Photoinduced Palladium-Catalyzed 1,2-Difunctionalization of Electron-Rich Olefins via a Reductive Radical-Polar Crossover Reaction

Palladium-catalyzed cross-coupling reactions belong to the most important transformations for the construction of C-C or C-heteroatom bonds. More recently, the photochemical activation of palladium complexes emerged as a key strategy to leverage palladium catalysis at room temperature beyond the scope of conventional cross-coupling chemistry. Herein, we report on the photoinduced palladium-catalyzed 1,2-difunctionalization reaction of electron-rich olefins. Mechanistic experiments and computational studies reveal that this reaction proceeds via the addition of an alkyl radical, followed by the oxidation of a radical intermediate to access carbocation intermediates, which are inaccessible via classic thermal reaction conditions. The carbocation can then be applied to a variety of secondary C-C or C-N bond-forming reactions. This strategy now allows a general approach toward densely functionalized unsymmetric 1,1-bis(heterocyclyl)alkanes.

Automated summary

Palladium-catalyzed cross-coupling reactions are important transformations for building C-C or C-heteroatom bonds. Recently, the use of photochemical activation of palladium complexes has expanded the scope of palladium catalysis beyond conventional cross-coupling chemistry. In this study, the photoinduced palladium-catalyzed 1,2-difunctionalization reaction of electron-rich olefins was investigated. Mechanistic experiments and computational studies revealed that this reaction proceeds through the addition of an alkyl radical and oxidation of a radical intermediate to access carbocation intermediates. These carbocation intermediates can then participate in various secondary C-C or C-N bond-forming reactions, enabling the synthesis of densely functionalized unsymmetric 1,1-bis(heterocyclyl)alkanes.