Halogen-Bonding-Promoted C-H Malonylation of Indoles under Visible-Light Irradiation.

Herein, we report a halogen-bonding-based electron donor-acceptor (EDA) complex-promoted photoreaction for the synthesis of C2-malonylated indoles. The protocol provides access to a broad range of functionalized indoles in good yields through the coupling reaction of indoles with diethyl bromomalonate under visible-light irradiation without the need for any transition-metal catalyst or photocatalyst.