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 ).
Keywords: alkynes; cycloaddition; iron; photocatalysis; synthetic methods.
© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.