Titanocenes as Photoredox Catalysts Using Green-Light Irradiation.

Irradiation of Cp2 TiCl2 with green light leads to electronically excited [Cp2 TiCl2 ]*. This complex constitutes an efficient photoredox catalyst for the reduction of epoxides and for 5-exo cyclizations of suitably unsaturated epoxides. To the best of our knowledge, our system is the first example of a molecular titanium photoredox catalyst.