teller) have been used to confirm the structure of the fabricated catalyst. The magnetic properties of the Alg@SBA-15/FeO catalytic system imparted by FeO MNPs enable it to be conveniently isolated from the reaction mixture by using an external magnet. According to the obtained results, the prepared nanocatalyst has high thermal stability and it lost approximately 26% of its weight up to 800 °C. Interestingly, a small amount of prepared nanocatalyst (0.02 g) has shown excellent catalytic performance in the synthesis of pyrazolopyridine derivatives (90-97%) in a short reaction time (20-30 min) at room temperature which can be attributed to its porous structure and large surface area, and the presence of many acidic and basic functional groups. In general, it can be argued that the Alg@SBA-15/FeO nanocomposite deserves more attention due to its non-toxicity, ease of preparation, good recyclability, and its high catalytic efficiency.
吡唑并吡啶是各种生物活性化合物中的常见骨架，具有多种治疗作用和独特的药理特性。在本研究中，我们制备了一种新型的环境友好型二氧化硅基纳米复合材料，作为合成吡唑并吡啶衍生物的多功能催化体系。这种新型的多相纳米复合材料名为Alg@SBA-15/FeO（Alg代表海藻酸），通过几个步骤制备而成。在这方面，SBA-15通过水热法合成。接下来，通过FeO纳米颗粒在共沉淀过程中将其磁化。然后，用3-氨丙基三乙氧基硅烷（APTES）对SBA-15/FeO颗粒进行功能化。之后，通过SBA-15/FeO-NH与合成的甲基酯化海藻酸之间的亲核取代反应得到Alg@SBA-15/FeO。采用傅里叶变换红外光谱（FTIR）、能量色散X射线光谱（EDX）、场发射扫描电子显微镜（FESEM）、振动样品磁强计（VSM）、X射线衍射（XRD）、热重分析（TGA）和BET（布鲁诺尔-埃米特-泰勒）等不同分析方法来确认所制备催化剂的结构。由FeO MNPs赋予的Alg@SBA-15/FeO催化体系的磁性使其能够通过使用外部磁铁方便地从反应混合物中分离出来。根据所得结果，所制备的纳米催化剂具有高热稳定性，在高达800°C时其重量损失约26%。有趣的是，少量制备的纳米催化剂（0.02 g）在室温下短反应时间（20 - 30分钟）内合成吡唑并吡啶衍生物时表现出优异的催化性能（90 - 97%），这可归因于其多孔结构和大表面积以及存在许多酸性和碱性官能团。总体而言，可以认为Alg@SBA-15/FeO纳米复合材料因其无毒、易于制备、良好的可回收性和高催化效率而值得更多关注。
