Metal-free trifluoroethylation of activated alkenes: rapid access to construct fluorinated 3,3-disubstituted 2-oxindoles

A novel and mild fluorination/cyclization reaction of activated alkenes under metal-free conditions has been developed. Fluorinated radicals were produced from halogenated hydrocarbons by simple rongalit, meanwhile, no metal and extra base are needed. This method provides a general and rapid route to construct fluorinated 2-oxindoles in aqueous solution.