C2-Benzylic C(sp3)-H Alkylation of Indoles Enabled by Photoinduced, EDA-Complex-Mediated Radical-Radical Cross-Coupling

Abstract

2-Alkylindoles are privileged motifs that serve as versatile intermediates and building blocks in synthetic and medicinal chemistry. Herein, we report a photoinduced, EDA-complex-enabled C2-benzylic C(sp³)-H alkylation of indoles with bromides through radical cross-coupling. This developed protocol provides facile access to 2-alkylindoles from structurally varied 2-methylindoles and bromides under mild reaction conditions with simple operation. Mechanistically, the well-designed EDA complex by rationally leveraging π-electron-rich indole and electron-deficient halide and electronically matched radical cross-coupling is crucial to the success of this new open-shell methodology in the functionalization of indoles.