Visible-Light-Mediated, LMCT-Enabled C(sp3)-H Bond Alkylation of Alkanes and Silanes via C-4 Functionalization of Coumarins

A visible-light-promoted FeCl3-catalyzed protocol for the generation of alkyl and silyl radicals from alkanes and silanes, respectively, is described. Employing a chlorine radical as a hydrogen atom transfer agent, alkyl, and silyl radicals were accessed and functionalized by addition to coumarins, ultimately resulting in a redox-neutral alkylation/silylation. The reaction occurs without an exogenous oxidant and under mild conditions, highlighting the potential of 3D-metal compounds in achieving challenging bond activations via photochemical excitation.