Combined Photoredox and Iron Catalysis for the Cyclotrimerization of Alkynes.
Michael NeumeierUttam ChakrabortyDieter SchaarschmidtVictor de la Pena O'SheaRaul Perez-RuizAxel Jacobi von WangelinPublished in: Angewandte Chemie (International ed. in English) (2020)
Successful combinations of visible-light photocatalysis with metal catalysis have recently enabled the development of hitherto unknown chemical reactions. Dual mechanisms from merging metal-free photocatalysts and earth-abundant metal catalysts are still in their infancy. We report a photo-organo-iron-catalyzed cyclotrimerization of alkynes by photoredox activation of a ligand-free Fe catalyst. The reaction operates under very mild conditions (visible light, 20 °C, 1 h) with 1-2 mol % loading of the three catalysts (dye, amine, FeCl2 ).