Organophotoredox‐Catalyzed [3 + 2] Cycloaddition for the Diastereoselective Synthesis of Spirocyclopentane Oxindoles

A novel organophotoredox‐catalyzed [3 + 2] cycloaddition strategy for the synthesis of spirocyclopentane oxindoles is reported, employing N ‐aryl cyclopropylamines and isatin‐derived alkenes as readily available coupling partners. This protocol affords diverse spirocyclopentane oxindole derivatives in excellent yields (up to 94%) and good diastereoselectivities (up to 96:4 dr) under mild conditions. The transformation is facilitated by a dual catalytic system consisting of Eosin Y as photoredox catalyst and diphenyl phosphate (PA) as organocatalyst, with N , N ‐diisopropylethylamine (DIPEA) as a crucial additive.