Synthesis of C2 symmetric hydroxylated biphenyls by microwave-assisted oxidative coupling of natural phenols

Phenolic compounds, abundant in various plants, exhibit a range of biological properties such as anti-inflammatory, antiseptic, and antioxidant activities. C2-symmetric biphenyl structures, present in many pharmacologically active substances, serve as fundamental backbones in many natural products, highlighting the significance of these compounds. This study introduces innovative microwave-assisted oxidative coupling methods for the synthesis of C2 hydroxylated biphenyls starting from thirteen natural phenols, focusing on eco-friendliness and efficiency. This approach aims to minimize environmental impact while emphasizing safety and sustainability by employing microwaves in environmentally sustainable solvents like water. The proposed mechanisms for the oxidative coupling of phenols include various possible reaction pathways, encompassing both homo and hetero radical-radical couplings.