Copper in Photocatalysis

Light-induced electron transfer (Cu-I to Cu-II), oxidative addition (Cu-I to Cu-III), or the activation of copper alkene or alkyne complexes are possible key steps that offer unique possibilities for organic synthesis, including [2+2]-cycloadditions, cross-coupling reactions or atom transfer radical additions. This Minireview provides an overview on the photophysical properties of photocatalysts based on copper and on synthetic transformations mediated by them.