Photochemical fluorination reactions - A promising research field for continuous-flow synthesis

The unique properties of fluorine resulting from its tremendously high electronegativity make it a key player in the quest of enabling new and advanced qualities for chemical compounds and materials. With the advent of fluorinating reagents, a great diversity of synthetic methodologies has been developed to incorporate fluorine or fluorine-containing groups into small molecules with high conversion and selectivity. Especially photochemically catalyzed fluorination reactions proved their potential for the synthesis of fluorine-containing fine chemicals due to their mild reaction conditions. This tutorial review gives an overview of recently published synthesis strategies that use (visible-) light-absorbing catalysts for the activation of fluorinating reagents. A special focus lies on the use of continuous-flow microreactors for photochemically catalyzed fluorination reactions due to the excellent utilization of this reactor equipment for photochemistry.