Study On Copper Catalyzed C-S Cross-coupling Of Using KF/Al₂O₃ As Base

The formation of C(aryl)-S bonds represents a key step in the synthesis of many molecules that are of biological, pharmaceutical, and material interest. However, traditional methods for the synthesis of aryl-sulfur bonds often require harsh reaction conditions. Such as high temperature, the usual requirement of stoichiometric amounts of copper reagents, long reaction times and low yields. The development of transition metal-catalyzed coupling has overcome these difficulties to a great extent. On the other hand, modern transition-metal (palladium, nickel, copper, cobalt, iron and indium) in combination with appropriate ligands for catalyzed cross-coupling reactions of aryl halides with thiols enable the synthesis of aryl sulfides in good yields under milder reaction conditions. However, the high cost and air sensitivity of Pd catalysts and often tedious procedure for the preparation of ligands restrict their applications in large-scale processes. On the other hand, in general, Co and Ni catalysts are associated with toxicity. Thus, development of alternative inexpensive, ligand-free, non-air sensitive catalysts for this useful reaction is highly desirable in the context of environmental and industrial concerns.In order to overcome these drawbacks,Our group,based on the previous work about the coupling reaction of aryl halides with alkyl thiols. After optimization of reaction conditions such as solvents, temperatures,bases,copper reagents etc,we found all effective catalytic system: Copper-catalyzed S-arylation of aryl and alkyl thiols with aryl iodides using KF/Al2O3 as base at 110℃under N2 can be successfully carried out which offers a convenient, environmentally benign, ligand-free and efficient alternative to this practical transformation. We believe that the application to KF/Al2O3 will provide new idea for a wide array of organic reactions.