Visible-Light-Promoted Indole C-3 Formylation Using Eosin Y as a Photoredox Catalyst

Abstract A visible-light-mediated C-3 formylation of indole catalyzed by eosin Y has been developed using tetramethylethylenediamine as a carbon source and air as an oxidant. This protocol shows high tolerance to a large quantity of functional groups under mild conditions and provides 3-formylated indoles with good yields. This method is a highly attractive alternative to the approach of traditional formylation.