Convenient Preparation of N-sulfonylimines Using Iron-Based Magnetic Nanomaterials

Activated aldimines are important intermediates in organic synthesis [1]. Their durability for long time and mild reactivity have led them to use in many organic reactions which can be pointed to reactions such as Diels–Alder reactions, radical reactions, nucleophilic additions and ene reactions also [2]. The facile way to prepare these compounds is the use of direct condensation of sulfonamide and various aldehydes, although the preparation of water is no favor. Several ways have been developed to accelerate this reaction by using different additives such as AlCl3, ZrO2/S2O8, TiCl4/Et3N, P2O5/SiO2, montmorillonite K-10 and so on. However, harsh reaction conditions, sensitivity to water, low yields and high catalysts loading limited these reactions [3]. In other side, the use of nanoparticles due to the high surface-to-volume ratio, easy recycling and reusing is a good strategy for increasing the efficiency of chemical reactions. Iron-based magnetic nanomaterials have been used as catalysts for a very wide range of catalytic processes and organic transformations such as coupling reactions, C-H activation, oxidation reactions, reduction reactions and synthesis of heterocyclic. Hence, magnetic nanocatalysts due to their pervasive applications on the field of catalysis are of high demand. In this work, initially different nanoparticles were prepared, then the catalytic activity of obtained heterogeneous catalysts was investigated on the reaction between aromatic aldehydes and p-toluenesulfonamide. By optimization of the reaction conditions, various N-sulfonyl imines were afforded in high yields. After the completion of the reaction, heterogeneous catalyst was separated by a magnet form the reaction mixture and reused. The obtained products were characterized by melting point, Ft-IR 1HNMR, 13CNMR spectra.