Cascade Trisulfur Radical Anion (S3•-) Addition/Electron Detosylation Process for the Synthesis of 1,2,3-Thiadiazoles and Isothiazoles.

Trisulfur radical anion (S3•-) mediated reactions with in situ formed azoalkenes and α,β-usaturated N-sulfonylimines for the construction of 1,2,3-thiadiazoles and isothiazoles has been developed. S3•- is in situ generated from potassium sulfide in DMF. These two approaches provide a new, safe, and simple way to construct 4-subsituted 1,2,3-thiadiazoles, 5-subsituted 1,2,3-thiadiazoles, and isothiazole in good yields. The reactions include the formation of the new C-S and N-S bonds via S3•- addition and electron detosylation under mild conditions.