Palladium-Catalyzed Regioselective C4-H Acyloxylation of Indoles with Carboxylic Acids via a Transient Directing Groups Strategy

The development of an efficient method for the synthesis of C4 oxy-substituted indoles is an appealing yet challenging task. Herein, we report a general palladium-catalyzed TDG approach for the direct C4-H acyloxylation of indoles. The protocol features atom and step economy, excellent regioselectivity, and good tolerance of functional groups. Moreover, the reaction can accommodate a range of carboxylic acids including benzoic acids, phenylacetic acids, and aliphatic acids.