Recent Advancements on Transition‐Metal‐Catalyzed, Chelation‐Induced ortho‐Hydroxylation of Arenes

The phenols are key intermediates as well as desired products in many target oriented syntheses. The conversion of C−H bond to C−O bond is one of the most challenging tasks in organic synthesis. In last few decades, the hydroxylation of aromatic compounds has drawn a considerable attention because of their importance in Pharmaceutical industry, material chemistry, polymers and in agrochemicals. Indeed, transition‐metal‐catalyzed, coordination‐assisted regio‐ and chemoselective ortho‐hydroxylation of arenes has become very efficient and popular strategy to obtain good yields of phenols with tolerance of a wide range of functional groups. This review is the comprehensive summary of recent advancement on Pd‐, Ru‐, Rh‐, Cu‐ and Ir‐catalyzed, chelation‐controlled regioselective ortho‐C−H bond hydroxylation of aromatic compounds in the presence of diverse hydroxylating agents. The review has been classified on the sources of hydroxylating agents used in reaction.