Polymeric Iridium Catalysts for C–H Borylation of Arenes under Batch and Continuous Flow Conditions

Arylboronates are key intermediates in the synthesis of pharmaceuticals and functional materials, yet their direct C–H borylation typically requires air-sensitive homogeneous iridium catalysts, limiting catalyst recovery and scalability. Here we show that pyridine-containing polymer-supported Ir catalysts can promote C–H borylation under both batch and continuous flow conditions. A ternary copolymer synthesized from 4-vinylpyridine, 4- tert -butylstyrene, and N -isopropylacrylamide served as an effective support for immobilizing and stabilizing the Ir species, yielding the polymeric Ir catalyst. This catalyst enabled batch C–H borylation of 20 arenes with yields up to 87% and continuous flow synthesis of borylated products under air, producing multiple compounds in a single reactor over 42 h. XAFS analysis revealed partial reduction of the Ir(III) precursor during catalyst preparation and in situ during the borylation reaction. This study provides a practical approach for designing immobilized iridium catalysts, advancing the scalable application of C–H borylation reactions.