Photocatalytic hydrogen atom transfer: the philosopher's stone for late-stage functionalization?

An overview about the potentialities of photocatalytic Hydrogen Atom Transfer (HAT) for the Late-Stage Functionalization (LSF) of complex molecules is offered. The examined approach allows the smooth homolytic cleavage of the C–H bonds embedded in the substrate, offering a straightforward access to valuabe C-centred radical intermediates to be exploited for the desired transformations. The examples have been classified according to the species responsible for the activation of the substrate, also showcasing the opportunities in terms of selectivity offered by the different alternatives.