Visible-Light-Induced Oxidative Coupling of Phenols and Alkenylphenols with a Recyclable, Solid Photocatalyst

A photocatalytic method for phenol and alkenylphenol
oxidative
coupling is reported using an inexpensive heterogeneous titanium dioxide
photocatalyst with air and visible light. During the coupling process,
the Ti–substrate complex is activated under visible light through
a ligand to metal charge transfer effect, and the diphenol adduct
is proposed to form through a radical cation. The heterogeneous TiO2 catalyst remains stable throughout the reaction and can be
easily removed and reused multiple times.