Recyclable Acid–Base Bifunctional Core–Shell–Shell Nanosphere Catalyzed Synthesis of 5‐Aryl‐1 H ‐1,2,3‐triazoles through the “One‐Pot” Cyclization of Aldehydes, Nitromethane, and Sodium Azide

• Published in: ChemCatChem 2017-08, Vol.9 (16), p.3131-3137
• Main Authors: Liu, Lei, Ai, Yongjian, Li, Dong, Qi, Li, Zhou, Junjie, Tang, Zhike, Shao, Zixing, Liang, Qionglin, Sun, Hong‐Bin
• Format: Article
• Language: English
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201700401

A magnetically separable core–shell–shell nanosphere, Fe 3 O 4 @nSiO 2 ‐SO 3 H@MS‐NHCOCH 3 (n=nonporous, MS=microporous SiO 2 ), was fabricated as an acid–base collaborative catalyst for the three‐component cyclization of aromatic aldehydes, nitroalkane, and sodium azide to afford 1 H ‐1,2,3‐triazoles. The bifunctional heterogeneous catalyst showed high activity for this transformation and good chemoselectivity, and toxic HN 3 was not released during the course of the reaction. A variety of aldehydes were transformed into the corresponding 5‐aryl‐1 H ‐1,2,3‐triazoles in up to 98 % yield. Furthermore, the catalyst could be recovered by using an external magnetic field and reused many times without any loss in activity. In contrast, a homogeneous catalyst system comprising ammonium acetate/acetic acid also worked in this three‐component cyclization to afford 1 H ‐1,2,3‐triazoles.