Visible-light-induced oxidative alkene difunctionalization to access α-sulfonyloxy ketones catalyzed by oxygen-vacancy-rich Nb2O5

Herein, we report an oxygen vacancy (OVs)-rich Nb2O5 semiconductor (OVs-N-Nb2O5) as a bifunctional heterogeneous photocatalyst for unprecedent synthesis of a-sulfonyloxy ketones via oxidative alkene difunctionalization with sodium sulfinate under visible light irradiation and ambient conditions. A broad set of aromatic and aliphatic alkenes was efficiently difunctionalized into diverse a-sulfonyloxy ketones in high yields with a good functional group tolerance. The catalyst OVs-N-Nb2O5 is highly stable and could be easily recovered for at least 6 successive recycles with maintaining photoactivity and selectivity. Experimental and theoretical investigations reveal that the presence of OVs not only accelerates the separation and transfer of photogenerated electron-hole pairs, but also promotes O-2 adsorption and activation to form long-lived superoxide anion radical (O-2 center dot), which greatly boosts the reaction and modulates the reaction pathways together with the intrinsic Lewis acid sites, thereby resulting in an improved reaction activity and excellent selectivity to the desired product.