α-Diimine-based conjugated microporous polymers as heterogeneous ligands for highly efficient palladium-catalyzed direct C–H arylations

Abstract

Direct C–H bond transformation has long been regarded as the “holy grail of chemistry” in the field of organic synthesis. Significant progress has been achieved in this area with a variety of homogeneous transition-metal catalysts. In contrast, only a few examples of heterogeneous catalysis of direct C–H bond transformation have been reported. In this work, we report the use of new types of α-diimine structure functionalized conjugated microporous polymers (DIM-CMPs) as ligands for heterogeneous catalysis, which show high efficiency and recyclability in Pd-catalyzed direct C–H arylations. These DIM-CMPs are distinguished by their exceptional stability, robust porous framework, and efficacious allocation of palladium active sites, all of which cumulatively contribute to their superior catalytic performance. The superior utility of DIM-Pd-CMPs in catalysis is elucidated by their broad substrate scope (32 examples, 82–98% yields), along with tolerance towards a variety of functional groups, good recyclability (6 times) and the ability to be performed on a gram scale (10 mmol). Moreover, their utility has been highlighted in the synthesis of potentially bioactive molecules through sequential C–H arylation and Suzuki coupling. This innovative development is poised to significantly impact the synthesis of heterobiaryls, which are crucial constituents of a variety of natural products and pharmaceutical compounds, potentially revolutionizing catalysis in industrial applications and offering significant economic and environmental advantages.