The first stereoselective synthesis of optically active thiosulfinates

Treatment of optically active $\text{p}$-toluenesulfinamides (1) with thiols (2) in the presence of trifluoroacetic acid was found to give optically active $\text{p}$-toluenethio-sulfinates (3) with predominant inversion of configuration. Stereospecificity of this reaction varies from 30 to 80%. Some mechanistic aspects of the reaction are also discussed.