Xantphos-Cu-Decorated Covalent Organic Frameworks for C─H Arylation through Sensitized Electron Transfer.

The isoindolinone scaffold is an important structural motif found in a wide range of naturally occurring and synthetic biologically active compounds. However, the synthesis of isoindolinone derivatives typically requires multi-step procedures or the use of palladium-based catalysts, which are often hampered by low reaction yields and high costs. Recently, covalent organic frameworks (COFs)-emerging crystalline and porous materials-have gained considerable attention for their applications in various organic transformations, particularly in C─H functionalization, cross-coupling and redox reactions. Although COFs have been extensively studied for photocatalysis, the development of sustainable heterogeneous catalysts using low-cost transition metal-based photosensitizers is still in its early stages. Herein, a strategy is presented to incorporate a copper-Xantphos complex with a tetrahedral Cu(I) geometry into a crystalline and porous COF matrix. This modification enables unprecedented simultaneous electron and energy transfer efficiency during photocatalysis. The Cu-Xantphos coordinated COF exhibits potent photocatalytic activity for the synthesis of isoindolinone derivatives via C─Br and C─H bond cleavage followed by C─C bond formation. In addition, the catalyst shows excellent recyclability as it can be rejuvenated by reintroducing the Cu-Xantphos complex after multiple photocatalytic cycles-highlighting its potential as a sustainable and cost-effective solution for valuable organic transformations.