Recyclable Cs₂AgBiBr₆ for Photocatalytic Synthesis of Cyanomethylated Oxindoles

Cyanomethylated oxindoles represent an important class of heterocyclic scaffolds. However, previous synthetic methods often suffer from harsh conditions, such as high temperatures, precious metal catalysts, or toxic cyanating sources, coupled with challenges in catalyst recovery. Herein, we report a novel heterogeneous photocatalytic strategy using the double perovskite Cs₂AgBiBr₆ as a photocatalyst. This methodology enables the visible-light-induced radical cascade cyclization of N-aryl acrylamides with acetonitrile, efficiently producing diverse cyanomethylated oxindoles. This work not only provides a sustainable alternative for the synthesis of these valuable compounds but also highlights the potential of double perovskites in organic photosynthesis.