Oxygen-atom transfer in titanium dioxide photoredox catalysis for organic synthesis

Recent developments in organic synthesis driven by TiO₂ photoredox catalysts are highlighted in this chapter. The latest discoveries indicate that TiO₂, a prototypical semiconductor photoredox catalyst, is an excellent platform for O-atom transfer because (1) it is capable of adding O-atoms onto organic molecules from O₂ with the assistance of electrons and (2) it is suited for removing the O-atoms from oxygen-containing molecules with the assistance of protons. Because O-atom transfer is central to the majority of organic redox transformations, understanding the mechanisms of O-atom transfer is essential to figuring out the mechanism of photoredox catalysis and the selective transformations of new organic substrates at the surface of TiO₂. This highlight serves to further expand the realm of O-atom transfer (i.e., oxygenation or deoxygenation) in heterogeneous photoredox catalysis for organic synthesis.