Visible-Light-Induced Photocatalyst-Free C-3 Functionalization of Indoles with Diethyl Bromomalonate
A visible-light induced green and efficient method is developed for the synthesis of α-indolyl diethyl malonates. The reaction proceeds without any photocatalysts or ligands in green solvent in short time. Moreover, the reaction mechanism has been clearly studied by control experiments, spectrophotometric studies and density functional theory (DFT) calculations. The results showed that the photocatalyst-free transformation may proceed via an XB-promoted radical process. The EDA complex formation of diethyl bromomalonate with base is the main reason for the reaction initiation.