Metal-free nitro-carbocyclization of activated alkenes: a direct approach to synthesize oxindoles by cascade C-N and C-C bond formation

A novel and direct metal-free nitro-carbocyclization of activated alkenes leading to valuable nitro-containing oxindoles via cascade C-N and C-C bond formation has been developed. The mechanistic study indicates that the initial NO and NO2 radical addition and the following C-H functionalization processes are involved in this transformation.