Metal-Free, Site-Selective C-H Fluorination of Heteroarenes Under Visible Light

The site-selective C-H fluorination of heteroarenes is a straightforward approach to accessing valuable heteroaryl fluorides but remains a formidable challenge. Herein, we report a general strategy for visible-light-induced C-H fluorination of heteroarenes via the merger of N-F fluorinating reagents and silane. Electron paramagnetic resonance experiments provide evidence for the homolytic cleavage of the N-F bond under blue light-emitting diode irradiation, which is the key step in the process. This transformation is metal-free, photocatalysts-free, and site-selective under mild reaction conditions (ambient temperature, visible-light irradiation, tolerant to H2O). The robustness of this protocol has also been highlighted by late-stage modification of complex and medicinally relevant molecules.