Titanocenes as Photoredox Catalysts Using Green-Light Irradiation

Area of Science:

• Organometallic Chemistry
• Photocatalysis
• Organic Synthesis

Background:

• Titanium complexes are widely studied for their catalytic properties.
• Photoredox catalysis offers a sustainable approach to chemical transformations.
• Developing new molecular photoredox catalysts is crucial for advancing synthetic methodologies.

Purpose of the Study:

• To investigate the photophysical properties of Cp2TiCl2 upon green light irradiation.
• To evaluate the potential of electronically excited [Cp2TiCl2]* as a photoredox catalyst.
• To demonstrate the utility of this titanium complex in organic synthesis, specifically for epoxide reduction and cyclization.

Main Methods:

• Photochemical irradiation of Cp2TiCl2 with green light.
• Characterization of the electronically excited state [Cp2TiCl2]*.
• Application of the excited complex as a catalyst in reduction reactions of epoxides.
• Utilizing the catalyst in 5-exo cyclizations of unsaturated epoxides.

Main Results:

• Irradiation of Cp2TiCl2 with green light generates an electronically excited state, [Cp2TiCl2]*.
• The excited complex [Cp2TiCl2]* demonstrates high efficiency as a photoredox catalyst.
• Successful reduction of epoxides was achieved using this catalytic system.
• Efficient 5-exo cyclizations of suitably unsaturated epoxides were accomplished.

Conclusions:

• The electronically excited [Cp2TiCl2]* complex is a potent molecular photoredox catalyst.
• This study presents the first example of a molecular titanium photoredox catalyst.
• The developed system offers a novel and efficient route for epoxide transformations and cyclizations.