Carbon-carbon bond formation between cyclobutylanalines and tetrahydrofuran using a titanium based photocatalyst

by Calaway, Mark G.; Zheng, Nan

Recently, the use of titanium dioxide based materials to harvest visible light has attracted enormous interest due to its superior photochem. stability, non-toxic characteristics, low cost and chem. reactivity. By partially reducing Ti4+ in TiO2 to Ti3+, that Ti3+ or O vacancies are generated, the band gap of TiO2 (3.2 eV) can be lowered down and the new TiO2@Ti3+ has been reported to absorb visible light. The visible light photocatalyst TiO2@Ti3+ is used in a heterogeneous catalysis system to facilitate the opening of cyclobutylanilines. This ring opening leads to the formation of a terminal alkyl radical that is quenched by a hydrogen transfer from THF. The THF then reacts with the imminium ion, which is formed through the ring opening, and forms a carbon-carbon bond with THF to create a product with diastereoselctivity. This Photochem. process can be used with different functionalities on the six membered ring of the cyclobutylaniline. This is another very useful application for Photochem. using visible light photocatatlysis.