An economical and environmentally friendly oxidative biaryl coupling promoted by activated MnO2.

An activated manganese dioxide (MnO2) BF3 center dot OEt2 oxidation system was developed to efficiently mediate the intramolecular as well as intermolecular biaryl coupling. The oxidative coupling proceeds smoothly at ambient temperature to deliver the corresponding five- to eight-membered tricyclic products in good to excellent yields. The employment of the combination of MnO2 and BF3 center dot OEt2 is attractive on the basis of economical and environmental issues.