Radical cascade cyanomethylation of activated alkenes to construct cyano substituted oxindoles.

The cyanomethyl radical was easily generated from acetonitrile by using DTBP, which was applied to a cascade alkene addition and cyclization reaction to construct useful oxindole derivatives. This protocol features simple manipulation, cheap reagents and a broad substrate scope. In addition, nitro substituted oxindoles were also synthesized for the first time.