Water as a Hydroxy Source in a RhIII‐Catalyzed Directed C−H Hydroxylation of 2‐Arylpyridines

A [RhIIICp*]‐catalyzed directed C−H hydroxylation of 2‐arylpyridines is described (Cp*=1,2,3,4,5‐pentamethylcyclopenta‐2,4‐dienyl), in which the combination of [(RhCp*Cl2)2]/AgF, PhI(OPiv)2, and water is used an effective catalytic system. According to our mechanistic studies, including 18O‐labeling experiments and X‐ray crystallographic analysis of an intermediate Rh complex, we demonstrate that water and PhI(OPiv)2 are required for Rh catalysis as the hydroxy source and the oxidant, respectively. Three and easy: The directed C−H hydroxylation of 2‐arylpyridines was efficiently catalyzed by [(RhCp*Cl2)2] and AgF in 38–93 % yield. Mechanistic investigation indicated that the 2‐(pyridin‐2‐yl)phenol O atom was transferred from water.