Catalytic Double Carbon–Boron Bond Formation for the Synthesis of Cyclic Diarylborinic Acids as Versatile Building Blocks for π‐Extended Heteroarenes

The first catalytic synthesis of cyclic diarylborinic acids is developed using a dihydroaminoborane reagent as the boron source. Unlike previously reported methods that use organolithium reagents, this method allows the easy synthesis of cyclic diarylborinic acids bearing a range of functionalities including CN, CO₂Et, CONEt₂ and NMeCO₂^t Bu. Furthermore, these cyclic diarylborinic acids provide rapid access to skeletal diversity, in particular they enable the synthesis of six‐ to nine‐membered π‐extended heteroarenes through simple cross‐coupling reactions, which are important synthetic targets in both advanced materials and pharmaceuticals.