Mn(OAc) 3 -Promoted Sulfonation-Cyclization Cascade via the SO 3 - Radical: The Synthesis of Heterocyclic Sulfonates.

Herein we reported a Mn(OAc) 3 · 2H 2 O promoted radical sulfonation from functionalized alkenes and potassium metabisulfite (K 2 S 2 O 5 ). The reaction realized the construction of oxindole, quinolinone, isoquinoline-1,3-dione, or benzoxazine structural fragments and the introduction of sulfonic moieties in one step. More than 50 heterocyclic sulfonates or their derivatives with various substituents were successfully prepared with high efficiency under mild conditions.