Visible-light excited copper activating unactivated alkyl iodides for radical addition/cyclization to access oxindole derivatives

Herein, we introduce copper-catalyzed cascade radical addition/cyclization reactions for the synthesis of oxindole derivatives. The in situ generated copper complex can solely serve as a standalone photocatalyst. The generation of alkyl radicals from unactivated alkyl iodides can be achieved by copper catalysis under visible-light irradiation at room temperature in the absence of any additives or oxidants. Various functional groups are well compatible. Primary, secondary, and tertiary alkyl iodides all exhibit good reactivity, leading to products with good yields. The photocopper catalyst facilitates halogen atom transfer to give unactivated alkyl radicals, which is critical for achieving radical cyclization in the absence of an exogenous photocatalyst.