Magnetite (Fe3O4) Nanoparticles: An Efficient and Reusable Catalyst for the Synthesis of Thioethers, Vinyl Thioethers, Thiol Esters, and Thia-Michael Adducts under Solvent-Free Condition

Magnetically recoverable nanoparticles (MNPs) represent an economical, practical and environmentally benign means for catalyst recovery, providing catalytic properties intermediate between homogeneous and bulk heterogeneous materials. In recent years, nano Fe3O4 (magnetite) has attracted a great attention as heterogeneous catalyst due to its simple handling, ease of recovery with an external magnetic field, oxidative stability, biological compatibility, and high catalytic activities in various organic transformations. The construction of carbon–sulfur bond, especially under a green and safe condition, is an important transformation in organic synthesis. Sulfur containing compounds are found in many products of biological and medical relevance as well as in commercial drugs. Among them, thioethers (sulfides) and thiol esters are two important classes of organosulfur compounds. In continuation of our interest in applications of Fe3O4 MNPs for organic transformations, herein, we report a robust and magnetically reusable Fe3O4 nanoparticle catalyzed reaction of thiols with alkenes, alkynes, alkyl- and acyl halides. A diverse range of thioethers, vinyl thioethers, and thiol esters were obtained in moderate to excellent yields under neat and aerial conditions at room temperature. The catalyst was recycled and reused eight times with minor decrease in its catalytic activity.