Cp2TiIIICl Catalysis in a New Light

Visible‐light‐mediated photogeneration of Cp2TiIIICl has opened new avenues for titanium catalysis. The synergistic utilization of dual photoredox and Cp2TiIIICl catalysis uses Hantzsch ester (HE) as an electron donor instead of traditional super‐stoichiometric metallic reductants. This new paradigm has found numerous applications in synthetic organic chemistry. The highly efficient photoinduced electron transfer process between light‐sensitive Cp2TiCl2 and an excited photocatalyst is the key to the success of such a photocatalytic system and ensures overall catalyst turnover. Comparisons between the metal reduction approach and photo reduction approach have been made. Visible‐light‐mediated photogeneration of Cp2TiIIICl has opened new avenues for titanium catalysis. The synergistic utilization of dual photoredox and Cp2TiIIICl catalysis has found numerous applications in synthetic organic chemistry, including reductive opening of epoxides, cyclization of epoxyalkynes, reductive coupling, and Barbier‐type allylation. The highly efficient photoinduced electron‐transfer process between light‐sensitive Cp2TiCl2 and an excited photocatalyst is the key to the success of such a photocatalytic system.