Synthesis of Hydroxyl-Containing Oxindoles and 3,4-Dihydroquinolin-2-ones through Oxone-Mediated Cascade Arylhydroxylation of Activated Alkenes

Hydroxyl-containing compounds are highly value-added organic molecules, and the establishment of novel methodologies for their elaboration is a long-standing challenge in organic synthesis. Here the first oxone-mediated direct arylhydroxylation of activated alkenes was developed for the synthesis of valuable hydroxyl-containing oxindoles and 3,4-dihydroquinolin-2-ones. The products were controlled by adjusting the structure of the starting alkenes. Moreover, the reaction was performed under simple conditions without any external additives or catalysts. Primary mechanistic studies showed that this reaction was a tandem process involving epoxidation and subsequent Friedel–Crafts alkylation, and oxone played a dual role (both the oxidant and proton source) in this process.