Fe‐Photocatalyzed Decarboxylative Giese‐Type Reaction of α‐N, O or S Carboxylic Acids: Insight into the Mechanism of the Radical Formation

Very simple conditions are described for the Fe‐photocatalyzedaddition of α‐amino, α‐alkoxy, and α‐alkylthio radicals to electron‐deficient alkenes. The reactions proceed under smooth ligandless conditions with inexpensive base and in the absence of oxidant. A mechanistic computational TD‐DFT study on the formation and evolution of the electronic excited states supports for the first time that, after Fe(III)‐carboxylate excitation by visible light, homolytic cleavage of the FeO actually takes place, leading to a carboxyl radical.