Despite extensive efforts in metal-free synthesis, strained cyclic diacyl peroxides have not been invoked as external oxidants in high-oxidation-state palladium-catalyzed reactions and their involvements in corresponding elementary steps were not studied. Herein, a PdII-catalyzed intramolecular oxidative C‒H amination has been successfully developed for the construction of carbazole architectures under additive-free and mild conditions. The presented method proved to be compatible with a variety of functional groups and scalable synthesis, which enabled the late-stage diversification of bioactive molecules as well as facilitated concise syntheses of carbazole alkaloid derivatives. Importantly, the use of strained cyclic diacyl peroxides as a sacrificial oxidant is critical for controlling the reactivity of high-valent Pd intermediates and the selectivity to multiple competing reductive elimination events, owing to the rigid constraint imposed by the bidentate dicarboxylate ligand. Mechanistic studies suggested that this reaction proceeds via a unique PdII/PdIV manifold, and the turnover-limiting step is substrate coordination to palladium catalyst. Moreover, photophysical investigation showed that varying N-protecting groups and increasing conjugated systems had a clear influence on the photophysical properties of carbazole derivatives. The calculation of six green metrics demonstrates the latent greenness of this catalytic system.

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