Tetrazoles are an important class of heterocycles combining high nitrogen content with significant biological properties. Among these are activities as sedatives, antibacterials, anticancer drugs, antidiabetic medications, antifungals, anti-inflammatories, general antimicrobials, antitumor compounds, antivirals, carboxylic acid isosteres, diuretics and herbicides. In continuation of our previous work on the application of magnetic nanoparticle metal complexes as heterogeneous catalysts for the synthesis of heterocyclic compounds, we would now like to report the preparation of the novel title Cu nano-catalyst. Our motivation was to promote a new efficient nano-catalyst for greener methods and potentially lower costs for the synthesis of heterocycles. The catalyst preparation occurred via a multistep process including: the synthesis of the Fe3O4 magnetic nanoparticles, coating the latter with tetraethyl orthosilicate (TEOS) (Fe3O4/SiO2), functionalization of Fe3O4/SiO2 with 3-chloropropyltrimethoxysilane (CPTMS) and 3-mercapto1,2,4-triazole (MT) ligands (Fe3O4/SiO2/CPTMS/MT), and further complexation with CuCl2 (Fe3O4/SiO2/CPTMS/MT/Cu). In a demonstration of its utility for diversity in synthesis, the new Cu magnetic nano-catalyst was subsequently used for the synthesis of a variety of useful tetrazoles from the reaction of amino acids with sodium azide and triethyl orthoformate (TEOF) in H2O at 40 C (Scheme 1). To the best of our knowledge, this is the first such application. The catalyst activity was optimized in a model reaction. This was the synthesis of 3-(1H-indol-3-yl)-2-(1H-tetrazol-1-yl)propanoic acid (2c) from the reaction of tryptophan with sodium azide and TEOF. The model was run under different conditions of temperature, amount of the catalyst and solvents. The best result was obtained with 10mmole of amino acid, 10mmole of sodium azide, 30mmole of TEOF and 20mg of the Cu nano-particle catalyst in H2O at 407 C (Tables 1-3). Applying the optimized results from the model, a number of tetrazoles were prepared with good to excellent yields (Table 4). All of the compounds were fully characterized (see Experimental section).

中文翻译：

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3-巯基-1,2,4-三唑官能化 Fe3O4 基铜纳米颗粒：一种用于从氨基酸合成多种四唑的有效催化剂

四唑是一类重要的杂环，结合了高氮含量和显着的生物学特性。其中包括镇静剂、抗菌剂、抗癌药物、抗糖尿病药物、抗真菌剂、抗炎剂、一般抗微生物剂、抗肿瘤化合物、抗病毒剂、羧酸等排体、利尿剂和除草剂的活性。继续我们之前关于磁性纳米颗粒金属配合物作为多相催化剂合成杂环化合物的应用，我们现在想报告新标题铜纳米催化剂的制备。我们的动机是为更环保的方法推广一种新的高效纳米催化剂，并可能降低杂环合成的成本。催化剂的制备是通过多步过程进行的，包括：Fe3O4 磁性纳米粒子的合成，用原硅酸四乙酯 (TEOS) (Fe3O4/SiO2) 包覆后者，用 3-氯丙基三甲氧基硅烷 (CPTMS) 和 3-巯基 1,2,4-三唑 (MT) 配体对 Fe3O4/SiO2 进行功能化（ Fe3O4/SiO2/CPTMS/MT)，并与 CuCl2 进一步络合 (Fe3O4/SiO2/CPTMS/MT/Cu)。为了证明其在合成多样性方面的实用性，新的 Cu 磁性纳米催化剂随后被用于通过氨基酸与叠氮化钠和原甲酸三乙酯 (TEOF) 在 40°C 下的 H2O 反应合成各种有用的四唑（方案1）。据我们所知，这是第一个这样的应用程序。在模型反应中优化催化剂活性。这是由色氨酸与叠氮化钠和 TEOF 反应合成 3-(1H-indol-3-yl)-2-(1H-tetrazol-1-yl) 丙酸 (2c)。该模型在不同温度、催化剂用量和溶剂条件下运行。最好的结果是在 407 摄氏度的水中用 10 毫摩尔氨基酸、10 毫摩尔叠氮化钠、30 毫摩尔 TEOF 和 20 毫克铜纳米颗粒催化剂获得的（表 1-3）。应用模型的优化结果，制备了许多具有良好到优异产率的四唑（表 4）。对所有化合物进行了充分表征（参见实验部分）。30mmole TEOF 和 20mg Cu 纳米颗粒催化剂在 407°C 的水中（表 1-3）。应用模型的优化结果，制备了许多具有良好到优异产率的四唑（表 4）。对所有化合物进行了充分表征（参见实验部分）。30mmole TEOF 和 20mg Cu 纳米颗粒催化剂在 407°C 的水中（表 1-3）。应用模型的优化结果，制备了许多具有良好到优异产率的四唑（表 4）。对所有化合物进行了充分表征（参见实验部分）。