Recyclable Heterogeneous Supported Copper-Catalyzed Coupling of Thiols with Aryl Halides: Base-Controlled Differential Arylthiolation of Bromoiodobenzenes

Alumina-supported copper sulfate efficiently catalyzes the S-arylation of aromatic, heteroaromatic and aliphatic thiols with aryl as well as heteroaryl halides under aerobic, ligand-free conditions. This protocol provides an easy access to a variety of thioethers as well as unsymmetrical bis-thioethers by base-controlled differential coupling of thiols with iodo- and bromo-substituents in an aromatic halide. The catalyst is inexpensive, non-air sensitive, environmentally friendly and recyclable.