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

Abstract

AbstractA magnetically separable core–shell–shell nanosphere, Fe3O4@nSiO2‐SO3H@MS‐NHCOCH3 (n=nonporous, MS=microporous SiO2), was fabricated as an acid–base collaborative catalyst for the three‐component cyclization of aromatic aldehydes, nitroalkane, and sodium azide to afford 1H‐1,2,3‐triazoles. The bifunctional heterogeneous catalyst showed high activity for this transformation and good chemoselectivity, and toxic HN3 was not released during the course of the reaction. A variety of aldehydes were transformed into the corresponding 5‐aryl‐1H‐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 1H‐1,2,3‐triazoles.