Synthetic Applications of Photocatalyzed Halogen-Radical Mediated Hydrogen Atom Transfer for C−H Bond Functionalization

The opportunity to activate C(sp³)−H bonds via homolytic cleavage by means of halogen radicals has long been disregarded in synthetic endeavors due to the unpredictable selectivity. Nowadays, photocatalysis has established itself as a method of choice for the generation of such reactive intermediates under mild conditions. This Minireview collects recent examples showcasing how photocatalytic manifolds have been used to tame aggressive halogen radicals to activate C(sp³)−H bonds via Hydrogen Atom Transfer (HAT) for synthetic purposes. In the last section of this work, we address site-selectivity issues posed by this methodology and show how it can be guided through the judicious choice of reaction conditions.