Photochemical Radical Cascade Annulation of 6-Azauracils Enabled by CsPbBr3 Perovskite Nanocrystals

Abstract Direct annulation of 6-azauracils has remained challenging due to their strongly electron-deficient and decomposition-prone heterocyclic frameworks. This study presents unique insight into the core modification of the 6-azauracil system enabled by a CsPbBr3 perovskite nanocrystal-promoted photochemical cascade cyclization with an amino acid derivative. N-Phenylglycine, a zwitterion with strong surface binding affinity for the photocatalyst, generated a nucleophilic aminomethyl radical in dimethyl carbonate that added to the C═N bond, triggering a radical cascade to tetrahydroimidazole-fused triazines, structures of emerging relevance in biochemical applications. Dimethyl carbonate ensured radical stability and catalyst integrity, enabling a broad scope and late-stage functionalization. Beyond azauracils, the strategy also supports the late-stage functionalization of a range of biologically important drug molecules, providing a cost-effective, sustainable, and operationally simple platform for light-mediated synthesis empowered by perovskite nanocrystals.