Synthesis of C3-Fluorinated Oxindoles through Reagent-Free Cross-Dehydrogenative Coupling.

Reported herein is an unprecedented synthesis of C3-fluorinated oxindoles through cross-dehydrogenative coupling of C(sp3 )-H and C(sp2 )-H bonds from malonate amides. Under the unique and mild electrochemical conditions, the requisite oxidant and base are generated in a continuous fashion, allowing the formation of the base- and heat-sensitive 3-fluorooxindoles in high efficiency with broad substrate scope. The synthetic usefulness of the electrochemical method is further highlighted by its easy scalability and the diverse transformations of the electrolysis product.