Cobalt catalyzed meta selective C–H activation of diverse classes of arenes

Achieving remote and regioselective C–H functionalization of arenes with earth-abundant metals remains a central challenge in sustainable synthesis. Here we report a cobalt-catalyzed manifold that offers a general solution for achieving excellent meta C–H borylation across diverse classes of arenes. The key to this advance is a non-organometallic activation strategy in which a Co(II) precatalyst is converted in situ into an active Co(I) species through cooperative action of a newly designed terpyridine ligand, B₂pin₂, and KOtBu. Operational simplicity and unique mode of activation renders this method a sustainable and suitable alternative to iridium-based borylation paradigms. Mechanistic analyses and DFT studies support that the active species is a radical Co(I) ate-complex, whose ligand-centric radical character and counterion-stabilized electronic structure enable a unique, non-conventional pathway that is fundamentally different from conventional neutral Co(I) systems. This study presents an unusual blend of sustainability, ease of operation, and mechanistic novelty, expanding the limits of cobalt catalysis and providing a widely applicable approach for the selective functionalization of arenes.