Ruthenium‐Catalyzed Ortho‐Selective Aromatic CH Borylation of 2‐Arylpyridines with Pinacolborane

The ruthenium-catalyzed dehydrogenative borylation of 2-arylpyridines with pinacolborane took place at ortho-positions of the benzene ring. Density functional theory calculations and kinetic isotope effect experiments suggest that the catalytic cycle should involve oxidative addition of the CH bond, the rate-determining σ-bond metathesis of pinacolborane with the ruthenium hydride complex, and reductive elimination of the CB bond.