Neutral Aqueous, Visible-Light-Accelerated Rh(III)-Catalyzed C–H Bond Activation/Cyclization Applicable to Peptide Modification

Conventional Rh(III)-catalyzed C-H activation/cyclization of arenes with iodonium ylides typically requires organic solvents, increased temperatures, and a non-neutral reaction medium, which limits their compatibility with biologically relevant substrates. Herein, we disclose a visible-light-enabled Rh(III)-catalyzed C-H activation/cyclization of amines with 1,3-diketones in neutral aqueous media, delivering tetrahydrocarbazolones, indoles, and indolinones with high selectivity. The transformation operates under ambient conditions using sunlight, eliminates the need for strong bases or organic solvents, and permits rapid and solid Rh(III) catalyst recycling. Importantly, the method tolerates peptide substrates and holds promise for late-stage functionalization under genuinely biocompatible conditions.