Catalytic Regio- and Stereoselective Alkene Sulfenoamination for 1,4-Benzothiazine Synthesis.

An alkene sulfenoamination reaction with 2-aminothiophenol is developed using iodide catalysis. This reaction renders access to useful 1,4-benzothiazines with good functional group compatibility including both electron-donating and electron-withdrawing substituents. The reaction is proposed to proceed through an inversion of the polarity of the thiol functionality. Our mechanistic studies reveal that both thiiranium and thiyl radical pathways are plausible and that the disulfide reagent can also function as a viable substrate in this reaction.