Heterogeneous Light-Mediated Reductive Dehalogenations and Cyclizations Utilizing Platinum Nanoparticles on Titania (PtNP@TiO2)

The utility of platinum nanoparticles on titania (PtNP@TiO2) as a heterogeneous photoredox catalyst is evaluated using a series of reductive transformations. In comparison to TiO2 alone, TiO2 decorated with 0.2% PtNP shows enhanced efficiency, attributed to the NPs ability to both enhance light absorption and inhibit electron-hole pair recombination. Herein, we demonstrate that under an inert atmosphere and UVA/visible light irradiation a system consisting of our PtNP@TiO2 catalyst in conjunction with a sacrificial electron donor [diisopropylethylamine, (i-Pr)(2)NdEt] can promote a variety of different reductive dehalogenations and cyclizations in moderate to excellent yields. In addition, the catalytic system is tolerant of many different functionalities and, due to its heterogeneous nature, holds the advantage of easy catalyst removal.