Recent advances in transition-metal-catalyzed selective oxidation of substituted phenols and methoxyarenes with environmentally benign oxidants

• Recent advances in selective oxidation of substituted phenols and methoxyarenes are reviewed.
• Quinones are versatile building blocks in the synthesis of biologically active compounds.
• Transition-metal catalysis offers an efficient access to substituted quinones and quinols.
• Emphasis is given to use of environmentally benign oxidants.
• Mechanistic features and stability of catalysts are discussed.

The selective catalytic oxidation of organic compounds with atom-efficient, cheap and readily available oxidants is widely recognized as the most economic and ecological route to many valuable oxygen-containing products and intermediates of organic synthesis. In the last two decades, a considerable scientific effort was directed to the development of catalytic systems that employ environmentally benign oxidants to convert aromatic compounds to oxygenated products, which serve as versatile building blocks in the synthesis of vital biologically active compounds. The present review summarizes recent advances in transition-metal-catalyzed liquid-phase selective oxidation of substituted phenols and methoxyarenes with molecular oxygen, hydrogen peroxide, and t-butyl hydroperoxide, covering both homogeneous and heterogeneous catalysts. The review highlights the scope and limitations of the existing methods and discusses mechanistic features of these important catalytic oxidation reactions. For solid catalysts, special attention is paid to analysis of the critical issues of the nature of catalysis, metal leaching under conditions of liquid phase oxidation reactions, and catalyst reusability.

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