Solvoselective effect of Cu–B2O3/porous boron nitride on catalytic conversion of arylboric acids to phenols and biphenyls

A novel Cu–B2O3/porous boron nitride (PBN) composite was developed as a highly efficient and reusable heterogeneous catalyst for the solvent-controlled conversion of arylboronic acids. In water, the catalyst promotes ipso-hydroxylation to phenols, while in methanol, it facilitates aerobic homocoupling to biphenyls, using air as a green oxidant. The synergistic interaction between Cu nanoparticles and B2O3 sites enhances both catalytic activity and stability. This work offers a sustainable and selective approach for synthesizing phenolic and biphenyl compounds under mild conditions.