Synthesis of Phenolic Compounds via Palladium Catalyzed C-H Functionalization of Arenes.

Phenol and its derivatives are extremely useful compounds in organic synthesis, medicinal chemistry and material sciences. The synthesis of phenols involving selective construction of the C-O bond at a C-H bond of arenes using transition-metal catalysis represents the most appealing strategy. Indeed, active research is currently going on for the synthesis of valuable phenolic compounds using a transition-metal-catalyzed C-H functionalization strategy. This short review summarizes recent advances on palladium-catalyzed C-O bond forming reactions that enable direct access to phenolic compounds. These catalytic reactions proceed either via C-H esterification with trifluoroacetic acid/trifluoroacetic anhydride followed by in situ hydrolysis of the ester or via direct C-H hydroxylation. A brief analysis of substrate scope and limitation, reaction mechanism as well as synthetic utility of these reactions has been included.