Porous Organic Polymer-Supported Palladium Catalyst for Reactive Oxygen Species-Mediated Sustainable One-Pot Flavones Synthesis

The catalytic synthesis of flavones, key intermediates in pharmaceutical development, remains a challenge, particularly the development of efficient one-pot heterogeneous systems suitable for large-scale industrial production. Herein, we report a phenanthroline-functionalized porous organic polymer-supported palladium catalyst (Pd-Phen-DC) that facilitates the highly efficient one-pot oxidative condensation of 2′-hydroxyacetophenone and benzaldehyde to yield flavone. Under optimized conditions, this heterogeneous catalyst achieves flavone yields of up to 98%, with reaction performance significantly influenced by solvent polarity, base selection, and temperature. Mechanistic studies, employing techniques such as electron paramagnetic resonance (EPR) and fluorescence spectroscopy, reveal that the electron-withdrawing ligands incorporated within the polymer backbone enhance the catalyst’s ability to activate molecular oxygen, promoting the formation of reactive oxygen species (ROS) of singlet oxygen and enabling selective oxidation. The catalyst also exhibits broad substrate scope and excellent recyclability, demonstrating its versatility for synthesizing diverse flavone derivatives.