Syntheses of Sulfides via Wittig Reaction using Thiosulfonates

The sulfur compounds are widely used in organic synthesis and the importance of sulfides, sulfoxides and sulfones not only to increase the structural complexity of organic molecules but also in asymmetric reactions is unquestionable.1 The most common pathway to synthesize sulfides is based on the use of thiols and halides,2 however this strategy has some limitations, especially with regard to the use of thiols, compounds with an unpleasant odor. Thus, despite the plethora of methods for the synthesis of sulfides, the development of a simple and reliable method for the synthesis of this class of compounds would be of the great interest. In this context, thiosulfonates have been widely used in many reactions due to their greater stability and ease of handling.3 This work describes the use of thiosulfonates and commercially available phosphonium salts for the synthesis of sulfides. In the course of developing milder reaction conditions, thiosulfonate 1 and phosphonium salt 2, were used as model compounds and treated at room temperature with different bases and solvents. The progress of the reaction was monitored by TLC and the results are depicted in Table 1. From Table 1 it can be seen that the most efficient method for the synthesis of sulfide 3 was when triethylamine was used as a base in dichloromethane (Table 1, entry 6). In summary, we have shown an efficient method for the synthesis of non-symmetrical sulfides from thiosulfonates and phosphonium salts. The method is simple, fast and general allowing further applications in the synthesis of more complex compounds.